What Should I Do?

Solar Panels ready for mounting.

Installing a Solar Energy System

Building resiliency with the sun
Saturday, November 27, 2010, 12:51 AM

Like many of you reading this article, I am fairly new to the realization that our future may not turn out the way we originally planned.  A little over two years ago, after the financial turmoil set in, I began to wake up from my comfortable, relatively uncomplicated life and take a closer look at what was going on around me. 

I was first introduced to the Crash Course by an attendee at the 2009 CPAC Liberty Forum in Washington, DC where I had gone to hear Ron Paul speak.  Little did I know how dramatic an impact that one conversation would have on my life.  After watching the Crash Course a couple of times, many pieces of the puzzle started to fall together, and I quickly progressed to Stage 4 - Fear.  (See The Six Stages of Awareness for more on that topic).  A few weeks after I attended Dr. Martenson's Lowesville seminar, I decided it was time to take immediate action.  I've also had to deal with the challenges of convincing my partner that these changes were really worthwhile and necessary and that I wasn't a raving lunatic who would soon be wearing a tin foil hat!

I hope reading about the thermal and photovoltaic solar systems we have installed will encourage you to think about actions you can take to prepare for our uncertain future.  Since it would be impossible to even begin to give every detail about how the systems work or how to put one together, my goal is to show what can be done, give you things to consider, suggest rough costs, and provide links for further research.

Our House – NOT a Model of Sustainability

I think it is important for you to know the environment and initial problem in order to make sense of some of the design/implementation decisions we have made.  We moved into our house in Albuquerque, NM during the housing bubble (before I took the “red pill”, so it seemed like a good idea at the time).  After the housing bubble burst, it would have been difficult to sell our house, so moving/downsizing was not really an option.  I suspect many people are in the same situation – after all, not everyone can sell their McMansions

The house is large, with tall ceilings and many large, mostly east/north facing windows.  I'm pretty sure the slab is not insulated, or at least not insulated well, and I question the insulation quantity and quality in the walls - basically it's a heating and cooling nightmare (my view, not the utility companies'). 

The house is heated with hydronic radiant floor heat, and before the solar installation/upgrade, it used a 13-year-old, probably 75% efficient, 280,000 BTU natural gas boiler and a separate 150,000 BTU 100 gallon domestic hot water heater.  Our gas usage ran about 2 Therms/day during the summer (domestic hot water, cooking, clothes dryer) and 14 Therms/day in the winter.  Yes, this caused us major heart attacks with each winter utility bill. 

Cooling is provided by three large evaporative coolers (very energy-efficient, compared to refrigerated air).  We also have a roughly 600+' well as our water supply, which contributes considerably to our electric usage (generates about 165 gallons per kWh).  Our electric bill averages about 45 kWh/day in winter (lighting, water, electronics) and 65kWh/day in summer (cooling, increased water usage).

While the systems we installed are large by most residential standards, all of the components described are scalable to any size home and should be fairly scalable pricewise as well.

The Panic

After performing the Crash Course Self-Assessment, I realized how precarious our situation was in regards to energy availability and energy prices.  I was also very concerned that a SHTF event could occur at any time, so I placed a high value of getting to a “self reliant” -- not necessarily long-term sustainable -- posture as quickly as possible.  Fortunately, we live in New Mexico, with a fairly mild climate and lots of sunshine.  I began with the standard Internet research and called some of the local solar vendors.  Everyone said that the first step is to take the time to begin by reducing your usage.

For electricity, this primarily means replacing incandescent lights with CFL's and replacing old appliances.  Unfortunately, our house is almost entirely lit by halogen recessed lighting cans, and nearly all of them are on dimmer switches, which are not compatible with CFL's.  LED lights may be an option in the near future, but they are just now becoming a reasonable option (light quality/quantity, dimmable, price).

For heating, this means replacing older inefficient heating systems (boiler) and insulating.  Again, this was a significant problem with our house.  Because of the large uninsulated slab and large window area, any inexpensive improvements beyond basic weatherproofing will not significantly lower our heating requirements.  We also have a flat roof, which means no attic to insulate.  On top of that, our interior walls are all plaster, so adding insulation to the walls is a very expensive option.

This all lead to one conclusion – if you live in a relatively modern home (less than 30 years old), it is unlikely that you will be able to significantly reduce your usage easily.  It may be that the incremental cost of a larger solar installation will be less expensive than usage-reduction improvements you can make.  If this is the case, and if you have the financial resources available, you are probably better off building a system larger than you need and working on reducing usage later.  Any excess capacity (particularly electricity) will most likely be a useful thing to have in the future (electric car, excess to sell, etc).

Goals

I believe that we are highly unlikely to have a crisis where there would be a complete breakdown of society and we would become agrarian overnight (the Mad Max scenario).  But I do suspect that we will have dramatically rising prices and brief (week long?) disruptions to electricity and other energy supplies in the US.  The US still has a fair amount of oil and other resources, and when it becomes generally apparent that the current situation is unsustainable, prices will rise, forcing a reassessment of what is important (food, shelter) over what is luxury.  I believe, as Chris Martenson does, that we will suffer successive shocks and then adjust to a new lower normal as a society.

With this assessment, I don't believe it is necessary to build a 100% off-grid-type house, which can get very expensive.  Here in New Mexico, we have mostly sunny weather, but on occasion we can have 3-4 days with heavy overcast skies.  Building a system to handle those situations would require massive storage tanks for heating and huge battery systems or alternative generation system (along with a fuel source).  Instead, we took the approach that would support producing most of our energy in “good” conditions relying on the grid for those non-sunny days, and in rare cases producing minimal required amounts for the times when solar and grid are not available.

Thermal Solar System

Thermal solar systems use collectors to capture and use heat directly from the sun, as opposed to photovoltaic systems (PV), which convert sunlight into electricity.  There are many types of thermal solar systems, both passive (no mechanical components– built into design of building) and active.  Some use the heat immediately, such as with inexpensive solar-air based collectors, while others store the heat for later use.

Our System – Design & Theory of Operation

Our thermal solar system is a closed-loop, pressurized, hydronic solar-assisted heating system (that's a mouthful), which provides space heating and domestic hot water.  It is “assisted” in that during cold winter months and on cloudy days a natural gas boiler is used as backup.  The system is designed to reduce our space heating and domestic hot water natural gas usage by around 60%.

 

A closed-loop, pressurized system uses a heating fluid, in our case glycol, which is circulated through the solar collectors and to a heat exchanger.  The glycol is always present in the collectors, as opposed to open systems, which use a “drain back” system, where at night the solution is gravity-drained from the collectors to prevent freezing.  A solar PV panel is used to run DC pumps, which keep fluid circulating in the collectors whenever sunlight is hitting them, which helps to prevent overheating from stagnant fluid in the collectors.  Glycol is only used in the collector loop; the rest of the system uses water.  When heat is available at the heat exchanger and needed by the system, the pump is turned on, circulating water from the cold side of the manifold through the solar heat exchanger and the warmed water back to the manifold.

In the center of the diagram is a Caleffi Manifold that accepts hot water inputs from the boiler and solar collector heat exchanger, and then distributes heat as needed to the tank heat exchanger for domestic hot water or out to the floors for radiant heating.  The manifold allows the pumps to operate independently of each other at different rates and pressures.  When heat is called for, to either heat the tank for domestic hot water or the radiant floor heating system, the appropriate pump is turned on.  If the water in the manifold is not hot enough, the boiler can be turned on and the pump enabled to raise the temperature in the manifold. 

Our system only uses the storage tank for domestic hot water; it is not used as a storage medium for household heating.  We can do this because we have radiant floor heat and can use the concrete mass of the house as our storage medium.  During the day, when solar heat is available, it is pumped into the slab, then at night the slab radiates the heat into the house.  Since heat is added during the day, it means late afternoon and early evening are when the heat is mostly radiated out into the house.  The system uses multi-stage thermostats, which allow it to heat the house more with solar energy (free) than it does with natural gas, and it allows us to determine our “trade off” tolerance between “cheap” and “stable heat.”

In a system without radiant floors, storage tanks similar to the domestic hot water tank (only larger) could be used to hold heated fluid, which could then be circulated back to the manifold when needed for use in other heating systems (radiant, forced air, etc).  It is also possible to add storage tanks to a system such as ours for storage of excess heat to be used on cloudy days (a potential off-grid solution).

The Heating System Conversion – Installation of Solar-Assisted Heating

Conceptually, the conversion was very simple.  Remove the existing boiler and conventional water heater and install a new high efficiency boiler, a hot water storage tank, manifold, and pumps, and the solar collectors on the roof.

The first major component was the replacement of the old natural gas boiler with a new high-efficiency boiler.    A Triangle Tube Prestige Solo 250 (250,000 BTU/hr) boiler was installed.  Compared to the old boiler, it is a marvel of technology.  It can modulate the burner based on input water temperature, outside air temperature, and use (Domestic Hot Water or Floor Heating), versus the old boiler, which was either on or off.  It is also about ¼ the size of the old boiler.  Just changing the boiler probably provided a 15-20% reduction in gas usage.

Next, the old traditional 100 gallon water heater was removed and replaced with a Triangle Tube Smart Series Indirect Fired 120 gallon Water Heater.  It is a large, heavily-insulated stainless-steel storage tank with an integrated heat exchanger.  A hot water source (the newly installed boiler or solar) is used to heat the domestic hot water supply via the heat exchanger so that the heating fluid and the domestic hot water never mix.  I suspect just making the change from the traditional water heater to this setup using the new boiler also made a considerable improvement in our energy usage.

Below is a picture of the utility closet after the system was installed.  You can see the boiler on left with the yellow energy usage sticker.  On the right is the 120 gallon storage tank, and in the center is the distribution manifold.  The rest of the plumbing consists of mixing valves, pressure relief tanks, and zone valves; out of the picture is the heat exchanger used to collect the heat from the solar panels for the manifold.



 

One of the things that surprised me was the small size of the heat exchanger for the solar collectors.  For some reason I was expecting a large device, but here is a picture of ours with a ruler next to it.

There are 13 SS-40 4'x10' flat plate collectors from Solar Skies mounted on our roof, some which can be seen in this picture along with two small PV panels that power the DC circulation pumps. 

The panels work by circulating a glycol solution slowly through small copper pipes with fins attached to them that transfer the heat collected to the solution.  The panels are placed at a very steep angle (75 degrees) so that they collect a lot of heat in the winter months, but much less in the summer months since it is not needed then.  Excess heat would have to be dissipated once the domestic hot water tank reaches its maximum temperature (190 degrees).  If this occurs, the system will dump heat into the slab as needed (clearly not desirable in the summer).  This is generally not much of an issue if the system is appropriately sized.  Of course, if you happen to have a pool, this is much less of an issue since a pool/spa can be used as a heat sink.

Control System

We are currently beta testers for a new device called a SLIC from Solar Logic.  It is a computer-based control system for a solar-assisted heating system.  It replaces the relay and traditional thermostat controls normally used with an entirely software-controlled system.  It allows for much finer-grained control over the system, as well as much better monitoring of its performance.  Some of the features include:

Dashboard – viewing room temperatures, thermostat settings, valve/pump status from your computer

Data Logging – logging of settings and actions for performance analysis

Operational Changes – monitoring water fluid temperature changes, when the boiler is used versus solar, etc.

Another unique feature of the system is the ability to reverse the flow of the system at night in the summer to pull heat from the slab (floors) and radiate it through the collectors as auxiliary cooling.  I'm pretty sure this only works in climates with low humidity where there is a substantial temperature differential from day to night.

Performance

The designers of our system say a good rule of thumb is that each 4'x10' collector is approximately equal to ½ gal of propane per sunny day here in Albuquerque.  That means with 76% sunny days, we should have about 4.5 Therms/day on average reduction in our natural gas usage:

76% * ½ g. propane * .92 T / g. propane * 13 collectors = 4.5 Therms

From an actual gas usage perspective, at our current usage we will need about 125 Therms of natural gas in the month of November, which is considerably lower than the last several years, in which our November average was 303 Therms.  This represents about a 60% reduction, which is slightly better than the anticipated collector output calculated above.  However, all of this is extremely difficult to measure mathematically, since our heating needs can be highly variable depending on the weather.  I suspect we will need several full years of data to be able to accurately assess the system.

From a subjective view, the system seems to be performing well.  I can watch the dashboard on my computer during the day and see that from about 9am until 4pm, the system is generating 150+ degree water and it is being put into the floors and domestic hot water tank.  I generally see the room temperatures begin around 65 degrees in the morning and heat to about 72 before the solar cuts off.  Then the rooms seem to coast until about 1am, when they begin to cool.  This matches up well with the times when most of the rooms are actually occupied.

Because we can specify which rooms to heat with boiler and which rooms to only use solar, I think we are keeping the house considerably warmer overall than we have in past years.  I'm happy with the system and the peace of mind it gives knowing that we have some heat even if natural gas becomes unavailable or prohibitively expensive.  It allows me to sleep much better at night.

Cost, Incentives, and ROI

Okay, so now we get to the nuts and bolts.  We paid to have the system professionally designed and installed.  The total pretax credit price was $62K.  $55K of that was solar, and the rest for the boiler.  In New Mexico, there is currently no gross receipts tax (sales tax) on solar installations (parts and labor).  So that price included about $3300 worth of savings on $55K of the system. 

Incentives and tax credits reduce this amount considerably:

FederalResidential Energy Efficiency Tax Credit – 30% on boiler, $1500 limit: -$1,500

FederalResidential Renewable Energy Tax Credit – 30% on solar, no limit = -$16,500

New Mexico - Solar Market Development Tax Credit - 10% on solar, $9000 limit = -$5500

All the credits bring the final price down to $38,500.  

When I first begin analyzing our usage in 2008, natural gas prices were averaging $1.28/T.  There has been a large drop in price over the last couple years, reaching a low of $0.37/T in summer of 2009.  The price has been gradually rising, with the current price in November 2010 being $0.53/T.  It would be difficult to cost-justify the system if natural gas prices remain low.  However, at the $1.28/T price the ROI works out to be about 3.5% over an assumed 20-year life of the system.  

If you are a DIY type and have the skills and time to do so, you can save some on the labor costs, which were roughly 30% on our project.  Here is the approximate pre-tax credit cost breakdown for the high cost materials:

Photovoltaic (PV - Electricity)

Photovoltaic systems convert sunlight directly into DC (direct current) electricity.  That DC power can then be converted to AC (alternating current) using a device called an inverter.  AC current is the form of power you receive from your electric utility company via the electrical grid.

Photovoltaic systems come in three primary flavors:

  • Grid-tied – This is the primary type of installations you see going up in neighborhoods around the country and now makes up about 70% of the solar PV market. Grid tied systems will reduce your energy costs but do not provide resilience against power outages. In a grid tied system if the power grid goes down, then the PV arrays becomes an art sculpture.
  • Off-grid – Generally deployed by people living in places where conventional grid power is not available or it would be extremely expensive to run power lines.   Off grid systems have batteries and often alternative generation capabilities (such as propane generators). Off grid systems can be extremely expensive depending on required power reliability.
  • Grid-tied w/battery backup – In this type of system, the grid is assumed to be available most of the time with batteries and potentially alternative generation capability built into the system to add resilience against grid failure.   This capability can add significant cost depending on the duration and power required during off grid operation.  

Systems with batteries (grid tied, grid tied w/battery backup) come in two flavors:

  • DC-coupled – This is the most common and traditional method for attaching batteries to a PV system.  In a DC-coupled system the batteries are generally charged with the DC current generated by the PV array with the use of charging controllers.  Power from the batteries is then used by an inverter to generate AC current for household use.  Most off-grid solutions are DC-coupled.
  • AC-coupled – In an AC-coupled system, the PV arrays are connected directly to an inverter, which generates AC power (same as a grid-tied system) and batteries are attached to a separate inverter/charger, which can take AC power and charge the batteries or pull power from the batteries to generate AC power when the grid and/or PV inverters are not supplying enough power.  One advantage to an AC-coupled battery solution is it can be retrofitted onto many existing grid-tied systems. 

DC-coupled systems are designed to maximize the efficiency of battery charging, while AC-coupled systems are designed to maximize AC power delivered.  If you are likely to use the batteries on a regular basis and will power a significant amount of your load without the grid available, then a DC-coupled system will likely be the best solution.  If, however, you are expecting the grid to be available most of the time, then an AC-coupled solution may be best.  Here is a blog article that discusses the tradeoffs between AC and DC coupled systems.

Any grid-tied system (any consumer generation capability – not just solar) is required to disconnect from the grid (intentional islanding) or shut down (anti-islanding protection) if the grid goes down.  First, this is a safety issue, as the utility workers do not want small generation systems energizing the lines while they are trying to make repairs.  Second, it's a load issue.  A small consumer generation system is not going to be generating enough power to run all of the neighbors' equipment.  This will cause an unmanageable load to the customer generation equipment, possibly causing damage.  Before authorizing start-up of a PV system (customer generation facility), the utility company will test that the islanding protection performs as expected.

In the US, all grid-tied systems have the ability to be net metered (required by law).  Net metering permits the consumer to feed power back to the electrical grid, offsetting their consumption.  In a grid-tied PV system, the consumer typically generates more power than they use during the day and the meter spins backwards, then at night when the PV system is not generating power, the meter spins forward.  At the end of the billing cycle, the consumer will pay for the “net” energy they consumed.  If they generated more than they consumed, the utility will either credit them for future use, or pay them for the excess they contributed to the grid (generally at a lower-than-retail rate).

New Technology – Micro-Inverters

In traditional PV systems, multiple panels are connected together serially into a string, which is then connected to the inverter. The number and type of panels must be properly configured for the inverter to produce optimum power, and this requires a fair amount of expertise.  One down side of the string configuration is that the string only performs as well as the worst panel.  If a panel is shaded (even a minor amount), its performance can drop substantially, affecting the whole string.

There is a relatively new technology in the field of PV called a micro-inverter.  Instead of connecting multiple panels in string to a central inverter, each panel is connected to its own inverter (generally attached to the back of the panel).  There are some significant advantages to using micro-inverters, and a few downsides:

Advantages:

  • Minimal expertise required compared to traditional string/inverter configurations.  Much easier for the DIY market.
  • Output from one panel not impacted by performance of other panels.  In installations where shading is possible during part of the day, the performance of the system as a whole will not be impacted nearly as much as in a traditional inverter configuration.
  • Ability to grow a system one panel at a time.  In the central inverter, generally 7-15 panels must be connected to a string, thus requiring growth in larger increments.
  • Since each panel has its own inverter, it removes the single point of failure with a central inverter.

Disadvantages:

  • Cannot be used in DC-coupled systems, since DC power from the panel is immediately converted to AC.  This limits their use in off-grid systems.
  • Generally more expensive than a central inverter for medium to large systems.
  • Since each panel has its own inverter, there are many more parts that can potentially fail.
  • Unproven long-term reliability.
  • Current systems on the market require a subscription service for monitoring.

If you would like to know more about micro-inverters, Enphase Energy and Enecsys are two manufacturers of micro-inverters.

Racking – Roof Mount, Ground Mount, Pole Mount, Trackers – Oh My!

There are many choices when it comes to mounting solar panels.  Generally a roof or ground mount solution will be the least expensive.  If you have the space and few obstacles on your roof that would shade the panels, that is probably the preferred mounting method.  They are out of the way and less prone to shading and vandalism or theft.  Ground mounts are often easiest for the DIY market since they do not require potential roof-damaging penetrations, work on a ladder, etc.  Most ground and roof mounts are fixed at a set angle and require little maintenance other than an occasional cleaning once installed.

Pole mounts can be used where ground mounts are not desired due to potential shading considerations.  They tend to be more expensive because they can require large amounts of concrete to keep the giant solar array from blowing away in strong wind.  They are often set at a fixed angle, but many can have the angle adjusted multiple times during a year to gain better performance.

PV panels perform best when perfectly perpendicular to the sun's rays. As the sun's position changes daily and seasonally, a fixed PV array's performance will change.  For optimum performance, a fixed array will be faced due south (north hemisphere) and at an angle equal to the latitude of the location.  If an array has an adjustable angle, this site has instructions for calculating the proper angle at different times of the year.

Trackers allow an array to follow the sun on either one or two axis.  A single-axis tracker will have the vertical angle fixed and track the along an east-west path.  Most will allow the angle to be adjusted seasonally for better performance.  A two-axis tracker attempts to keep the array perpendicular at all times to the sun, tracking it both daily and seasonally.  Trackers can be passive (fluid based) or active (electronics/motors).  A two-axis tracker can improve performance by up to 40%, but it comes with added cost for the tracker and maintenance, since it is adding mechanical and potentially electrical components to the system.

Selecting a Vendor and Determining Your Needs

There are many new vendors peddling PV systems.  It has been a sort of gold rush over the last couple of years, as many of the contractors, electricians, plumbers, and other construction-type vendors rushed into solar after the housing collapse.  Due to the incentives provided by states and utilities, it is one of the bright spots of spending.  Because of this, it is important to have a basic understanding of PV systems before you decide to purchase.

Before you contact any vendor, you need to know how much power you use on average.  Many utilities can provide your last year's usage online.  In fact, one the first things many PV vendors will do is get your utility information (account #, address, etc.) so that they can pull your usage records for you when preparing their quotes.  Most will provide you with quotes showing you how much you will generate and how much you will save by installing their systems.  As with any large purchase, get multiple quotes. 

If you plan on having battery backup, you will need to analyze your loads to determine how much battery capacity you will need.  You will also want to determine how long and what loads you wish to keep up during a grid failure.  To do this, you can use small plug-in meters that are available from many locations on the Internet or from your local Radio Shack.  I use the P3 Kill-A-Watt meter; it's about $25 and you simply plug it into the wall and then plug in the device you want to measure. You can leave the device plugged in, and then check the total usage and divide it by the time to get an average.  You may want to do this just to have a better understanding of how much power a device uses. 

If you have larger loads that you would like to measure that are inconvenient or too large for the Kill-A-Watt meter, such as a well pump, you can simply turn off all loads except the one you wish to measure, and then use your electric meter to determine the power being drawn.  Instructions for doing so can be found here.

When you first start getting quotes for photovoltaic systems from vendors and are currently a grid-tied customer you will find they will all try to discourage you from considering any kind of battery backup.  Most will point out the incredible reliability of the grid.  They will encourage you to investigate alternative backup solutions (such as propane generators) if you really want backup power.  This is because batteries are very expensive, more complicated than other backup solutions, and generally require more maintenance.  Also, many of the PV people are relatively new to the business and have little or no experience with a battery-based system.  If you decide you want a battery backup system, it is helpful to find a vendor that has off-grid experience or a vendor that has worked with AC battery backup solutions, such as those for data centers.

Our System

The short description:  Our system is 10.8 kW with AC-coupled battery backup.  It consists of 48 SunPower E18 225W black panels mounted on 3 poles with DPW Power-Fab top of pole racks.  Each pole has a SunPower 4000m grid tied Inverter (a re-branded SMA Sunny Boy 4000-US) connected to 16 panels arranged as 2 strings of 8.  For the battery backup, we have 2 SMA Sunny Island 5048-US off-grid inverters connected to a 480Ah@48V C&D Technologies msEndur II battery stack.

So what does all that mean?  Why did we go with that equipment?

I'll start with the grid-tied portion of the system.  Since we covered the roof with thermal solar collectors, a roof mount was not an option.  Due to the position of our house on the lot, it left only a small area that would have a reasonably unshaded south facing exposure.  Our neighbor's house behind us has a fair number of trees, so we needed to use pole mounts to get the array above potential shade from their trees.  Placing the panels high also reduces the potential for vandalism or theft.

The first decision was the rough size of the array, which was driven by our usage and the potential for an electric vehicle in the future.  Also impacting our decision was the favorable higher REC credit incentive rate (see below) for an array greater than 10kW offered by our local utility.

We chose DPW racks because they were reasonably priced, made locally, and had the ability to adjust the angle of the array.  This decision impacted the choice of panels.  SunPower panels have a higher efficiency, which means less surface area is needed for a given power generation.  In most instances, this may not be much of a factor in the choice of panels.  In our case, it meant we could reach our desired array size with only 3 poles, versus 4 poles with other panels we considered.  The racks have a maximum surface area due to wind loading, and with SunPower we could fit 16 panels per pole, versus only 12 or 14 of other brands.  It should be noted that SunPower panels have a large price premium, but the cost difference was less than the cost of adding an additional pole and had an added aesthetic value of less poles.

We chose the SunPower (SMA Sunny Boy inverters) because they are designed to work with the SMA Sunny Island off-grid inverters.  This allows us to use the SMA Sunny WebBox monitoring appliance.  In addition, the Sunny Boys are designed to work with the Sunny Islands when the grid is down, by allowing the Sunny Islands to throttle power production from the Sunny Boys.

The poles are 16' long 12” round 1/2” thick schedule 40 steel pipes.  They each weigh just under 900 lbs.  They were placed in 4' x 4' x 6' deep holes, which were then filled with re-bar reinforced concrete.  This is the required mounting to withstand up to 90 mph winds.  Here is a picture of the poles being installed:

Next, the racks were placed on the poles:

Then the panels were installed, an inverter attached to each pole, and the panels connected to the inverters.  This would be a complete standard grid-tied installation and can function as such:

The inverters are connected to a meter that is used for measuring generated power for use in calculating the REC credit incentive.  That meter then ties into our critical loads panel.

Next was the installation of the battery bank and the off-grid Sunny Island inverters.  The inverters work as a master-slave configuration providing 240V power, which can be used to power our well.  The batteries are sealed VRLA AGM (valve regulated lead acid absorbed glass mat) batteries:

We choose the C&D Technologies msEndur II batteries because they have a long life (20 years), low maintenance requirements, and are designed to be used in applications where they primarily sit at float rather than being cycled every day like batteries used in off-grid applications.  When working with a vendor, make sure they understand how the batteries will be used.  How the batteries are discharged (frequency and depth) can have a huge impact on the choice of batteries.  Keep in mind that choosing a cheaper battery can result in higher costs later due to having to replace the batteries more often.  This is particularly important as most of us here believe that resources will become scarcer and more costly in the future.

The installation of the Sunny Island inverters required reworking our existing breaker panels to place “critical loads” into a separate panel.  The Critical Loads panel contains loads that will be powered by battery and/or PV when the grid is down.  It includes our well, heating system pumps and controls, refrigerator, freezer, and a few lights and plugs.

Below is a simplified drawing showing the interconnection of the components.  The “cut-off switch” is built into the Sunny Island inverters.  Not shown is the Sunny WebBox, which is used to monitor the system.  It connects to each of the Inverters via an RS-485 network and to our home network.

Operation

Under normal operation, the SunPower (Sunny Boy) inverters start up each day when the PV panels begin producing power.  The power produced spins the REC meter and then is fed into our primary panel. The power is either used by loads in our house or sent out to the grid through our primary electric meter.  If we are using more power than we are generating, the meter spins forward.  If we are using less, then it spins backwards (net metering).  The Sunny Island battery backup inverters allow power to pass through to the critical loads panel and draw any needed current to charge the batteries.  This is the typical operation 99.9+% of the time.

If grid power is lost, the SunPower inverters immediately shut down (anti-islanding protection) and the Sunny Island inverters begin generating power to the critical loads panel from the batteries.  At the same time, the Sunny Islands isolate the critical load panel and the SunPower inverters from the grid, forming an intentional island separate from the grid (sometimes called a mini-grid).  The SunPower inverters will then see power just as they would if the grid were available.  After a few minutes with power visible, the SunPower inverters start up and begin producing power if solar is available.  Any power generated will be fed to the critical load panel, and excess power will be used to charge the batteries.  If the batteries become fully charged and the critical loads are not consuming all the power generated, the Sunny Islands can adjust the frequency of the power they are generating to throttle the SunPower inverters to meet the current demand.

When grid power becomes available, the Sunny Islands will connect the critical load panel and the SunPower inverters back to the grid.  During the switch, the SunPower inverters will shut down until grid power is visible for several minutes and then start back up into normal operation.

Cost, Tax Incentives, REC Credits and ROI

We paid to have the system professionally designed and installed. The total pretax credit price was $98K. As with the thermal solar in NM there is currently no gross receipts tax (sales tax) on solar installations (parts and labor). So that price included about $6,600 worth of savings.

Many of the same incentives from the thermal solar applied to the PV as well:

FederalResidential Renewable Energy Tax Credit – 30%, no limit = -$29,400

NM - Solar Market Development Tax Credit - 10%, $9000 limit = -$9,000

All the credits brought the final price down to $59,600.  

The approximate pre-tax credit breakdown of the major components is shown below:

As you can see the battery backup added considerably to the price, particularly with the type of batteries we chose. There was also a significant increase in cost for the pole mount racks versus a roof mount system.

While the tax credits are good, the big incentives are with the utility company REC credits and energy savings. Our utility company offered (recently changed) two programs for interconnection. One was a small PV program (< 10 kW) which is net metered and pays $0.13/kWh REC credit for all power generated and any excess is carried as an energy credit that can be used in the future. The other was a large PV program (> 10kW) which is also net metered and pays $0.15/kWh REC credit for all power generated and consumed and any excess energy is paid for at their “loss avoidance rate”. We are billed under the large program, so for example, if we used 1900 kWh and generated 2000 kWh in a month this would be the outcome:

In this example, we save $190 that we would have paid to the utility company, and on top of that the company sends us a $290 check for a total net gain in one month of $480.00.  The REC credits are taxable as income so that will reduce the payout some, but I have calculated on our system that after all taxes we should be getting a average net gain of about $307/month.  Over a 20 year life of the system, I have calculated the ROI to be around 2.1%.  Without the battery backup, the system would have an ROI of around 6%, and with roof mount instead of poles it would easily push the ROI to 10%.  So even with the batteries, the ROI is better than the current rate on a CD at a bank, and the savings and sale back portion are inflation adjusted!

In the future as energy prices rise, I suspect the savings and sale-back prices to rise substantially, making the non-inflation-adjusted REC credit become less important.  Incentives vary widely by country and state; some are considerably better than those in New Mexico so you'll have to do some research and spend a lot of time with a spreadsheet.

Performance

Unlike the solar thermal system, which is difficult to measure, the PV system gives instant feedback on how it is performing.  The Sunny WebBox logs data from all inverters every 5 minutes, and with a 2 GB SD card inserted, it can keep the logs for more than a year.  The logs are updated several times during the day to the SMA Sunny Portal website, where I can check on the performance of the system at any time from anywhere in the world.  You can see our current and historical performance here.

The system has so far performed better than modeling suggested.

Conclusions

Hopefully you now have a little better understanding of thermal and PV solar installations and perhaps some encouragement to investigate them if you haven't done so already.  While expensive, with current incentives and energy prices it is financially justifiable to install these systems versus other investments, and you will end up with a hard tangible asset versus a piece of paper.

I would also suggest that if you plan on installing any of these types of systems, you begin doing so soon.  It took almost a year from starting research to having our systems installed.  After picking a vendor and signing contracts, it took almost 6 months for the systems to be up and running. 

In addition, I firmly suspect we will see a drop in subsidies, particularly from the states and utilities, as the economy worsens.  While it's nice to think of these subsidies as being the right thing to do, they are absolutely unsustainable.  It is a transfer of wealth to those who act from those who don't.  Take action!

From a mental perspective, it is a great relief knowing that we can now survive fairly severe collapse with little or no natural gas or electricity and still keep warm, have lights, and run water.  If you are having trouble sleeping at night due to worry about what's coming, having systems such as these is the best sleeping pill you can find.

Resources

There are many great resources available for free or cheap on the Web.  I do not have any financial relationship to the sites listed below; I'm just a happy user of their services. 

DSIRE - Database of State Incentives for Renewables & Efficiency – This website has listings of both federal and state incentives available.  Check out the incentives soon, as some covered here expire at the end of 2010.

NREL – National Renewable Energy Laboratory – This is an invaluable site.  It provides renewable resource maps for most renewable resources.  PV Watts is a free Web application on the site that lets you enter information about a system and it will calculate your estimated production by month.  Of all the tools, I used this one the most during my planning. 

SRCC – Solar Rating and Certification Corporation – Look up the performance characteristics of solar collectors and PV modules.  Make sure the components used are certified, as that is required for many of the incentive programs. 

Home Power Magazine – I highly recommend subscribing to the online version of this magazine as a first research step.  For $15 you get a year of access (6 issues) and can look at the past 18 issues as well.  There are a lot of great articles on solar, wind, and other renewable sources for the residential market. 

Suppliers for our systems:

CST Solar - The company that designed and installed our PV system.  If you are in the Albuquerque area and use them, please let them know I sent you!

Sun Power – The company that makes the PV panels we used.

SMA – Manufacturer of the inverters, including the Sun Power labeled inverters we used.

DPW Solar – Manufacturer of Power Fab PV mounting racks which we used.  Also in Albuquerque.

Solar Logic, LLC – Manufacturer of the SLIC controller for our Thermal Solar System.

Other notable vendors:

AAA Solar - A thermal solar supplier located here in Albuquerque.  They have a free downloadable catalog that has supplies, prices, kits, and plans for thermal solar aimed at the DIY market. The catalog is a great resource just to see what is available and get ideas on costs for such systems.

Affordable Solar – Another supplier located here in Albuquerque, which is also aimed at the DIY PV market. They are a great resource to check out prices on modules, inverters, and racking systems. They also have complete kits available.

altE store – This store has a lot of free (registration required) educational resources in their altE university.

Zomeworks – Another Albuquerque company that makes passive solar trackers.

Wattsun – An Albuquerque company that makes active solar trackers.

Our solar inspection team, which kept an eye on things during the construction.

Related content

34 Comments

Poet's picture
Poet
Status: Diamond Member (Offline)
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Posts: 1836
Re: Installing a Solar Energy System

Thank you for sharing your experience and setup. You really got a sweet system going. I am totally envious! Selling power to the energy company!!

For me, with a budget in the hundred dollar range (and being an apartment renter), I would say my order of priority would be:

1. First get efficient: conserve, insulate and weatherize if it makes sense. (It's unlikely I'd get into glazing as I am a renter, but some window film or coverings might be a good idea.)

2. Get a solar battery recharge capability to trickle-charge good AAA, AA, 9v, C, D, etc. batteries that can take thousands of charges. A simple system with batteries would cost well under $100 and the panel could just be taped to a sunny window or placed on a windowsill. The batteries can run radios, flashlights, perhaps cell phones (with certain chargers), etc. It just makes a whole lot of sense because this is portable and affordable. (http://www.peakprosperity.com/blog/what-should-i-do-basics-resilience-pa...)

3. If I became a homeowner (mortgage-holder?) then I'd start considering the cheap(er) solar alternatives - solar attic fan, solar hot water, a DIY Trombe/Morse wall (http://www.builditsolar.com/Projects/SpaceHeating/SolarWall/SolarWall.htm capable of providing 90 degree heat on a sunny winter day) , etc.

4. Then with money, an actual solar energy system to help power the yellow perch/tilapia aquaponics system in my greenhouse. :)

Poet

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lexscripta
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Re: Installing a Solar Energy System

All of this is fantastic, where the average sun is around 300 days per year, as in New Mexico - but what about people who live in shaded areas, or in places like Illinois, or WIsconsin? Clearly such solutions as the article suggestes probably wouldn't mean much without the benefits of a suitable geographic location.

Damnthematrix's picture
Damnthematrix
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Re: Installing a Solar Energy System

"It may be that the incremental cost of a larger solar installation will be less expensive than usage reduction improvements you can make"

In my experience......  NEVER.

I sell PV systems for a living now.  Recently, a friend contacted me wanting to upgrade her 1 kW system to 2 kW. It was going to cost her ~ $6000.

While I was there, I noticed her fridge (which turned out to be 24 yrs old..!) ran non stop.  So I put an energy meter on it, and it turned out the fridge was responsible for half her electricity bill.

She bought a new fridge for $1000, cut her bill in half, which another 6 panels would never have achieved.  I'm a lousy salesman......!  But I have very happy customers.

BTW......  if you own a McMansion, there are no rules about you having to occupy all of it.

http://damnthematrix.wordpress.com/2010/10/04/powering-up-for-the-collapse/

Mike


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goes211
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Re: Installing a Solar Energy System

Very cool.  Thx for sharing.

ao's picture
ao
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Re: Installing a Solar Energy System

Thanks so much for taking the time to put this all together for us.  It's a wealth of useful information and I greatly appreciate the time it will save me in some of my research. 

You've given me pause though.  The complexity of your system looks daunting to me.  Do you have any concerns about  potential difficulties with troubleshooting and fixing a problem?  It just seems like there is a lot that can go wrong and a lot of maintenance considerations but maybe I'm overly focused on simplicity.  Besides the normal Murphy-type maintenance glitches, do you have any idea of how your system would hold up to a lightning strike?

Your article has driven home to me even more the importance, for myself, of initial selection of geographical location, consideration of the local ecology, selection of community type, site selection, consideration of the skill and availability of local building and maintenance labor, consideration of the type of grid power available, short term vs. long term costs, etc., with particular consideration to home design.  Thanks again for an interesting article.

Damnthematrix's picture
Damnthematrix
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Re: Installing a Solar Energy System

ao wrote:
The complexity of your system looks daunting to me.  Do you have any concerns about  potential difficulties with troubleshooting and fixing a problem?  It just seems like there is a lot that can go wrong and a lot of maintenance considerations but maybe I'm overly focused on simplicity. 

You have to realise that this system is way over the top......  it doesn't have to be this complex at all.  KISS comes to mind!

Poet's picture
Poet
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Posts: 1836
Potentially Cheap Winter Solar Heating with Trombe Walls

I have books from the late 1970s that talk about passive solar heating. Some were able to get their homes heated to 80 to 90 degrees on a sunny winter day when the outside temperature was around freezing. And that's just with 1970s technology!

The most particular fascination I have (though I've never tried it) is with Trombe (or Morse) walls:
http://en.wikipedia.org/wiki/Trombe_wall

At the simplest, we're talking putting up dark screens and some nails to a window (probably under $50):
http://www.motherearthnews.com/do-it-yourself/solar-heating-zm0z10zhun.aspx

At the more complex levels, I've read about, which is what I linked to earlier, is a whole window or wall section (likely around $400 or so dollars):
http://www.motherearthnews.com/Renewable-Energy/2006-12-01/Build-a-Simpl...

More technical details:
http://www.builditsolar.com/Projects/SpaceHeating/SolarWall/SolarWall.htm

Poet

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Johnny Oxygen
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Re: Installing a Solar Energy System

If you are looking for a well illustrated easy to understand book on the subject of passive solar as well as sun and light I suggest this book highly. The Trombe wall is also dicussed and explained here.

Also look at the work of the Egyptian Architect Hassan Fathy. He is well known in the middle east for his work with passive solar heating and cooling with mudbrick buildings.

Johnny Oxygen's picture
Johnny Oxygen
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Re: Installing a Solar Energy System

Damnthematrix wrote:

ao wrote:
The complexity of your system looks daunting to me.  Do you have any concerns about  potential difficulties with troubleshooting and fixing a problem?  It just seems like there is a lot that can go wrong and a lot of maintenance considerations but maybe I'm overly focused on simplicity. 

You have to realise that this system is way over the top......  it doesn't have to be this complex at all.  KISS comes to mind!

Hey DTM this is essentially what you Aussies use on your roofs to heat your water. Its just a radiator in reverse. You can also stack 50 gallon drums filled with water next to each other and get the same effect. Water has a long 'lag' time for releasing heat so that is why it is used so often. Long time to heat it up and a long time to cool it down.

Damnthematrix's picture
Damnthematrix
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Re: Installing a Solar Energy System

Johnny Oxygen wrote:
ao wrote:
The complexity of your system looks daunting to me.  Do you have any concerns about  potential difficulties with troubleshooting and fixing a problem?  It just seems like there is a lot that can go wrong and a lot of maintenance considerations but maybe I'm overly focused on simplicity. 

You have to realise that this system is way over the top......  it doesn't have to be this complex at all.  KISS comes to mind!

Hey DTM this is essentially what you Aussies use on your roofs to heat your water. Its just a radiator in reverse. You can also stack 50 gallon drums filled with water next to each other and get the same effect. Water has a long 'lag' time for releasing heat so that is why it is used so often. Long time to heat it up and a long time to cool it down.

Absolutely not.........  I took one look at the housing the hot water tank is in, and thought.......  OMG!  What's with all that technology?

Guess which one is mine.......?

Mike

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buenijo
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Re: Installing a Solar Energy System

A solar thermal adsorption chiller would be ideal here. Check out www.sortech.de for a residential system.

I'm aware of a few small companies currently developing solar thermal power generation systems that are suitable for residential applications. I think thermal systems are ideal because they are not restricted to using solar. The small power generation system that I've seen are not terribly efficient, but making the most out of the available heat energy through efficient cogeneration more than makes up for it. I think decentralized cogeneration is the future. Fortunately there are many products on the horizon that will make it a reality soon.

See also:

www.cyclonepower.com (developing modern steam engines including a small unit rated at 5 hp specifically for solar thermal applications. Everything about this unit is ideal for residential cogen. The system is water lubricated with the liquid water sent to the steam exhaust after moving through the main bearings. This saturated water and steam is ideal for use with the chiller described above. The system could easily be aligned for both space heating and water heating as well. A natural gas furnace can always supplement solar. Also, Cyclone is developing a biomass-fueled system as well, and this ideal for those in areas of low solar incidence and/or off grid)

www.cogenmicro.com (another company working on a residential cogen system)

Johnny Oxygen's picture
Johnny Oxygen
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Re: Installing a Solar Energy System

Holy James Watts!

Looks like a Rube Goldberg set up. Wheres the mouse trap?

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Re: Installing a Solar Energy System

Who has one of the largest and most successful solar programs in the world? Germany. A country who gets about the same amount of sunlight as Alaska. It is false that solar energy is not practical in cloudy or northern climates.

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Dutch John
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Posts: 46
Re: Installing a Solar Energy System

Well, I live west of Germany and have pv panels. In winter they bring about 10% of summer gains. So if the system is not huge and you want to be totally off grid, you need additional power by wind and a backup generator. Nothing wrong with that, except for the complexity. 

Solar home heating in winter is nuts here. It works if you have a very well insulated home, but the amount of collectors needed is too large. Better redefine a home, like Ianto Evans did in his book "The hand-sculpted house". Size it to what is necessary. Use strawbales, cob and other local techniques. Then you will realize that a woodburner and one cord of wood a year is way cheaper, simpeler and much more reliable than a lot of high tech that only lasts until the next blip.

Small is beautiful.

Regards, DJ

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Damnthematrix
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energy efficient house in Swiss Alps
I haven't made may posts here in a while. I will attempt to do a few more ... 
This is a start, an underground house that I found to be quite interesting.  The house it's self is located in the Swiss village of Vals, and designed by Netherlands Architects SeARCH and Christian Muller Architects. I really appreciate both the circular nature of this home and the connected to the earth approach taken by the architects. A house that is part of the land rather than a figment on-top of the land, struggling against the land. This house works with the land. I will let the images speak for themselves.
 
 
 
 
 
 
rhare's picture
rhare
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Re: Installing a Solar Energy System

Sorry for the delay responding, have family in town for Thanksgiving so I'll try to respond to all the questions and comments so far.

Damnthematrix wrote:
"It may be that the incremental cost of a larger solar installation will be less expensive than usage reduction improvements you can make"

In my experience......  NEVER.

It's funny Mike,  when I put that in there I was guessing you would be the first person to make a comment. Never say never! Wink So let's look at some systems over a 10 year ownership, all these systems with grid tied SMA inverters, Schott 225 Panels, 50% of the material cost added on for installation (assuming cheap roof mounts):

 

System Size

Components

1kW (.9)

2kW

2.7kW

3.6kW

Inverter SMA (700U,3000,3000,4000)

1,085.00

1,995.00

1,995.00

2,470.00

Panels Schott 225W (4,8,12,16)

2,312.00

4,624.00

6,936.00

9,248.00

Racking, Installation (50%)

1,698.50

3,309.50

4,465.50

5,859.00

Total

5,095.50

9,928.50

13,396.50

17,577.00

         

Yearly Power Production (from PV Watts)

1,513

3,363

4,540

6,053

         

Total (less tax credits - 40%)

3,057.30

5,957.10

8,037.90

10,546.20

REC Credits ($0.13/kWh - 10 yrs

-1,966.90

-4,371.90

-5,902.00

-7,868.90

Power Savings ($0.08/kWh) -  10 yrs

-1,210.40

-2,690.40

-3,632.00

-4,842.40

10 year cost

-120.00

-1,105.20

-1,496.10

-2,165.10

 
 

So Mike, here in NM, with the incentives currently in place:  you're better off, over the next ten years, building the largest system you can.  The larger the system the better the payoff.  This works up to the maximum size for the small PV system from the utility company (10kW).  I did not say that this was long term sustainable - because it clearly is not, it is completely perverse incentives - but it is definitely not cheaper to reduce, in fact it will cost you more if you can stay with cheap roof mounting and a grid tied system.  This will not apply to all areas because incentives will vary.  I do know that NM has good incentives, but not as good as some places in California. Also, your cost of $6000 for the upgrade to your friends system is double the price here with incentives.

I was going to put this in the article, but cut it due to length. Our system is a large PV system.  We are paid $0.15/kWh for all the energy we use and consume, and about $0.04 for any excess energy we generate and sale back.  So until the "loss avoidance" rate goes above $0.15 we are better off wasting any excess energy we produce because it pays better.  Also note that when you transition from 9.99kW system to 10.0kW system, just the size change here is a $440/yr advantage due to the way the incentives work.

On the thermal side,   for us I know that most of the heat loss is through the uninsulated slab and windows.  Neither of which I can do much about.  The windows are already double pane high quality  windows.  While I could change them out to triple pane it would cost more than the entire thermal system.  The slab I can't do anything about.  Anything else I could do was dwarfed by those two factors.

Damnthematrix wrote:
BTW......  if you own a McMansion, there are no rules about you having to occupy all of it.

No you don't, but for many depending on the layout, not using it does not help.  For instance, our house is very open - so not heating one room simply sucks air from other rooms since we have very few doors/separation.  Again, depending on your situation it can vary immensely.  You have to spend some serious spreadsheet time to find the best financial outcome if that is your driving incentive.  If you simply trying to save the planet then just don't have kids and you'll be far ahead of most. Surprised

lexscripta wrote:
All of this is fantastic, where the average sun is around 300 days per year, as in New Mexico - but what about people who live in shaded areas, or in places like Illinois, or Wisconsin? Clearly such solutions as the article suggests probably wouldn't mean much without the benefits of a suitable geographic location.

While we have a big advantage in solar in NM, it might surprise you that solar is still an option in places like Wisconsin.  For example, a 4kW system in Green Bay, WI produces about 71% over a year as a system in Albuquerque, NM.  One in Anchorage produces about 50%.  These may still be viable depending on incentives, your energy costs, and your desire to hedge against energy prices.  The PVwatts site is really useful for analyzing production capacity.  Also, you need to keep in mind that there may be other alternative energy methods that work better in your area - wind, micro hydroelectric, geothermal.

greenmann wrote:
Who has one of the largest and most successful solar programs in the world? Germany. A country who gets about the same amount of sunlight as Alaska. It is false that solar energy is not practical in cloudy or northern climates.

Don't assume building solar systems in places like Germany is sustainable or practical (at least financially).  Germany has had massive incentives to build solar systems.  They could be large piles of dog doo and if you pay people enough to build them they will.  While it may be a long term beneficial thing to do, it is being done because those that take advantage are being paid very well to do so.  Just like the incentives I described above and in the article.  The solar incentives are a transfer of wealth from those who are capable of putting in system from those who can't or don't even look at it.  I mean here in NM, a grid tied system is easily a 10% ROI even if you provide nothing back to the grid (ie. you use all your own energy)!

Poet wrote:
For me, with a budget in the hundred dollar range (and being an apartment renter) ...
Poet, this article and they systems it outlines are definitely aimed at the home owner who has the financial ability to build such system and not in a position or able to alter the home to take advantage of passive solar techniques.  While some houses can be retrofitted, many can not, and I would very much advocate passive solar techniques in new construction.
Poet wrote:
If I became a homeowner (mortgage-holder?) then I'd start considering the cheap(er) solar alternatives - solar attic fan, solar hot water, a DIY Trombe/Morse wall (http://www.builditsolar.com/Projects/Spa... capable of providing 90 degree heat on a sunny winter day) , etc.
All of these are excellent methods to consider and it depends on your individual situation as to what is the best approach.  You have to remember there is only so much energy available on a given surface area from the sun so it will always come down to area available to collect the energy and efficiency of converting that energy to something useful.    For example, a well built trombe wall similar to what you showed in your diagram built at Zion National Park had an efficiency of about 13%.  For comparison the thermal solar system on our house is around 50% efficient.  So you would need about 4 times the size of Trombe wall as our collectors (520 sq ft)  to provide the same heat or a trombe wall of about 2000 sq. ft.    PV is really pretty bad at 16-18% efficient.
ao wrote:
You've given me pause though.  The complexity of your system looks daunting to me.  Do you have any concerns about  potential difficulties with troubleshooting and fixing a problem?  It just seems like there is a lot that can go wrong and a lot of maintenance considerations but maybe I'm overly focused on simplicity.  Besides the normal Murphy-type maintenance glitches, do you have any idea of how your system would hold up to a lightning strike?
Believe me, I have worried about complexity.  The system looks more complex than it actually is.  For example, on the PV, the 3 poles pictured are just like any other grid type system.  There is nothing special other than the size of the system.  If the system was 16 panels with 1 inverter would it be simpler?  No - just smaller.  When you get to adding batteries things get more complex. You either have a DC coupled system with charge controllers or an AC coupled system with inverters.   In our case I tried to keep things as simple as possible and still reach our goal.  With the thermal system, it's complexity is because it's both radiant floor heat and domestic hot water.  As far as domestic floor heat is concerned it's actually a much simpler system than many other people put in since it uses the slab instead of heat storage tanks.  As far as lightning.  There are ground rods and some protection - however it's on my list to figure out how to better protect the system from lightning and a potential Carrington event.
ao wrote:
Your article has driven home to me even more the importance, for myself, of initial selection of geographical location, consideration of the local ecology, selection of community type, site selection, consideration of the skill and availability of local building and maintenance labor, consideration of the type of grid power available, short term vs. long term costs, etc., with particular consideration to home design.
I would say all those items would be a consideration before you get to any of the concerns/systems outlined here.  If you can select your location and build, you can definitely build a more sustainable home - hence why I said our house "Not a model of sustainability". Tongue out  However, if you are going to stay in an existing home then systems such as ours are worth researching.
Damnthematrix wrote:
You have to realize that this system is way over the top......  it doesn't have to be this complex at all.  KISS comes to mind!
Damnthematrix wrote:
Absolutely not.........  I took one look at the housing the hot water tank is in, and thought.......  OMG!  What's with all that technology?

Mike I think you are confusing size with complexity.  "Way over the top" is I believe your response to the size of the system.  If we were trying to heat a small house then the system would be much smaller - however, we are heating about 75K cubic feet in a climate that does get cold (0F, -17C) not the balmy 45F (7C) you get down to in Cooran.   Also - the system looks more complex than if the plumbing closet were nice and neat with new construction.

It's probably better to look at the diagrams rather than pictures to get a feelig for the complexity of the system. The details of plumbing (valves, preassure tanks, pumps) in the picture all make it look much more complex than it really is.

My goal was not to say this is the solution, rather to point out what we have done.  I forgot to put in the article that being a trend setter at putting in solar, even small systems, can encourage others to do so as well.   After we installed the systems I had a big open house for all our neighbors with technical people from the vendors on hand to explain the system.  At least 4 people from the open house have now installed grid-tied solar systems on their houses. Laughing

Mike, I do like the house in the Swiss Alps, very cool.  With new construction and knowledge about the 3Es you can make much better choices in building.

ao's picture
ao
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Posts: 2220
Re: Installing a Solar Energy System

rhare,

Thanks for your replies and thanks again for sharing your experience.

DTM,

I like the house in the Swiss Alps.  My only question would be,  what about snow accumulation?.  Positioned on the side of a hill in a heavy snowfall area with a bowl type of configuration, I would think that the excavated area in front of the house would have a greater than normal snow accumulation. 

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we_are_toast
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Re: Installing a Solar Energy System

This is a very nice presentation of solar applications on the high cost end.  Unfortunately I think it might scare people into believing that solar is way out of their reach.  I'm kind of a do it yourselfer without much skill or money so I'm forced to do things in a different way.

I live in a very cold climate, 8500' in the Colorado Rockies.  Last week the wind chill was well below -40F where my weather station starts reporting an error!  

We designed and built our own entire 1800 sq ft house, off the grid, with passive and active solar, 1.2KW PV, and a small wind generator, for just about the price of what was the pre-credit costs of the solar systems discussed in the article.

The keys to doing it yourself, is to read a lot, talk to people, and of course, keep it simple.  If your thinking solar, think conservation first.  Every watt you save in efficient lighting and low energy appliances, is a watt you don't need in PV or wind production.  Every BTU you save in insulation, translates to a smaller heat source.  And think storage (thermal mass) to considerably lessen your heating costs.  And most of all, know your local weather conditions and use the building techniques and methods that best apply to those conditions.

earth bermed

The house is a simple rectangular design, with a very simple roof design.  Roofs are expensive.  The more complicated a roof, or the more twists and turns in the exterior wall, the more expensive will be the construction costs.  Plenty of windows to the south and east, only what's required by code on the north.  The house is bermed about 20" on three sides to reduce heating costs even more.  It is built using Insulated concrete forms, so the walls are 6" of concrete sandwiched between 5" of polystyrene for an R of 25 and some useful thermal mass in the walls.  We chose ICF's because they were easy to work with.  It's kind of like building with Lego blocks.

The floor is a concrete slab that rides on about a foot and half of sand, with it all being insulated from the ground with 2" of Styrofoam.  We then stained the concrete a dark color to help absorb the sun from the passive windows.  This is a very large amount of thermal mass and helps stabilize the interior temperatures very nicely.

kitchen floor

Typically there are 2 types solar hot water systems, antifreeze systems, and drain down systems.  In our cold climate I was very concerned about a failure in a drain down system causing severe damage to many components.  I also didn't want the complexity of a pressurized antifreeze system, so I built a hybrid system which is a partially closed, non pressurized  antifreeze system which is used solely to provide heat to the radiant system in the floor.  By providing heat to the thermal mass, rather than to a water heater, the system can run at a much lower temperature, and becomes a much more efficient use of the sun.

I don't want to distract from the fine presentation of the solar additions to the NM home, but I did want to point out that solar isn't necessarily overly expensive, and that with a little sweat equity, striving for self sufficiency can be well within most peoples budgets.  I think if we truly believe our energy an economic future is very much imperiled, we may find that doing more for ourselves will become a necessity.  We may also find that doing more for ourselves can be a very richly rewarding experience.

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Christine Baker
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If you're NOT loaded with cash

There are MANY ways to build solar water and air heaters for less than $100.

The complexity of this system is scary, how are you going to FIX it?

I really do like the house, it's just too bad it can't be turned around.  I would definitely CHANGE a few things to use the sun for heating.  A real adobe addition on the south side would go a long way.  I would also install a false ceiling for winter. 

Why not simply leave the recessed lighting off?   Light fixtures are CHEAP! 

We've been living off the grid since 2007 in our still unfinished house (convential framing) and we're still working on many changes.  Unfortunately I didn't learn about adobe until AFTER the exterior was finished.

We have LED lights (they work with dimmers) and they're perfect to provide enough light so you find your way around at night.  We leave them on in the hallway until we go to bed.  We have multiple light fixtures with different bulbs in each room, but of course one can get one of the plugin types without having to do any rewiring.

We added a little greenhouse on the south side built with adobe.  It's incredible how cool it stays in summer and that it always stays over 40 degrees even with single digit temps at night without any heating.

Today we'll hopefully finish our first solar air heater and we'll test it on the greenhouse addition.  If it works, we'll put vents from the addition to the house to help with heating there.

Cost: about $15 for lumber and a sheet of OSB (which we've already had for a few years).   For glazing we're using some old windows we recently got free.   It's not nearly as pretty as what you buy at a store, but consider the savings!  

We've been watching online videos on how to make all sorts of solar water heaters and air heaters. Especially PREHEATING water for regular water heaters is extremely cost effective.  But don't bother trying to make you own solar electric panels and don't pay for any of the ebooks that claim that it's so easy.  It's a ton of work and you don't save much.

It's a shame that so few builders consider free energy - our sun.  But as long as you have unshaded space on the south side of your house you should definitely look into SUPPLEMENTING with solar.  It's very inexpensive and even people in apartments with sunny windows or balconies can lower their utility bills.

Reading this article is like watching a TV show about the houses of the rich and famous.  It works for THEM, but the average person couldn't even pay the property taxes and maintenance.  Similarily, I know that we could not afford to maintain such a high tech system.  It's NICE, but not for us "little people."

I really wish I had known what I know  now a few years ago, but it's never too late to learn and make some changes.

Christine

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Re: Installing a Solar Energy System

we_are_toast wrote:

I'm kind of a do it yourselfer without much skill or money so I'm forced to do things in a different way.

we_are_toast,

I don't know about not having much skill.  Building a house (and one off the grid for that matter) is quite an accomplishment in my book.

I like what you've done.  It's simple but well thought out.  The older I get, the more I appreciate the virtues and benefits of simplicity.

I have a couple of questions, if you don't mind.

Any particular reason (other than cost savings) that you built the house on a slab in a cold weather area rather than building a basement?

Is that a metal roof?  If so, knowing how snow slides, any particular reason you built the garage doors on the front of the house rather than the side? 

What type of siding did you use?

Is that a propane tank I see and if so, what percentage of your  does it supply in the winter?

Thanks for any help and for your fine contribution.  I, personally, would like to hear more about your house and your ideas.

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Damnthematrix
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Re: Installing a Solar Energy System

rhare wrote:

Sorry for the delay responding, have family in town for Thanksgiving so I'll try to respond to all the questions and comments so far.

Damnthematrix wrote:
"It may be that the incremental cost of a larger solar installation will be less expensive than usage reduction improvements you can make"

In my experience......  NEVER.

It's funny Mike,  when I put that in there I was guessing you would be the first person to make a comment. Never say never! Wink So let's look at some systems over a 10 year ownership, all these systems with grid tied SMA inverters, Schott 225 Panels, 50% of the material cost added on for installation (assuming cheap roof mounts):

 

System Size

1kW (.9)

2kW

2.7kW

3.6kW

         
         
         

Total

5,095.50

9,928.50

13,396.50

17,577.00

         

Yearly Power Production (from PV Watts)

1,513

3,363

4,540

6,053

         

Total (less tax credits - 40%)

3,057.30

5,957.10

8,037.90

10,546.20

REC Credits ($0.13/kWh - 10 yrs

-1,966.90

-4,371.90

-5,902.00

-7,868.90

Power Savings ($0.08/kWh) -  10 yrs

-1,210.40

-2,690.40

-3,632.00

-4,842.40

10 year cost

-120.00

-1,105.20

-1,496.10

-2,165.10

 

So Mike, here in NM, with the incentives currently in place:  you're better off, over the next ten years, building the largest system you can.  The larger the system the better the payoff.  .

You're not telling me anything I don't know here.......  I do this for a living.  We are talking at cross purposes here.  I wasn't saying that building a bigger system won't save you money (or even make you money), I'm saying it's ALWAYS cheaper to find ways to reduce electricity consumption than to generate your wastage by any means, whether coal fired or PVs, but especially PVs.

In the last 12 months we have reduced our consumption (according to the last bill I'm holding in my hot little hand) from 4.98kWh/day (an already very low level of consumption) to just 2.13kWh/day........

How did we achieve this?  With a hyper efficient fridge that only cost us $700 (it's in my blog - link below), switching from satellite internet to ADSL (the old modem consumed 60W continuous, the new one so little we never bother to turn it off), switching from a 130W PC to a 30W laptop, and ditching the old 150W CRT TV to a 50W LCD digital unit (only 23")

If you've been following anything I write about what we've done, you'll know we've had 1.3kW on the roof for over 5 years, and that we have recently added another 2.2kW - just as an investment.  Both systems are now feeding the grid through a SMART METER.  We get 52c/kWh for any excess (ie that which we don't use, which is like 90%) and only pay 21c for everything we import (like at night).

The result is that we will make ~$2000 a year profi out of this, which is MORE than what you will make out of your system which is three times the size of ours.  Now tell me energy efficiency doesn't pay?

rhare wrote:
Mike, I do like the house in the Swiss Alps, very cool.  With new construction and knowledge about the 3Es you can make much better choices in building.

Yes it is rather cool...  I only found it three days ago, and it was love at first sight!

3Es or no 3Es......  there's no excuse for building the crap housing stock currently going up all over the world.  I've known about building truly amazing houses for twenty years, so why doesn't anyone build them..?  Sigh..

Mike

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Re: Installing a Solar Energy System

ao wrote:
DTM,

I like the house in the Swiss Alps.  My only question would be,  what about snow accumulation?.

There are pics of it in snow here http://www.christian-muller.com/CMA.Projects/VVW/180-ArchRecord.pdf

Mike

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Re: Installing a Solar Energy System

we_are_toast wrote:
This is a very nice presentation of solar applications on the high cost end.  Unfortunately I think it might scare people into believing that solar is way out of their reach.  I'm kind of a do it yourselfer without much skill or money so I'm forced to do things in a different way.

Thanks for sharing pictures of your system.  I was a bit worried that it would scare people as well, that's why I pointed out that the systems are scalable to any size house.  Our house is large and not designed with energy efficiency in mind when it was built (we didn't build it).  If you have a smaller house, or are building and design with energy issues in mind you can definitely get by with a much smaller and less expensive system but the basics of how it works should be about the same. 

The systems needed to support a house will be roughtly proportional to the size of the house. For example, for heating, you have 1800 sq. ft with I'm guessing 8' ceilngs based on the picture for a total heated volume of 14,400 cubic feet, we are heating roughtly 5 times the volume with our system. On the radiant floor heat, our house was designed with a convential boiler, so the radiant floor doesn't work well with water less than about 140.  As you said, if you have a well insulated slab, proper radiant piping (even, fairly close runs, and close to the surface of the concrete and well balanced zones), you can get away with lower temperatures.  Our house has actually been a bit of a problem child for the controls folks because of the radiant floor was not designed with lower temperature solar in mind. The radaint floor/indirect water heater are pretty much identical to what you would find in many houses without solar.  The solar simply adds another heat source.  If you happen to try to do dual fuel (electric, gas, wood) heat sources you would probably have a very similar setup.

I'm guessing with your PV, wind, and being off grid, your PV setup may actually be more complicated than our system. 

Christine Baker wrote:
There are MANY ways to build solar water and air heaters for less than $100.

The complexity of this system is scary, how are you going to FIX it?

There are always ways do do things on the cheap as a DIY.  However, in the case of cheap hot water systems and air systems they have their limitations.   With air systems, you only get hot air during the day, and little to no heating at night unless you are using hot air to heat a mass.  However, if you are trying to do that, a thermal hydronic solution is much more efficient and will require less collector surface area.  Cheap water heating systems are easy to build in climates without freezing temperatures, but once you get freezing it complicates things a bit.  You either have to drain water out of collectors or use a separate loop filled with antifreeze (glycol) and a heat exhanger (exactly what our system does).

The system is not very complex and I feel I could easily work on any of the components with basic plumbing skills.

Christine Baker wrote:
Why not simply leave the recessed lighting off?   Light fixtures are CHEAP!

We could, but I don't want too.  It would seriously impact the aesthetics of the house. Wink  It's kind of like why do you want windows in a house -  without any you can really cut down on your heating bills - but would it be as pleasant to live in?  On the LED lights, they have become better and cheaper recently.  There are now some recessed can replacement lights by  Cree that have the same light quality as a traditional halogen 75W bulb and work well with conventional dimmers   The problem is they are still very expensive ($75/bulb).  I tried CFLs in some areas and they are not near as pleasant a light source so I'm waiting a bit to see if the price will come down and I will look at replacing the halogen lights we now have.  Then we will have excess power for an electric car/motorcyle.  I'm also much less worried about excess generating capacity from the PV.  In an energy crisis, having excess power to use or sell will be a nice problem to have.

Christine Baker wrote:
Similarily, I know that we could not afford to maintain such a high tech system.

I actually anticipate very little maintenance. Clean off the panels and collectors once in a while and change the thermal glycol every 5 years or so.  That should be all the maintenance.   The thermal system is really not any more complex than our old radiant floor/DHW system.

DamnTheMatrix wrote:

I do this for a living.  We are talking at cross purposes here.  I wasn't saying that building a bigger system won't save you money (or even make you money), I'm saying it's ALWAYS cheaper to find ways to reduce electricity consumption than to generate your wastage by any means, whether coal fired or PVs, but especially PVs.

...

The result is that we will make ~$2000 a year profi out of this, which is MORE than what you will make out of your system which is three times the size of ours.  Now tell me energy efficiency doesn't pay?

Cheaper - but not better financially. As shown, you could save money by conserving, however, if you have money that is sitting in a bank account, you would be better off spending on a larger solar system and making more money than you would keeping it in the bank.  Also, depending on the incentives rules, it looks like that would be even more true in Australia.   With the dollar at parity, your electric rates are 2.5 times more than ours and your incentive is 3.5 times more.  With incentives like that I would be building as big a system as I could!  After all, if I can invest  6000 and have it paid off in only 3.4 years and the rest of the 25 year life is income, why wouldn't you do so? 

DamnTheMatrix wrote:
The result is that we will make ~$2000 a year profi out of this, which is MORE than what you will make out of your system which is three times the size of ours.  Now tell me energy efficiency doesn't pay?

Actually our system has a net return of about $4,350/year. Savings on power purchases is $1,800 of that, the rest is REC credit incentive.

DamnTheMatrix wrote:
3Es or no 3Es......  there's no excuse for building the crap housing stock currently going up all over the world.  I've known about building truly amazing houses for twenty years, so why doesn't anyone build them..?  Sigh..

Same reason very few people know about the 3Es or fiat currencies. The way I see it, the houses are built, it does no good complaining about how crappy they are or how it would have been better .... It's now a situation we have to live with and you make do with what you have and hope to influence better designs going forward. While that house in the Swiss country side is nice looking, built into the side of the hill, as far as a sustainable option I suspect the house we_are_toast built is much more sustainable/realistic for the future. Although with a mostly underground house you can start to work with seasonal thermal stores.

DamnTheMatrix, we_are_toast and Christine Baker - you should definitely work on posting the solutions you have developed and show costs and labor involved.  I'm sure many of the readers here would like to see the performance and cost information on your systems. 

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Re: Installing a Solar Energy System

ao wrote:

we_are_toast wrote:

I'm kind of a do it yourselfer without much skill or money so I'm forced to do things in a different way.

we_are_toast,

I don't know about not having much skill.  Building a house (and one off the grid for that matter) is quite an accomplishment in my book.

I like what you've done.  It's simple but well thought out.  The older I get, the more I appreciate the virtues and benefits of simplicity.

I have a couple of questions, if you don't mind.

Any particular reason (other than cost savings) that you built the house on a slab in a cold weather area rather than building a basement?

Is that a metal roof?  If so, knowing how snow slides, any particular reason you built the garage doors on the front of the house rather than the side? 

What type of siding did you use?

Is that a propane tank I see and if so, what percentage of your  does it supply in the winter?

Thanks for any help and for your fine contribution.  I, personally, would like to hear more about your house and your ideas.

When I say I'm not very skilled, I really mean it.  I'm not a carpenter or a plumber, or an electrician, but if you read a lot of books, and talk to a lot of people who are skilled, and you keep it simple, you'll be amazed at what you can do.  Another big help was our county building department.  Inspectors can be a real pain sometimes, but if you talk to them before you do something, and show them exactly what you've got planned, they will often make suggestions that will make it easier and will meet the code without any problems.

I'm not saying building yourself isn't a lot of work, it most certainly is.  But if you know it's going to be a lot of work, you can plan accordingly, and it can be a very satisfying type of work.

You have some excellent questions.

I didn't build a basement for a couple of reasons.  One was the cost.  Instead of a deep foundation and footings below the frost line, I went with a very shallow footings, approx 2 feet, and a frost protected foundation.  A frost protected foundation consists of sheets of Styrofoam that extend 4' horizontally  from the top of the footings.  The second reason was the thermal mass.  I wanted a large thermal mass and using the floor was an easy way to get it.  The sand and concrete give me approximately 30 tons of thermal mass in the floor.  This means when it's 0F outside, the temperature inside will drop about 8F over a 24 hour period.   On an average January day, if it's sunny, we'll go 24 hours without using any auxiliary heat source.

Yes, it is a metal roof.  The area I live in is very, very windy.  It's not uncommon to have 70 and 80 mph winds.  The winds are primarily from the southwest, so the garage doors face away from the wind.  Most of the time, the snow will blow off the roof.  When it doesn't, I get my daily exercise shoveling snow.

The siding is hardy plank fiber cement siding.  Colorado is currently undergoing an environmental catastrophe.  The winters simply don't get cold enough anymore to control the pine beetle.  I've watched about 90% of the trees in our valley die in the past 3 years.  We are keenly aware of the potential for fire.  Although a log cabin in the mountains sounds rustic and romantic, I'm betting my metal roof and fiber cement siding will mean my house will be one of the few left standing after a fire.

We have a very small wood stove we use to supplement the sun for our heating.  The propane is used for water heating and for cooking mostly.  We also have a propane fireplace with a thermostat we use when we're gone for more than a day.  We do not have a furnace.  Last year we went through 2 chords of wood and about 70 gallons of propane.  I had quite an argument with our propane dealer.  I wanted a 500 gallon propane tank and he insisted that I needed a 1500 gallon tank for the size house I have and the weather conditions up here.  Since the area can be very difficult to get in and out of in the winter, he told me he would refuse delivery when I run out of propane in February.  I told him not to wait for my call.

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Re: Installing a Solar Energy System

we_are-toast,

Thanks for the excellent information.  I also live in a snowy, cold weather area and have forest fire concerns as well so your information is definitely useful.  After having built the house, is there anything significant you would have done differently?

P.S.  I'm impressed by you not having those particular trade skills and taking on and finishing a project of that magnitude.  You're an inspiration!

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Re: Installing a Solar Energy System

ao wrote:

we_are-toast,

Thanks for the excellent information.  I also live in a snowy, cold weather area and have forest fire concerns as well so your information is definitely useful.  After having built the house, is there anything significant you would have done differently?

P.S.  I'm impressed by you not having those particular trade skills and taking on and finishing a project of that magnitude.  You're an inspiration!

There are always things that I think I could improve on.  Some, because I'm curious how a different approach would have worked out, and others simply because my lack of experience caught up with me.

I certainly underestimated the number of thermal solar panels I needed to warm up the large thermal mass I have in the floor.  At some point I'll probably double the number of panels.  I would also give more thought at mounting the panels prior to putting the metal roof on, and may even consider mounting panels in the roof rather than on the roof.  With the cold wind, I might also consider vacuum tube collectors rather than flat plate collectors.

I would run individual 1/2" hot water lines to hot water outlets rather than using a branch system.

If I didn't live in a high wind area, I would consider a super insulated, double wall frame construction technique rather than the ICF's.  There really are so many different methods to massively improve energy efficiency and reduce your carbon based energy usage that people really have the option of choosing what is best for their local conditions, needs, budget, and abilities. 

Rhare has really presented some great information about his approach to his situation in wonderful detail.  He is also very correct in that system size, approaches, and costs can scale.   I might consider his approach as a Cadillac method, and my approach as a Hyundai method.  My 1KW off grid PV system, my small wind generator, and my 100 ft^2 thermal system cost roughly $13,000 before credits and + my time.  I hope others can find some place in between our approaches or maybe an entirely different approach that will meet their personal needs.

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Re: Installing a Solar Energy System

I was at the Lowesville Seminar also.  I probably saw you there.

I live in Virginia and the panels that we have here are working just fine. We put up 6 kW solar thermal/hot water panels first and then a string of 4kW PV.  We then moved to the micro inverter panels which are more efficient.  We put up 8Kw PV on the garage and then, because we had solar credits for one more kW (what the heck), we put up 4 more panels this month. We do not have batteries. They decrease efficiency, don’t last very long, and are expensive.  The system will allow us to add them on later.

My husband is the “go to guy” for this project, but I can tell you, it doesn’t look very complicated. There are no moving parts and should be no maintenance. I see an extra electrical box on the wall and another water tank in the basement. I also see the meter running backwards all day.  Sweet.

The initial cost of the project was $70,000.  After state and federal rebates the cost was around $30,000. With SREC payments each month and savings on electricity, the payback period should be 5-6 years.

The key to this cost efficiency are the state and federal rebates.  There was a small window for getting the rebates here in Virginia (24 hours on the first go round).  The federal rebates will last until the end of the year. The fed rebates alone will save a third of the cost, which will certainly make the project a lot more affordable.

One other thing I will pass on, if you do this project, shop around for the best contract for the SREC paybacks.  The first solar installer, who we didn’t like, signed us up for a five year contract which gives him a payout (kickback?) of 100.00/mo.  There was so much going on and everything was so new, we didn’t know we could shop around for rates.   The next time around we got a month to month rate at a higher payout.

I hope you find this information helpful. 

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Re: Installing a Solar Energy System

This is a wonderful and well written description of the details that eluded me when I put in our PV and solar Thermal system with a natural gas generator backup.  The generator  has a cut off switch for power outages but I put it in AFTER the PV system and I am not entirely sure that in case of power outage, our system will be able to generate power from the PV in addition to the generator.  Having a mini grid Island is just what I needed to know.

My next project is to build an off the grid capable apartment in a new barn on my newly purchased small farm.  I have already forwarded your article to my architect! 

Thanks for taking the time to share your valuable experience with us.

Mark

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Re: Installing a Solar Energy System

Kayje wrote:

The federal rebates will last until the end of the year. The fed rebates alone will save a third of the cost, which will certainly make the project a lot more affordable.

Point of correction......the federal solar tax credits run thru 2016 as of right now.

The credits that end this tax year are for improvements like high effeciency appliances, windows, etc.

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Re: Installing a Solar Energy System

TNdancer wrote:

The credits that end this tax year are for improvements like high effeciency appliances, windows, etc.

The latest Senate tax cut bill extends those credits, with some changes.  Most observers think a tax

cut bill will pass (after some modifications by the House of Representatives).

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Energy Upgrades

This is all well and good if you have Thousands of Dollars and a Large House in the Desert.

How about if you are poor and have a small apartment with 3 narrow windows and want Photo Voltaics to power a 625 watt machine that cycles to 100 watts several times a night? A Kill-A-Watt is coming next.

I have already Cut our Energy Usage to the bone. If I could knock $20 off our electric bill in Hawai'i by powering this Peritoneal Dialysis Machine with solar panels it would make my day. I don't care if I only get 6 days a month of relief from HECO with this machine.

I have room for 9 panels @ 20 watts each with a full 6 hours of sun almost every day. Wish it could be more.
I have a Zantrex Sine 2000 inverter.
Charge controller is on the way.

Battery size and number is the problem. I don't know what size battery(s) to get.

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Do what you can....

Dr. Bill wrote:

This is all well and good if you have Thousands of Dollars and a Large House in the Desert.

We were fortunate to have a great situation for solar and the funds to do so, however, it sounds like you have in mind what is feasible with your housing and financial situation.  Just being aware of the three E's and thinking about what you can do puts you way ahead of most people.

Dr. Bill wrote:

I have room for 9 panels @ 20 watts each with a full 6 hours of sun almost every day. Wish it could be more.
I have a Zantrex Sine 2000 inverter.
Charge controller is on the way.

Just be aware that the full sun does not mean full output.  You only get peak output when the panels are perfectly perpendicular to the suns rays.  So on a fully sunny day you will get a bell curve with the peak output sometime around noon.  You also take hits for days your panels are not at the exact right angle.

You should play with PV Watts, the link is in the article.  It will show you your expected output when you put in the angles of your intended mounting.  If you use the default de-rate factor you'll probably be okay.

You won't be able to size your battery until you know your expected output/draw.  This last year at CES, panasonic had a display of a modular lithium ion battery pack system for solar.  Not sure if it's available yet, but it might be worth checking into.  You might also want to check into one of the pre-built solar backup kits.  I know people discussed them in the forums, so a few seachs might be useful.

Good luck, and I would encourage you to post your solution since you are not alone.

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Very nice and thorough

Very nice and thorough explanation. We have installed double axis tracking system at our place and it has proved very cost effective for us.

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Oliveoilguy
Status: Gold Member (Offline)
Joined: Jun 29 2012
Posts: 314
Zero Electric Bill Last 2 months

Can you share some details of your system?

I've got a GS8048 inverter with 18 sharp 240 w panels with battery backup,  and on another building some enphase 215's selling back to the grid.  We have a total of 10kw of array. Almost self sustaining at this point. However the summer months coming up with AC are high usage for us in Texas. If we can conserve through those months, we might consider going totally off the grid. 

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