First Off-Grid Solar Freezer (for Dummies)

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  • Thu, Jul 03, 2014 - 06:06pm

    #21
    Mots

    Mots

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    “Can you link to some that may be out there” (starting caps)

The Supco brand seems most popular (SUPCO HS6 (SPP6) Hard Start Relay Capacitor) and the bigger  (most cost) the better.  These are for the AC motor at 120 volts or higher.  If you have all 12 volt or 24 volt system: I would use a stereo power capacitor (Walmart sells a giant one rated at more than 24 volts) to put in parallel with the power lead to the low voltage DC motor.  BTW there are starter circuits for pumps that do a similar job of helping water  pumps alleviate high pulse starting and can get a water pump to operate off solar panel directly without a battery so if you want to run a pump directly off a solar panel and the starting juice isnt there, you have that option too.  futurlec.com sells a kit  for the latter.  best wishes

  • Thu, Jul 03, 2014 - 07:52pm

    #22
    Mots

    Mots

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    Super starting caps: correction

Correction: the super starting cap is AC so the leads are NOT + and – (no polarity).

  • Thu, Jul 03, 2014 - 08:35pm

    #23
    MoonShadow

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    Direct PV refrigeration, without batteries.

Yes, it can be done.  Much cheaper than with a dedicated battery storage bank, as well.  The SunDanzer DDR165 is designed to run directly from a solar panel with a 120 watt minimum rating, and uses "holding plate" style ice packs built into the walls for storage of "cold" energy.  It's a 5.8 cubic foot cavity, and it can be set to be a true freezer (if you have the sunshine to support that, which ups the solar requirements hugely) or a refrigerator, but not both at the same time.  I believe it's priced around $1600 before shipping.

 

  • Fri, Jul 04, 2014 - 06:23am

    #24

    sand_puppy

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    My Conversion Experience (DC to AC)

My understanding of "the best way" to set up a small, grid-down, type of system for my home to run a few essential appliances such as a freezer, is evolving with this discussion and ongoing reading.  

I think that I'm coming around to the view that Mots just articulated above:

1.  Lots and lots of solar panels

2.  An inverter to make DC current into AC

3.  Using "normal" AC household appliances and electric shop tools because they are 1)  ubiquitous and common, 2)  much much less expensive than their DC counter-parts, and 3)  I already have many of them (such as a freezer, table saw, LED lights and a washing machine).

The advantages of keeping the electricity DC (the way it comes fresh out of a PV panel) seem to have diminished with the falling price of panels.   The losses that result from the DC –> AC conversion fade in significance when a few more cheap panels are added on.

One poster here, about a year ago, indicated that the had set up an entire wood shop in a shed in his yard with solar panels directly powering ONE outlet in his shop that permitted him to use one electric tool at a time during daylight.  His wood shop was entirely off-grid.  His secret was Lots of Panels, an Inverter, and being comfortable restricting his woodworking hobby to daylight hours.

—————————————-

A request from those of you who have done this successfully:  Beginners need specific information.

1.  Show us which panels you are using?  Where did you buy them, which size, what connectors.

2.  Show us how you mounted them and what connection hardware you used? 

3.  Which charge controller and inverter are you using?  Specific model?  Where did you buy it.

4.  Which batteries? (Please give a link.)  Do you house them?

5.  Which super capacitor?  Do you need one for each motor and water pump?  Which model, how much money are you spending?

6.  How big is your system?  What appliances do you run off it?

7.  Can you link to a wiring diagram?

Thank you for taking the time to show us what you have done with enough detail so that we could retrace your process.

 

  • Fri, Jul 04, 2014 - 09:12pm

    #25

    sand_puppy

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    Mots: Are these the panels?

The company website for Sun Electric in Miami:  http://sunelec.com/

Which are you using.  It sounds like they would like to you buy a pallet at a time, but I can't find the number of panels on the pallet or the price for a pallet.

1.  http://sunelec.com/datasheet-library/download/sun/SUN-85-95_ce8tra8los.pdf

or these,

2.  http://sunelec.com/datasheet-library/download/sun/SUN-SF-SERIES-THIN.pdf

or these?

3.  http://sunelec.com/datasheet-library/download/sonali/Sonali_Solar_240-SS_230-240-250_Series.pdf

This third link mentions "high efficiency in diffuse light condition"s and "amorphous" and "thin film."

  • Sun, Jul 13, 2014 - 03:17am

    #26
    Rwrek

    Rwrek

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    Insulating Freezers

I am running a small ac freezer with a solar system(inverters, charge controller, etc) in a very hostile environment (Texas heat) and the insulation question came up.

I learned that many freezers use their outside metal surface to dissipate heat (unlike many older ones that had coils on the back to aid cooling). This means trying to insulate a freezer may actually be preventing it from cooling properly.

Research this subject for further details.

I have had to settle for making sure space was clear around the freezer and "brute force" battery power and charging capacity was available. Even then I have to wind up supplementing the charging of the batteries for cloud cover lasting too long.  Not ideal for grid – down possibilities.

If you find ideas that work, let me know.

Great info from Sand Puppy though.

 

 

 

  • Sun, Jul 13, 2014 - 07:30pm

    #27

    sand_puppy

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    Going in on a Pallet of Solar Panels?

I am contemplating buying a pallet of high quality solar panels and would like to know if any pp'ers on the east coast would like to go in with me.  A pallet is 30 of these BIG 275 Watt panels.  I would like to keep 8 – 10 myself.  Would anyone else like to participate in this bulk purchase with me?  Please PM me if interested or want to talk.

I live in Charlottesville, Virginia and would be willing to drive a couple hundred miles (to West Virginia, Washington DC, Maryland, North Carolina) to distribute them to others.  If people lived beyond this radius, we might be able to figure out a two person hand off.

Here is the website and page for this panel

http://www.wholesalesolar.com/products.folder/module-folder/SolarWorld/sw-275.html

And, here is the product specification sheet for this 275 Watt panel.

They are 66" x 38" and have a metal frame.  Weight is 47#.  "24 Volts" DC.  Rated at 275 Watts each (Much bigger than the 100 Watt panels discussed in my freezer post above.)  Cost will be $275 (for a 275 Watt panel) plus shipping to my house (which is yet to be determined).  This is $1 / Watt!!

They are Mono-crystaline (the higher quality design), made in the USA (not China), and seem to be from a very high quality and reputable company according to the reviews I have found.

—-

Professional quality mounting of PV panels is now about as expensive as the panels themselves.  To save money, I am personally intending to mount them myself, on the ground, with frames that I make inexpensively.  Should the grid go down, I'll get very busy building mounting racks quickly!  Here is a picture of someone's low tech mounting arrangement.

And a much more expensive arrangement:

Smaller ground mounts:

I have been won over to the approach of purchasing "too many" panels so that I can tolerate imperfect positioning, intermittent shade, overcast weather, and all the other inefficiencies from a system that is not laid out too perfection (which I cannot do at my house).  I don't have a perfect south-facing roof and the large shade trees (which are most welcomed in the Virginia summer) leave no section of our home or yard sunny all day.  I'll need to cluster panels in 3 different groups spread out through our yard in order to have PV power all day.

Since I am prepping, I'll keep several in my basement in reserve for the day that they are suddenly needed.   I will use PV power to pump from a rainwater collection tank to my garden.  

Possibly a neighbor may want to run their freezer also.  You know, one of those people who were sure that "nothing like this could every happen…." 

 

  • Sun, Jul 13, 2014 - 08:11pm

    #28
    James Knight

    James Knight

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    This is my rainwater

This is my rainwater collection system Sand_puppy. It doesn't need a pump as it works on gravity. You can just about see the yellow timer below which waters my hydrangeas for 5 minutes every evening.

  • Sun, Aug 10, 2014 - 03:57am

    #29
    johnln

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    Solar powered freezer

This is my first entry onto a forum. I started with a new medium chest freezer using a Danfoss BD50 compressor. The compressor is running off a solar system array of 1.5 KW feeding into a 700-amp hour 24-volt battery bank. The charge controller between the solar panels and the batteries is an Outback MX60. I have built the freezer into the house and am not using the built in condenser. This saves floor space, allows for an external condenser to heat water and dissipate waste heat outside the house and triple the insulation around the freezer. To minimize cost, voltage drop and copper cable I have used a ring circuit. This is commonly used in the UK. The BD50 compressor is designed for R134a gas. This is a synthetic gas and has been linked to cancer. I charged the freezer/compressor with a mix of isobutane and propane and changed compressor synthetic oil to pure mineral baby oil. The 24-volt power system also powers all of the lighting in the house using 12-volt strip LEDs and DC-to-DC converters. This system powers all other low voltage devices including a modem, desk top computer, phone chargers, anything else that had a wall plug transformer and even charges an electric bike.

I had no prior experience with refrigeration. All the systems have been functioning perfectly for 4 years. Almost all learning was through the Web.

Danfoss has a controller for running the BD50 and BD35 compressors directly from solar panels. Look up Secop solar panel powered BD compressors. 

  • Sun, Aug 10, 2014 - 09:54am

    #30

    Boomer41

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    A more general approach.

May I humbly submit that a solar powered freezer is just a sub-set of the larger problem of keeping a household functioning off grid. If you need a solar powered freezer you probably also need a solar powered TV, microwave, lighting and communications. I believe it is simpler (and possibly cheaper in the long run) to make a battery-powered, whole-house power system which provides 120 VAC, just like the utility company, and can run whatever you plug into it. No special DC motors required, just off the shelf appliances.

This can be achieved with a nice, big fork-truck style battery and an inverter to convert battery power to 120 VAC. All appliances are then plug and play.

The battery can be charged from solar panels, wind power, the grid (when it is on) or a small generator when it isn't. In all cases, bigger is better, so the highest capacity battery and most solar panels you can afford is the way to go.

Nothing about this system precludes the efficiency improvements of extra insulation or an external condenser on the freezer, it just makes the whole endeavor much easier.

See my posts at https://www.peakprosperity.com/blog/portable-solar-generators-hybrid-emergency-back-systems/71154 for more details.

 

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