Battery / Energy Backup for Solar Power Systems

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  • Sat, Feb 22, 2020 - 10:48am

    #1

    shawns333

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    Battery / Energy Backup for Solar Power Systems

I didn’t see any posts, at least nothing recent, about backup systems for solar energy systems. Would love to hear about what folks have done in this space, experiences, what worked well, what didn’t, etc.

I’m researching a solar system for home right now and given that I live in California and PG&E is our utility, I want to not only be able to leverage solar as a renewable and independent power source, but I also want to make sure my plan is resilient and my energy production doesn’t stop because of planned or unplanned outages.

I’m considering the latest AGM battery systems but I’m also curious about the Tesla Powerwall. Would love to hear all experiences and thoughts on this topic.

  • Sat, Feb 22, 2020 - 03:46pm

    #2
    last two

    last two

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    Reply To: Battery / Energy Backup for Solar Power Systems

Hi

We have a LG/ Enphase grid tied system and really like it. Enphase is suppose to come out with a system called ensemble this year that will allow for ac batteries charged with the solar panels. May be a little less expensive than powerwall.  Overall the solar is great. We live in Canada so winters do not produce much power summer spring and fall rock. LG also has a battery system

 

  • Sat, Feb 22, 2020 - 04:02pm

    #3
    mntnhousepermi

    mntnhousepermi

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    I have one

I have had a grid-connected, battery back up solar system here in California for 21 years.  I have what people now consider to be a “small” system, but it has always been sufficient for our needs here.

I have an all electric house, but I never use the electric heat, I only use the wood stove, and I have a very modern, low particulate air tight wood stove.  I had to replace last year, and now have a Lopi Endeaver.  I also put in a closed loop solar hot water system, as I have electric hot water heater.  I could bring in gas, propane, and run a hot water heater and cooking stove off of propane, which is how everyone else around me gets thru our seasonal power outages ( I live in an area that gets multi day outages due to bad weather,  the wind storm the other week left us without elecricity, internet or phone line for 3 days. ) so I have had practice before PG and E started the planned outages.  So, when the electric grid is down, I cannot use my electric stove or hot water heater.  Since it is only for a few days,  I just heat food and water on the wood stove, in general.  I also make use of many small appliances to cook, since I do have battery back up, like the electric kettle for hot water for beverages,  the toaster, bread machine, etc… I have a stand alone portable single induction burner I could plug in to cook on, but I have never bothered.  Maybe now that we have PG and E planned outages when it is hot, I might.  Last one I just used the solar oven outside.  I do run the water pump off of the back up batteries ( I am on a well and have a water tank with a pressure pump) .

 

So, my original system had 24 110Watt ( label rating) panels on the roof, for a “real” 2kWatt after the inverter, system.  I added another couple panels on the unused half the inverter 7 years ago, so now have around a net of 2.5kWatt.  My inverter is a Trace SW4048, from back when they were built in California and it has been working for the 21 years also, as well as charge controller.  The same SW4048 architecture is still available for sale from a different company name, as buy outs happened over the years ( I think it is currently Schneider ? ) .

So, my system is a 48V DC system.  I used to have Trojan lead acid solar batteries, 4 of them.  maybe the whatever 16’s.  I killed my batteries thru neglect when I became ill, otherwise I highly recommend the tried and true trojan lead acid batteries, or the Iron Edison.  The Iron Edison ( nickel/Iron) can last forever ( with some kind of electrolyte replacement or something every decade ?  Look it up.  I am not healthy enough to be able to do this, so I dont have them, but I think they are likely the best ) The batteries I got last time were Aquion, which is a salt water electrolyte, carbon/maganese.  I have 3 48V S-stacks, but 4 would have been better, each are 2.2kWh.  https://www.solarelectricsupply.com/solar-components/solar-batteries/aquion-energy-aspen-batteries/aquion-aspen-48s-2-2-ahi-saltwater-energy-storage-battery    You cannot buy them in the USA right now as they were bought by a company that took it to China.  I have been happy with them, they work well, and it is true that you can discharge all the way to nothing and not harm them,e tc…

I do not like the power walls or other lithium ion for home use.  For many reasons.  The advantage of these batteries for mobile applications like car and electronics are irrelevent to home use where weight and size are not considerations,  certainly not enough of a consideration to make up for how expensive they are.  The other thing I did not like about them is how dangerous they would be in a fire.  And, also, how they need a tighter temperature range, so they would be unhappy in my location, in my garage where it would be too hot for them, and I would need to use power to cool and heat during parts of the year.  It turns out that the cars do use power from the batteries for temperature control, too.

You could use the AGM batteries, especially if you have a non-vented area or might forget about maintenance,  otherwise a flooded lead acid is less expensive

  • Sat, Apr 11, 2020 - 09:37pm

    #4
    gujju420

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    Battery / Energy Backup for Solar Power Systems

are there any installers that you guys know in California, Bay Area that do a system for a reasonable price?

  • Sat, Apr 11, 2020 - 09:50pm

    #5
    gujju420

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    Battery / Energy Backup for Solar Power Systems

The new enphase coming out in June 2020:

https://enphase.com/sites/default/files/downloads/support/Encharge-3-DS-EN-US_1.pdf?fbclid=IwAR3kZkPJQvRMBaImeOjrify7XjVJ-gARtFGytaXr7Z7Ker7xWp7Bzyq_9ls

“a standard home battery option we install using solar edge and LG is about $12,500 before incentives or $6,750 after
that is for 10kWh which is about the minimum most people need for fridge and lights and phone/laptop charging for a day”.

Don’t forget to check out: https://www.cpuc.ca.gov/sgip/

  • Thu, Sep 16, 2021 - 12:36am

    #6
    Fred Pollard

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    Battery / Energy Backup for Solar Power Systems

Shawn, Great question “Energy backup for solar power systems” ??!!

For me I wanted an extremely easy long-term battery system that would last some 60+ years.  I have (4) 48 volt lead-acid forklift batteries that are configured to cycle up/down at 15% duty cycle.  You might ask “WHY” that is large, expensive and heavy. I just moved and still I have batteries in two different states as they are large and heavy.

What I discovered is many years ago, an old company warehouse had a 60 year old lead-acid battery servicing a lift.   Over the years the lift ran regularly with little use. When the company closed this site, the battery was so old folks were curious about how efficient that battery was.  The old battery was charged and load tested…. The discovery was that battery had only lost 30% of its ability to store energy.  I never had more then a article to read on this.

For years, I have asked many materials scientists about this idea of lead-acid batteries having extended life spans.   Chemists explained to me little is truly known about the electrolytic charge physics. However their is lots of data available on battery cell plate degradation.  Materials science folks can explain the sulfide processes and the chemists can delve into the passivation of plate surface area losses when lead acid batteries are heavily depleted and charged over and over.

What is interesting is their seems to be a sweet spot for lead-acid batteries when they are managed at 15% charge discharge rates. So my battery bank is made of large lead acid batteries.

Given used batteries have unknown charge histories, the next thing I discovered is a unique method of charging depleted lead-acid batteries using technology born from Thomas Bearden and John Badine.  These two smart people invented a spike battery charge system that pushes through traditional failed battery plates.  Lookup SSG charger (SSG stands for Simple School Girl science project, as I was told, John had this submitted for a school science project). The spike charge is able to charge dead batteries as the electrical spike penetrates the plate buildup.

I hope this information helps you and others. Now all I have to do is finish rebuilding my mini-grid in our rural location.

Electrical storage is based on 48VDC Excide forklift batteries, 4KW PV solar, some small wind turbine’s to assist. All feeding (1) 5kw Lamarche true sine wave inverter based on DIP discrete components (1990’s infinitely rebuildable). Also have charge controllers and other inverters, also added some phased 240VAC inverters (untested??? not sure if they work well) all this is backed up with a 15KW china diesel for short term needs.

For the most part this has been a hobby, however now I am 60 years young and may find this taking center stage with all the challenges taking place.

Remember, you should fit your solar system to what you need to run, consider managing your electrical loads so you don’t run short of battery life.  Electric hot water is nice, and I might recommend dumping unused electrical energy into a water tank, just don’t make that hot water your priority.  Modern refrigeration is a great luxury, just don’t expect your battery budget to keep that running long-term.

Consider your electrical loads carefully.   I met a guy that demonstrated how a chest freezer makes GREAT fridge. All he did is add a temperature control that turned the freezer on/off to maintain fridge temps.

BTW, used solar panels can be a great deal if you buy commercial panels.

Within the next 16 months, I should have my mess of alternative equipment (wife says heavy junk) re-installed and running.   Enjoy Life & Take care of all the people you love!

 

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