AndyH
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Sustainability of PV and Battery Storage

Tue Nov 10, 2015 1:33 pm

Interesting view of the sustainability of PV and storage from both lead-acid and lithium ion batteries. Examines manufacturing location and comments on Tesla's GigaFactory.

http://www.lowtechmagazine.com/2015/04/how-sustainable-is-pv-solar-power.html

http://www.lowtechmagazine.com/2015/05/sustainability-off-grid-solar-power.html
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GRA
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Re: Sustainability of PV and Battery Storage

Tue Nov 10, 2015 8:07 pm

Thanks, excellent articles.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

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RegGuheert
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Re: Sustainability of PV and Battery Storage

Wed Nov 11, 2015 3:27 am

Yes, good articles. Thanks for posting!

China certainly is doing major environmental damage to this planet and we continue to encourage it by sending all our manufacturing there.

I think they are stretching a bit to come to the conclusion that off-grid solar with Li-ion batteries is slightly more sustainable than current grid electricity (which, BTW, is not sustainable). They use the following assumption to get there:
Assuming a lifespan of 20 years for the solar PV system and a DoD of 80%, the lithium-ion batteries will last as long as the PV panels.

While I do think Li-ion batteries will eventually get there, they are not that reliable today. Tesla warrants their Powerwall for 10 years if you use it in float service, but only for 7 if you cycle it. The Enphase AC Batteries come closest, being warranted for 10 years with two very deep cycles each day. OTOH, no one really knows how long PV panels last. I have 2.88 kW of PV still in service after 16 years with no failures and almost zero loss of production. Simply put, PV could last 40, 50 or even more years. Li-ion batteries cycled 80% daily have no chance to last that long.

In other words, the authors assume Li-ion batteries last much longer than they actually do while simultaneously assuming PV modules die much quicker than they do.

At the end of the day, grid-tied PV in sunny regions is the most sustainable approach. Don't add batteries into the mix unless you're somewhere that grid-tie is no longer allowed or is actively discouraged.
RegGuheert
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WisJim
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Re: Sustainability of PV and Battery Storage

Tue Dec 15, 2015 11:33 am

We've been using battery based systems since 1977, first with a wind generator and then in 1981 we added our first PVs. We had used lead acid telephone company batteries at first and got 12 years out of one set before we moved and decided to junk the batteries rather than load them up and move them and reinstall them. The current battery (a set of 12 2 volt 1500 amp hour cells similar to fork lift truck cells) is now 16 years old and shows no significant degradation. The original PVs are doing fine with no loss of output that I can measure with 2 Fluke multi-meters. I am very interested in seeing how lithium ion batteries work out in the field as I hope to replace our lead acid set sometime in the future with something more efficient. PVs should have a 40 to 50 year life, at least twice the warranty period, and it would be nice to have a battery that was both efficient and long lived.

GRA
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Re: Sustainability of PV and Battery Storage

Tue Dec 15, 2015 6:02 pm

WisJim wrote:We've been using battery based systems since 1977, first with a wind generator and then in 1981 we added our first PVs. We had used lead acid telephone company batteries at first and got 12 years out of one set before we moved and decided to junk the batteries rather than load them up and move them and reinstall them. The current battery (a set of 12 2 volt 1500 amp hour cells similar to fork lift truck cells) is now 16 years old and shows no significant degradation. The original PVs are doing fine with no loss of output that I can measure with 2 Fluke multi-meters. I am very interested in seeing how lithium ion batteries work out in the field as I hope to replace our lead acid set sometime in the future with something more efficient. PVs should have a 40 to 50 year life, at least twice the warranty period, and it would be nice to have a battery that was both efficient and long lived.

Is your battery storage designed for an 80% daily DoD? Most off-grid systems aren't, and generally have three to seven days of storage. When well taken care of and only occasionally deep-cycled as is typical of residential use, Industrial lead-acids can last a long time, as can phone company stand-by batteries (those are usually lead-calcium float cells, which _need_ to be shallow-cycled).
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

WisJim
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Joined: Wed Jun 11, 2014 7:24 am
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Re: Sustainability of PV and Battery Storage

Wed Dec 30, 2015 5:57 pm

We've never discharged over 50% and did that only once or twice. Normally we discharge 20% max (using only 20% of the battery capacity). So we are only using about 300 amp hours of our battery on a regular basis.

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