powerwall2 behavior when paired with solar

[Ampster]

I am sure there are some Californian households that have atypical electricity usage patterns that can justify the economics of a home battery system but I am talking about mainstream households. .......

I guess it depends on what you call mainstream. I think you are correct that the majority of Californians are not a market for battery backed solar systems.

I do think a market size of one million probably exists in California based on a back of the envelope calculation.
PG & E and SCE have a customer base of 30 million.
The median household income in California is $71,000
The CEC has a policy to have the IOUs adopt TOU rates in the next few years.
A market size of one million is clearly not mainstream but if I were selling battery backed hybrid inverter systems I would think it was a market worth looking at.

[Ampster]

Just because you don't know of the issues & problems of Li batteries, does not mean they are "maintenance free" or inherently safe.
..............

I agree it is important to know the issues and problems of LI batteries. Since there are a number of different Li chemistries it would have been more informative if the reporter had actually been more specific so we could all know which ones to avoid. The puzzling thing was the last paragraph which said, "Investigators are now trying to determine what kind of business the homeowner was running."
I do know Lipo batteries which are often used in RC helicopters are extremely volatile. I don't know if they are the ones that release hydroflouric acid fumes. Hydroflouric acid is nasty stuff. Some refineries use it in their process. A refinery explosion in Torrance almost released 25,000 pounds of that stuff near my former home.

EDIT: I followed up on the Fairfield battery fire and it turns out the guy was running an electric bicycle repair business out of his garage. He was charging a lot of batteries. I can only presume he did not have the right controls over temperature and/or voltage. The important issue to understand about Lithium batteries is they do not tolerate overcharging or charging at multiple C rates because they will overheat and combust. I would not recommend them to anyone who does not understand the different chemistries and the specifics of charging each of those chemistries.

Earlier I mentioned Lipo batteries because when they are used in RC helicopters or other RC hobbies the participants are often in a hurry to charge their toy fast and that is when the problems often occur. In fact, hobby stores sell fireproof bags that can be used to safely contain the fireworks when one of those Lipos go off.

[Ampster]

@SunEagle, you are correct, there is no right or wrong. These are just two different opinions. As I said earlier, it is nice we have choices.

[Mike90250]

But for some it is not as comfortable as a battery backup, which does not require you to think about buying fuel (if even available in an outage), does not emit any toxic fumes, does not require maintenance, can be relied upon to start and stop smoothly if you are away from home …

So no question that a gas powered generator is cheaper as a backup solution, but it does not offer the same level of comfort as a lithium battery does (especially if connected to solar).
And yes comfort is a relative thing that will vary based on each person and their specific situation

Just because you don't know of the issues & problems of Li batteries, does not mean they are "maintenance free" or inherently safe.

https://www.kcra.com/article/15-exposed-to-toxic-fumes-after-responding-to-fairfield-house-fire/27933317

FAIRFIELD, Calif. (KCRA) —
Fifteen first responders were treated for exposure to toxic fumes after helping battle a house fire over the weekend in Fairfield, officials said Tuesday.
The Fairfield Fire Department said 11 firefighters and four officers reported feeling sick after being exposed to the fumes.


Crews responded to a fire at a home on Ash Court around 5 p.m. Saturday. There, crews found 200 pounds of lithium-ion batteries in the garage, the Fairfield Police Department said. According to officials, the batteries emitted fluoride gas after being exposed to the fire. < mod note - actually Hydrofluoric acid fumes. >

That's when the 15 people were exposed to the toxic fumes.

The fire department also said the incident was so toxic that crews had to throw away all the hoses and boots that were exposed while battling the blaze.

[SunEagle]

In photos or in real life? Per miles driven there are more gasoline car explosions than EV fires. The press loves to show Teslas going up in flames. I have actually seen gasoline cars and trucks on the Interstate in flames.

Yep. And I had a friend that owned a Pinto. Yet they were lucky it didn't blow up when he had a fender bender.

Look it doesn't really matter what type of vehicle someone uses. They all have had a bad experience at one time or the other. Even planes fall out of the sky.

I just trust a propane gen set more then a Li battery system. It doesn't mean I am right or wrong. It means I don't trust batteries for any long term backup.

[Ampster]

LOL. And I have seen Tesla cars going up in flames so to each their own experiences

In photos or in real life? Per miles driven there are more gasoline car explosions than EV fires. The press loves to show Teslas going up in flames. I have actually seen gasoline cars and trucks on the Interstate in flames.

[SunEagle]

There you go. It all depends on one's experiences. The great thing is we all have choices. I don't worry about my Lithium batteries but I have survived a few surprises with propane that is heavier than air. I grew up with propane and our dog was almost asphyxiated from a propane leak in the kitchen of our home. I got rid of propane on my sail boat and went to compressed natural gas for safety. I have seen pictures of exploding propane tanks flying through the air.

LOL. And I have seen Tesla cars going up in flames so to each their own experiences

[Ampster]

I don't know. I would be less comfortable worrying about a battery that would drain and not provide me the power I needed every time then to have a 12kw generator that I can run for many hours and easily purchased bottled propane or connect it to my large RV propane tank.

There you go. It all depends on one's experiences. The great thing is we all have choices. I don't worry about my Lithium batteries but I have survived a few surprises with propane that is heavier than air. I grew up with propane and our dog was almost asphyxiated from a propane leak in the kitchen of our home. I got rid of propane on my sail boat and went to compressed natural gas for safety. I have seen pictures of exploding propane tanks flying through the air.

[scrambler]

As I said, comfort is a subjective thing that will depend on each individual personality and needs.
Nothing wrong with preferences either way

[SunEagle]

But for some it is not as comfortable as a battery backup, which does not require you to think about buying fuel (if even available in an outage), does not emit any toxic fumes, does not require maintenance, can be relied upon to start and stop smoothly if you are away from home …

So no question that a gas powered generator is cheaper as a backup solution, but it does not offer the same level of comfort as a lithium battery does (especially if connected to solar).
And yes comfort is a relative thing that will vary based on each person and their specific situation

I don't know. I would be less comfortable worrying about a battery that would drain and not provide me the power I needed every time then to have a 12kw generator that I can run for many hours and easily purchased bottled propane or connect it to my large RV propane tank.

[scrambler]

t an ICE generator is, at this time, more reliable and more cost effective, even if it is noisier.

But for some it is not as comfortable as a battery backup, which does not require you to think about buying fuel (if even available in an outage), does not emit any toxic fumes, does not require maintenance, can be relied upon to start and stop smoothly if you are away from home …

So no question that a gas powered generator is cheaper as a backup solution, but it does not offer the same level of comfort as a lithium battery does (especially if connected to solar).
And yes comfort is a relative thing that will vary based on each person and their specific situation

[J.P.M.]

Besides the environmental issue, installing solar is about saving money in the long run by using a free source of energy.

Installing a backup system is about buying comfort and security. You are spending money to have the luxury of having your own power when it is not available from the grid.

So the cost of a battery backup is not about ROI, but about how much you are willing to spend (or can afford) to get the comfort you seek.

That said batteries combined with solar, and with the ability to do grid balancing, do offer the ability to make some of your money back, even if not a lot, which is better than nothing.

The fuel is free, the equipment to turn it into electricity is not.

The present value of acquiring and operating a PV system might be equated to the present value of the avoided cost of future electricity purchases. If the analysis shows that PV costing more than the present value of future electricity purchases, then the PV is not cost effective with the assumptions and time frame used.

Part of the problem is and always will be getting and using assumptions about future conditions and things like utility rates, inflation, alternate investments, etc., as well as how long to make the analysis run.

It seems to me that at this time, batteries aren't cost effective for most users as a means to avoid peak rates.

Batteries do seem to have some use as a means of backup power in outages, but an ICE generator is, at this time, more reliable and more cost effective, even if it is noisier.

[scrambler]

Besides the environmental issue, installing solar is about saving money in the long run by using a free source of energy.

Installing a backup system is about buying comfort and security. You are spending money to have the luxury of having your own power when it is not available from the grid.

So the cost of a battery backup is not about ROI, but about how much you are willing to spend (or can afford) to get the comfort you seek.

That said batteries combined with solar, and with the ability to do grid balancing, do offer the ability to make some of your money back, even if not a lot, which is better than nothing.

[solardreamer]

It can be in California especially with TOU rates which are required under NEM 2.0. I have heard three cases where posters on this and two other forums have committed to a Tesla Powerwall based on the recent power shutoffs.. Those aren't necessarily economic justifications but probably emotional based on inconvenience and loss of frozen food.
During the past two years 2,000 SGIP incentives were rewarded which when coupled with ITC made the payback on those systems more economical.

I am sure there are some Californian households that have atypical electricity usage patterns that can justify the economics of a home battery system but I am talking about mainstream households. I see vendors offer plenty of home solar payback/savings calculators/tools but almost none for home battery. Typical home battery marketing I have seen talks mostly about non-economic factors. Home solar was around for a long time but significant mainstream adoption didn't happen until payback period was dramatically reduced. EV's followed similar trend. So, I wonder if and when home battery could be justified on economic factors for typical households. Or there is better alternative to home battery (e.g. microgrids, peaker plant replacement, v2g/v2h, etc.) to leverage battery for similar load shifting or resiliency benefits to mainstream households.

[Ampster]

Is there any place in the US where such system can be economically justified based on hard cost factors? It's certainly not in California with NEM but not sure about places without NEM.

It can be in California especially with TOU rates which are required under NEM 2.0. I have heard three cases where posters on this and two other forums have committed to a Tesla Powerwall based on the recent power shutoffs.. Those aren't necessarily economic justifications but probably emotional based on inconvenience and loss of frozen food.
During the past two years 2,000 SGIP incentives were rewarded which when coupled with ITC made the payback on those systems more economical.