Why even have batteries?

[h2ofun]

Got it. Several of our family members had farms and they also had tanks. I think mostly for heating.

I used to have large propane multipacks for heat, and still have a 400K BTU gas heater for my spa. But in the last year, everything has changed to electric other
than gas stove, gas water heater (which I have solar hot water panels for), and gas spa heater.

 

[Silicon Desert]

Interesting comments from folks. I see why it makes a lot of sense for some people to use batteries. For us up here, it didn't make any sense from an financial point and other reasons. We have a backup auto switching generator. For our home in Southern California, that might be a different story in the future if power reliability becomes a problem down there.

 

[h2ofun]

Interesting comments from folks. I see why it makes a lot of sense for some people to use batteries. For us up here, it didn't make any sense from an financial point and other reasons. We have a backup auto switching generator. For our home in Southern California, that might be a different story in the future if power reliability becomes a problem down there.

That was my intent of the thread so for folks to brainstorm why they do and what they do it. Thats how I get some good ideas to try different things.

 

[Silicon Desert]

That was my intent of the thread so for folks to brainstorm why they do and what they do it. Thats how I get some good ideas to try different things.

Yes, I thought that is your purpose of the thread, Good one. Informative postings.

 

[cali8484]

It seems this type of question often turn into a generator vs battery comparison. It's a false one to me. I see generator as a required component of a practical on-demand backup power solution even if you have batteries. Solar is not a reliable power source despite what the home battery peddlers say.
The simple fact is that batteries won't get charged enough on cloudy, smoky or just winter days. So, I see batteries as an add-on component in a practical on-demand backup power solution to minimize but not eliminate the use of generator in general.

Also, I think it's not very productive to try to justify home batteries strictly on financial ROI. I doubt most ROI focused solar owners would accept even a 10-year ROI for home batteries. It's just not the main factor used by people who buy home batteries so far. It's more about convenience and comfort which is why I am still considering home battery despite the lack of ROI. However, I really don't like the hassle of a major construction project and I don't like huge ugly looking boxes and conduits permanently attached to the house. Lately, I am starting to think perhaps a community (e.g. city/county level) battery-as-a-service option (if one exists) would be a better fit for people like me.

 

[GJones]

Solar can in fact be sufficient even in winter - it is a matter of sizing, location and prudent use when production is low. For myself, a 10kW system produces just over 40kW hours per day annualized (based on actual production data back to 2007). That means, I have a couple of days just over 70 kWHrs in the summer and a few days under 5 kWHrs in the winter. In the case of full off grid support of the house year round - I can do it, but only with battery backup - and for those winter days - they are generally interspersed with periods of sunshine that will allow full charge of the batteries. I could go off grid with extreme care with 2 batteries and 10 kW solar. I could easily do it without any concerns if I had 12 kW and 3 batteries.
YMMV.

 

[bevo]

We have all gas appliances. The only high demand items in our house are our AC and pool pump.

We have a battery for two reasons:

1. Backup power - We lose power often due to power shutdown during Red Flag conditions, equipment replacement/repairs, high demand on the grid, and equipment failure. Wanted to make sure we still have power when the grid is down
2. Load shifting. With the battery I was able to get the SCE Prime TOU plan. This plan lowers the off peak rate to $0.16/kWh and raises the peak rate to $0.41/kWh. With NET metering I can run the house off the battery during the high peak rate time and send excess solar to the grid, getting paid wholesale rates.

SCE Prime TOU is great for people with EV and no solar. Generally, if you have solar, you would be better off with the TOU 4-9 plan for 2 reasons.
1. The mandatory daily charge will add ~$10/month to the bill. This is on top of NBC. Your monthly bill is likely $18-$24. Monthly bill on TOU 4-9 is ~$13. This is assuming system was sized properly and generation exceeds consumption.
2. You actually want the off peak rate to be higher if you send more energy to the grid than consume during off peak. Again, if the system was sized properly, this is likely the case. Instead of getting $0.16/kWh credit, you'll get $0.27/kWh credit.

Do the math. I think you'll find you are better off without the Prime plan.

 

[holeydonut]

As I am reading threads on batteries lately, it hits me that many may not have really thought about, does one even really need, other than the cool factor.

First, for folks who have gas heating, the whole need of when and how to use electricity is TOTALLY different than folks who have electric heat!! When solar is poor in winter
and running gas heat, one does not even have to think about but my solar is only producing 5% of what is does in the summer. And now my ev2-a rate structure is killing me. Or I am not using that much with my battery, depending on what setting.

Then for folks who do not have a big difference between peak and non peak costs, why would anyone even have a battery? There is no chance for ROI. If it is cool for maybe a little power outage, great, we all decide how to spend our money. But ROI, no way.

It just seems that folks who have gotten a battery and are asking but how do I set it up, did not ask before they purchased, why are they buying and what are they trying to achieve?
Saying but I am greener to lose money, since the battery lose like 10% back and forth, makes not sense, IMO.

So again I just ask myself when folks ask about battery use and settings, seems the person first has to tell folks why they purchased the battery, and what needs or goals they have for buying it. And of course are the on net meeting, what is their rate structures, etc.

Just my engineering thoughts for the morning

I know that depending on how some of the changes happen with batteries, and reading folks questions, it is not 100% clear that batteries are something that it is going to be worth the hassle having. With solar, never had to think about anything. Batteries, its fun, but, ...

Some people aren’t blessed with monster ass houses where they can put on a metric crap ton of solar panels. I’m going to contend solar plus ESS is better than solar-only just because then the homeowner is less exposed to the crap the power companies pull. This is regardless what your winter heating fuel is.

The ROI of being mostly hedged against future electricity rate increases and policy changes is worth every penny of those cool-ass batteries. So if you get the batteries for free, that's great. If you pony up on batteries, that's great too.

I think people should be more upset with their power company, and they should strive for some form of independence from the utility. But Tesla doesn’t do a very good job of educating about the benefits of batteries. I wish the Time of Use thing was better advertised... although it is a confusing topic since the Power Company makes their rates so damn complicated. I’m glad people are asking questions here so they get the best bang for their battery buck.

PS, batteries are super cool too.

 

[h2ofun]

Solar can in fact be sufficient even in winter - it is a matter of sizing, location and prudent use when production is low. For myself, a 10kW system produces just over 40kW hours per day annualized (based on actual production data back to 2007). That means, I have a couple of days just over 70 kWHrs in the summer and a few days under 5 kWHrs in the winter. In the case of full off grid support of the house year round - I can do it, but only with battery backup - and for those winter days - they are generally interspersed with periods of sunshine that will allow full charge of the batteries. I could go off grid with extreme care with 2 batteries and 10 kW solar. I could easily do it without any concerns if I had 12 kW and 3 batteries.
YMMV.

I assume you have gas heating?

 

[sorka]

We have all gas appliances. The only high demand items in our house are our AC and pool pump.

We have a battery for two reasons:

1. Backup power - We lose power often due to power shutdown during Red Flag conditions, equipment replacement/repairs, high demand on the grid, and equipment failure. Wanted to make sure we still have power when the grid is down
2. Load shifting. With the battery I was able to get the SCE Prime TOU plan. This plan lowers the off peak rate to $0.16/kWh and raises the peak rate to $0.41/kWh. With NET metering I can run the house off the battery during the high peak rate time and send excess solar to the grid, getting paid wholesale rates.

This is the same for me. I have frequent power outages. Yes there is a cool factor when the power goes out at night and I decide to light up my floods just to show off when I'm the only house in the neighborhood that has powr

My AC is the biggest user by far. I bank power from march through middle of June and then have to fire up the AC. My 55 kwh that I produce on a clear summer day is leveraged into the equivalent of 78 kwh by selling peak back to the grid and using off from the grid while charging from solar. So my maximum savings with the powerwalls will com when I'm using AC for hours every day. Even then, I won't quite have enough with summer production to cover summer AC usage but I will when you factor in what I banked in the spring. I will again bank in fall after I'm not using AC to cover winter usage where solar doesn't quite but almost covers my usage.

In the end, if I'm not at least $120 net usage from the grid, then I'll lose any minimum billable below that, so it's not to my benefit to have 100% coverage but close to it.

In the summer when I'm using the AC, the batteries will net me 49 - 19 = 30 cents (round trip) that I send back to the grid during peak while using AC from batteries. Most days I'll use close to 35 kwh out of my 40 kwh during peak time from the batteries which will be 35 * 0.30 = $10.5 / day that I'm saving by load shifting or about $300 extra / month. Overall, I expect the 3 powerwalls to save an extra $1500 year round from load shifting. Those poweralls were $20500 (I got in before the price increases). Add sales tax and deduct 26% leaves total powerwall cost of $16535. The ROI ends up being about 11 years ASSUMING nothing goes wrong and that I don't lose an inverter for a month in the middle of the summer.

This compare to about 4 years on the solar alone if I didn't have powerwalls. The combined ROI for the entire purchase is about 6.2 years.

 

[sorka]

I think 5% is unusually low. My solar still produces about 25% in the winter of what it does in summer.

My January production was 738 kwh vs May which will be around 1700 kwh.

 

[sorka]

1. Oh, and for some folks, water.

All great points. For me this one especially since my water is a domestic well. I've been in the house for 20 years and once many summers ago we had a 2 day power outage and my acre of grass nearly died. I'm stubborn and maintain a perfect tall fescue lawn free of bermuda and other weeds. Most of my neighbors have given up and just have weeds + bermuda for their lawns. Fortunately I've got solid fencing and tall trees along the perimeter of the 1.3 acre boundary which seems to keep most of the toxic seeds out. I still have to treat about 100 square feet of infection / year. I mow my fescue to 5 inches and let it stay tall which also helps keep the weeds and other noxious undesirables out.

 

[sorka]

We know batteries, from posts here, lose like 10%. I do not believe if I send to PGE and use, I lose the same?

It's about the same when you factor in the NBCs.

 

[sorka]

Oh, and my ROI calculations assume PG&E won't raise their rates so it'll be even faster if they raise their rates which of course they will continue to do.

 

[SageBrush]

That was my intent of the thread so for folks to brainstorm why they do and what they do it. Thats how I get some good ideas to try different things.

What percentage of your retail PW cost is subsidized ?

This question is pertinent to everybody who installs home battery storage, but after reading some of your posts I'm having trouble escaping the notion that CA et al is paying to keep your sauna hot in the winter.

You are the second person I have read on this forum who makes me wonder how much the community is getting out of SGIP, Vs simply underwriting an energy guzzling lifestyle.

 

[SaveOurPlanet]

People get battery backup for different reasons for themselves and it is not anyone's business to tell people if they should or should not get battery backup. I get PWs because I want to be off grid as much as possible, I still use the grid in extreme situation when I cannot see the sun and I need to charge up the PWs to get me through the night until the sun comes up, if it comes up. Australia is talking about charging customers for exporting to the grid, I doubt it would happen here since this is America, right? Regardless, this is the similar argument people make why buy EV when the payback may not be there, especially any 90K plus EV. There are also arguments about cycling the battery due to degradation, but personally, I think I would have bigger problems if I cannot afford to replace my PWs in 10+ years due to degradation.

 

[Oceanwolf]

Living in the sticks means all of us have propane tanks.

We have the propane tank in the front yard at our cabin which became the main home during the pandemic. Other than the dryer we are all propane and no central AC. We have portable ACs for two rooms but since it is dry in the forest, the swamp cooler is magical. I don’t care about 2 powerwall’s ROI when I know PG&E will shut us down next Saturday and I don’t have to drag my generator to keep things going. By the way with 27Kwh I can forever in summer and at least 2 days in winter without any solar support. That beats any ROI thoughts in my mind.

 

[Electrph]

SCE Prime TOU is great for people with EV and no solar. Generally, if you have solar, you would be better off with the TOU 4-9 plan for 2 reasons.
1. The mandatory daily charge will add ~$10/month to the bill. This is on top of NBC. Your monthly bill is likely $18-$24. Monthly bill on TOU 4-9 is ~$13. This is assuming system was sized properly and generation exceeds consumption.
2. You actually want the off peak rate to be higher if you send more energy to the grid than consume during off peak. Again, if the system was sized properly, this is likely the case. Instead of getting $0.16/kWh credit, you'll get $0.27/kWh credit.

Do the math. I think you'll find you are better off without the Prime plan.

Glad to see someone came to same conclusion as myself regarding tou-prime when a net producer

 

[Laketime]

If you are discussing generators or battery backups then you have to separate convenience vs cost. This isn't a which stock/bond/CD will give me the best rate of return. A major reason a lot of people buy either or both is for backup which can be suffered through (cheapest option) or managed. The other major reason is for TOU arbitrage. That varies depending on where you live and your provider. We purchased for backup. When compared to a generator our 3 walls were roughly $4k cheaper ($12,500 vs $8600). Plus we don't have to spend $ each year maintaining. So far since install in December we have backed up 5 times. They were all minor and we would have certainly just pulled out the candles and been fine if we didn't have batteries. But we didn't have to because we had spent money on them. I'm on a Mercedes forum quite a bit- S class in particular. Every once in a while someone comes on trying to justify the cost. Of course luxury is not something you put to a value proposition. It's like so many things in life- you look at the scale and decide where on the scale you wish to be. Are you buying shoulder, porterhouse, ribeye, filet in choice, prime or waygu? You could buy chicken on sale and save a ton instead. It's one of the hardest conversations to get through my clients heads besides keeping a level head through headwinds (I'm a financial advisor). Deciding where on the scale various purchases and decisions should be...

 

[sorka]

2. You actually want the off peak rate to be higher if you send more energy to the grid than consume during off peak. Again, if the system was sized properly, this is likely the case. Instead of getting $0.16/kWh credit, you'll get $0.27/kWh credit.

Do the math. I think you'll find you are better off without the Prime plan.

I don't understand that this statement. I have 3 powerwalls and an 8.16 KW system. I'm on EV2-A. Are you saying I would be better off on a different rate? If so, which one?