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PowerWall...Why?

Lex444

Member
Sep 26, 2019
44
23
New York
Curious about PowerWall, but dont really see the advantages. I live in NY, do not have solar, and do not believe my electric provider alters rates for electricity during different times of the day. What is the advantage of getting a PowerWall? What are the advantages over a generator? Thanks to anyone who responds.
 

ItsNotAboutTheMoney

Well-Known Member
Jul 12, 2012
10,880
8,579
Maine
Curious about PowerWall, but dont really see the advantages. I live in NY, do not have solar

There can be value for people with solar: self-consumption if better than selling/giving it away to the grid.

, and do not believe my electric provider alters rates for electricity during different times of the day.

Did you check?

There can be advantages for people in areas where TOU is available without significant cost or restriction. Definitely available in California and in Maine.

What is the advantage of getting a PowerWall? What are the advantages over a generator? Thanks to anyone who responds.

Advantages compared to a generator:
- Allows for self-consumption of generated solar. (Increasingly abusive utilities and hostile politicians are pushing to eliminate net metering)
- Zero maintenance. (It can certainty fail, of course).
- No dependency on fuel supply/delivery during an outage. (Obviously you'd need solar+battery, and sunshine)
- No local emissions. (Can be inside your house, without venting.)
- May recover some cost through TOU pricing. (Depending on availability and rules).
 

Chopr147

Active Member
Apr 3, 2016
1,940
1,470
Wantagh, NY
I live on Long Island and looked into the Powerwall. I have solar but it's just not worth it to me. It would have cost me over $10k. I pay a total maybe $400 a year in electric. 14+ years to break even? No thanks. PSE&G does not lower rates for time of day. Sandy knocked our power out for 9 days. Since then? Not once. I'll use the generator
 

JayClark

Member
Aug 6, 2019
226
189
Arizona
It usually only makes sense financially if your utility has rate plans that make "off-peak" rates very cheap, but where "Peak" rates are very high, and/or where Peak periods also have demand charges - and finally where peak rates occur when Solar mostly doesn't produce. Otherwise, some may value having strong and reliable full house backup, regardless of costs.

I live in Arizona, and my utility has off-peaks rates as low as 3.6 cents per kWh, and the PWs give me the ability to eliminate "Peak" usage and eliminate high "Demand" charges completely (i.e. zero home power draw from 2-8pm in summer by running on the PWs) which allows me to cut nearly $3000/per year from my pre-solar/PW electric bill.

In my case, I moved to an electric car also, and that saved me another $2500/year in what I was paying in gas commuting to work, by charging the electric car completely during off-peak at 3.6 cents per KWs. So For instance I can drive 35-40 miles on about $0.25 of electricity at off-peak rates, vs $4-8 per 35-40 miles in my small gas car (depending on the gas car, and price of gas per gallon).

So at a total of $5500-6000 in savings per year, the system pays off in about 7-8 years in my case, but that's before considering any added home equity at the time of home sale. A purchased ~$45,000 Solar/PW system (not leased or rented!!), depending on the real estate market, should add at least 15-20k in home value at the time of sale, in which case the pay-back period at point of sale is more like 3-4 years. And to be clear (I'm married to a Realtor) a leased or rented solar system actually "decreases" the value of your home at the point of sale since it's an obligation the buyer has to be willing to "take-on" and pay for (both in terms of the lease, and the Utility companies rate plans) that can only be eliminated by paying off the system or paying to remove the system - seen it many times. Not a problem with purchased systems.

Either way, after the payback period that's $5500+ in savings per year that I would otherwise spend to power my home and put gas in my old car... but in my case all of this only works if I can get through my utilities expensive "8 hour peak" that occurs each day when solar is mostly not producing without using any power, in order to take advantage of extremely low off-peak rates for all other usage. This is only possible with multiple PWs in my case, but I only need a small solar system to pair with the PWs. And in the winter I'd only need maybe 1 PW, but summer in Arizona requires more like 2-3 PW for my house, but I have 4... just because.

The other reason is for backup - which really is a minor consideration in my case - but it's nice to know the whole house will run during most of the year from only the PW (no grid) if needed for several days if I'm careful with my usage.
 
Last edited:

Lex444

Member
Sep 26, 2019
44
23
New York
Appreciate all the replies. Sounds like it is not for me. I did check now and my utility company does not offer off-peak discounts. Also not having solar makes this even less enticing. Thank you for the info.
 

bob_p

Active Member
Apr 5, 2012
3,725
2,922
We just completed evaluation of our options for solar and/or PowerWalls.

One of the options we considered was to install only PowerWalls and use them for backup power (quiet compared to a gas generator) and to lower electricity costs by taking advantage of free or lower priced nights/weekends. We concluded this option doesn't make much sense:
  • PowerWalls will cost 30% more when installed without solar, because the federal 30% tax credit only applies to PowerWalls when installed with solar
  • PowerWalls have a 10 year warranty when used with solar; but a much shorter warranty when a PowerWall is used with solar, because the PowerWalls in that mode will likely have more charge cycles
We decided to go with 15 KW of solar and 4 PowerWalls. We'll qualify for the 30% tax credit on the entire installation. The PowerWalls will be used to store solar energy for use when the panels aren't generating power. For short (1-2 hour) unplanned power outages, the PowerWalls will provide backup power to the house. For longer anticipated power outages (hurricanes), we'll have the PowerWalls fully charged to allow us to operate off grid for days, if needed. And, we may be able to use them to take advantage of time-of-use plans by using the grid for power when the rates are low or free - and have the PowerWalls provide power to augment the solar panels the rest of the time.

When backup power isn't a goal - and the local grid supports 'buyback' of excess solar power, PowerWalls aren't needed. But without them, you are reliant on the grid for power for much of the day.
 
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nyprepper

Member
Nov 8, 2018
126
152
NE US
Curious about PowerWall, but dont really see the advantages. I live in NY, do not have solar, and do not believe my electric provider alters rates for electricity during different times of the day. What is the advantage of getting a PowerWall? What are the advantages over a generator? Thanks to anyone who responds.

I'm in NY. I went with solar and 2 powerwalls last year for backup power in the event of grid outages. with the federal and state tax credits on storage it was very attractive relative to an LP whole house backup generator. After tax credit, my powerwalls added an incremental $9k cost of the system. I lose power fairly frequently. With my 6.6kw array, assuming very modest solar production, and running only essentials in the house, I can run off-grid pretty much indefinitely in theory. I could not be happier. We have had several 4+ hour outages recently and I definitely don't miss going outside to start the portable gasoline generator during a storm. I keep the Powerwalls set at reserve only. Even so, my first year I saved around $2500 on my annual utility bills over the prior year without solar.
 

gpez

Member
Apr 25, 2019
735
602
USA
I'm in NY. I went with solar and 2 powerwalls last year for backup power in the event of grid outages. with the federal and state tax credits on storage it was very attractive relative to an LP whole house backup generator. After tax credit, my powerwalls added an incremental $9k cost of the system. I lose power fairly frequently. With my 6.6kw array, assuming very modest solar production, and running only essentials in the house, I can run off-grid pretty much indefinitely in theory. I could not be happier. We have had several 4+ hour outages recently and I definitely don't miss going outside to start the portable gasoline generator during a storm. I keep the Powerwalls set at reserve only. Even so, my first year I saved around $2500 on my annual utility bills over the prior year without solar.

Exactly this for me. We get occasional, short wind/snow related outages here in the pacific northwest and of course there is the threat of an earthquake. I looked at getting a small portable generator, a home standby generator, and solar+Powerwall. You can guess which one won out! Portable generator was not attractive as it would need long extension cords, is a pain to set up, requires regular maintenance, and has messy fuel unless you go with propane. My yard equipment is all battery powered and I have a built in natural gas grill so I'd have to keep separate fuel for a generator. The standby generator seemed like a good option on paper but after I looked in to it I found out they're noisy, still require substantial maintenance, and won't work if the gas supply is shut off after an earthquake. Plus the quotes I got were crazy expensive between the equipment, delivery, installation, upgraded natural gas meter, gas piping, electrical panel updates, automatic transfer switch, and a yearly maintenance plan. The solar+Powerwall has literally 0 maintenance, can ride us through short outages without really worrying, and would still function even after a substantial earthquake. There is still the chance that a strong winter storm could knock us out for more than a few days and prevent any meaningful solar production. For this I have an inverter kit for my Chevy Volt that, in theory, could power critical parts of the house for about a week on a tank of gas.

Full net metering + production incentives + federal tax credit means my solar will pay off in less than 10 years, adding the Powerwall was about 40% cheaper than a fully installed home standby generator. On top of that the peace of mind knowing that we'll have reliable and fuss-free power during an emergency for my young family is priceless.

(Added bonus: I have networked my Powerwall to my home automation system so that the house can start to shut things down automatically during an outage!)
 
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astrorob

stealth performance M3
Aug 27, 2014
487
116
oakland, ca
  • PowerWalls will cost 30% more when installed without solar, because the federal 30% tax credit only applies to PowerWalls when installed with solar.
just so it's clear, you would get the 30% (or 26% next year) ITC if you install powerwalls against *existing* solar as well.
 

GenSao

Member
Aug 3, 2017
565
966
Pleasant Hill, CA
just so it's clear, you would get the 30% (or 26% next year) ITC if you install powerwalls against *existing* solar as well.

Per the Tesla Powerwall FAQ with emphasis in bold:

Federal Investment Tax Credit (ITC)
Powerwall is designed to qualify for the Federal Investment Tax Credit (ITC) when it is installed on an existing or new solar system and is charged 100% with solar energy. It does not qualify when installed without solar or if solar is installed after Powerwall. You should always consult your tax professional for your situation.
 
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Dan123

Member
Jun 19, 2018
451
321
Miami
Curious about PowerWall, but dont really see the advantages. I live in NY, do not have solar, and do not believe my electric provider alters rates for electricity during different times of the day. What is the advantage of getting a PowerWall? What are the advantages over a generator? Thanks to anyone who responds.

Without solar, it is not worth it. With solar, it turns your system into an automatic emergency backup generator, which usually cost $15,000 installed.
 

bob_p

Active Member
Apr 5, 2012
3,725
2,922
When projecting our break even point on the solar/PW investment, we excluded around $10K of the system cost - about what we would likely spend to purchase a gas generator, since we plan to use the solar/PW system not only to reduce our long term energy costs but also to provide backup power during short term or multi-day outages.

Having backup power provides some benefit - and if a gas generator is installed - it would be a net cost - since it would never generate any energy savings - so it's reasonable to remove some of the PW cost to recognize the value of having backup power.
 

Shadious

Member
Jan 11, 2018
381
247
Florida
We went back and forth on the powerwalls. In the end I decided it wasn’t worth the cost, even in Florida where we get hurricane scares annually. However, as luck would lad have it, I was able to score a good deal on 2 referral powerwalls and took the plunge. I probably saved a couple thousand over buying direct from Tesla and saved at least $5k over the cost the solar company was going to charge. Are they with the cost- to me it was only because we got a really good deal.

the one thing to consider in Florida is that in the event of a power outage. You cannot use solar panels to power the home, UNLESS you have battery backup. It keeps the linemen safe. I would be so annoyed to have all that power being produced after a storm and no way to harness it !
 

nyprepper

Member
Nov 8, 2018
126
152
NE US
When projecting our break even point on the solar/PW investment, we excluded around $10K of the system cost - about what we would likely spend to purchase a gas generator, since we plan to use the solar/PW system not only to reduce our long term energy costs but also to provide backup power during short term or multi-day outages.

Having backup power provides some benefit - and if a gas generator is installed - it would be a net cost - since it would never generate any energy savings - so it's reasonable to remove some of the PW cost to recognize the value of having backup power.

Agreed. The other variable to consider is the efficiency of a gas generator and the cost of fuel to run it. For me it would need to be LP....and LP generators burn crazy fuel..... like a propane Dodge Viper. I wouldn't be comfortable with less than a 1000g tank. I did the math at one point and the cost of fuel i'd likely burn over the course of a year during grid outages made the PW/Solar option a no-brainer.
 

rjdunn

Member
Jul 7, 2018
35
30
Emerald Isle, NC
I’ll echo much of what’s been said, that it’s the backup capability and self consumption ability that make it worthwhile to me. My utility does not offer net metering, and is a “Buy-all/Sell-all” so solar is really uneconomical. The Powerwall (I have a single PW) makes it possible for me to use most of my solar.

Realistically my payback is 30 years. But I installed my system since it’s the right thing to do, environmentally, and financially I was able to do this.

I started with a modest array, 4.35 kW, since I can’t be a net exporter to my utility’s grid, even if I don’t want compensation. With this, I still generate 50% or more of the power my house uses (including charging my Chevy Bolt). During shoulder seasons (no heating or cooling), I have to juggle car charging and other loads to avoid export if the Powerwall fills up. I can use more power in heating and cooling seasons, so I’m adding another 1.74kW on a separate string to the inverter. The installer will have a switch between these panels and the inverter so I’ll turn them off when I can’t use the power. Not a perfect solution but it works.

However, having the Powerwall does allow you to operate in a grid outage, as has already been mentioned. We had a short (less than 1 day) outage during Hurricane Dorian this fall where the PW ran the house, and appropriately turned the panels off when it was approaching full, and then turned them back on again. It’s nice to know this capability exists. I do also have a portable propane-fueled generator but I’d rather use sunshine for backup power!
 

Lloyd

Well-Known Member
Supporting Member
Jan 12, 2011
6,334
2,200
San Luis Obispo, CA
I live in California and peak at .56/Kwh vs .16 off makes it worthwhile in addition to the backup. I have a 6 year payback with the rate savings alone, not to mention the backup benefit. Powerwall and solar provide 100% of my usage during peak periods on most days.
 

S4WRXTTCS

Well-Known Member
May 3, 2015
5,711
6,847
Snohomish, WA
For myself it would simply save me the inconvenience when the power goes out. It's a bit weird because a few years back I hardly ever lost power, and now days I'm lucky to go a month without a short power outage to the entire area around me.

Now if I lived in California with rolling blackouts I absolutely would get a power wall. They're probably selling like hot cakes in California right now.
 

bob_p

Active Member
Apr 5, 2012
3,725
2,922
When estimating our break even, another factor was the projected cost of electricity we would still be pulling from the grid.

We opted for a system that will provide about 50% of our total power usage (including EV charging).

In our break even estimates, we included the savings from electricity generated by solar (and saved in PW), excluded $10K for the value of backup power, plus factored in the lower cost of the electricity we would be pulling from the grid.

Since electric rates (at least in our area) are lower per KWh when using smaller amounts of electricity, we could see a 30-40% reduction in per KWh charges for the electricity we'll still be pulling from the grid.

Excluding the PowerWalls would have reduced our overall system cost considerably - but we didn't want to be reliant on the grid or on the few utilities that currently have solar buyback plans (since buyback is not required in TX).
 

Ulmo

Active Member
Jan 19, 2016
4,329
4,905
Vienna Woods, Aptos, California
Why:

Get new high efficiency heat pumps, heat pump water heater(s), electric stove range and oven, electric dryer, 4 PowerWalls + 15kW solar (25kW solar or more if you have a medium electric car commute, 45kW solar or more if your spouse also has a medium electric car commute), and a frequency slave-synchronizing manual start diesel backup generator for extended storms and extended power outages, and then disconnect your utility. Have them take the electric meter and gas meter out, and cap the gas at the property line so it doesn't leak (have a good plumber or the utility do that). If they won't let you disconnect, then find out what kind of plan you can get with the least bill (maybe electric-only, gas-only, whatever; maybe get a senior on a low cost plan to keep the monthly bill down), and disconnect everything.

You will own your own energy. No one else controls your energy. Go as far as you like. Heat your home up as much as you want.

If you live in a place that doesn't need humidity to prevent fires, then add even more solar, a treated potable water tank, and an optimized water condenser (optimized to produce as much water as possible), which will collect enough water from the air for you to drink and have some showers. This will reduce your water usage, and if you use graywater treatment and filtering from your shower and laundry, you can use that to water your lawn. That will get you in the door of hedging water utility dependence; if they start to over-charge, you can increase your solar and water condenser collection.

That would leave you with only garbage and sewer collection bills. I don't see a way around those in a modern society.

I can't say any of this has near term financial benefits. But it will remove your dependence on most utilities, practically every utility that doesn't deal with waste. If you have a lot of land, you can farm grass, animals, and if you want, vegetables. You might even have septic in a rural area. Then all you'd need are roads, firemen, hospital, doctors, ambulance, and sheriff, and you can make friends with them, and also you would still need the refuse dump service.

It's about owning your own destiny.

I don't think it's optimal, but take from it what you will. See if you want any of that independence, and you have it available to you. There are all sorts of opportunities here: you can build and live in places that have no utilities and still have all modern facilities at a reasonable cost, even though that was not possible before. Note that communist laws have probably tried to remove those areas from legal development, but all you have to do is pay them a couple hundred thousand in permit fees, and if you're doing that, you might as well leverage your independence in some way to make even more money. You have to be pretty creative to do all that. But I'm talking about ideas, so take from it what you will.

That's today.

In a decade, some of that will trickle down-market.

In 50 years, a lot of that will trickle down-market.
 
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