Tesla Solar/Powerwall for Tank/Home Backup (1 Viewer)

[foos]

Since the freeze I know a lot of us are looking for backup solutions and I already had my mind set on solar/battery so I got that, but did not see any forum posts directed to our hobby. I figured I would write something up and answer questions to help others decide between this and a generator. If you find this helpful, feel free to use my referral code.

Earn Free Supercharging Miles or a $100 Cash Award <- referal link

Amount of time it takes will vary, but this is how long it took for me:

3/16/2021
I ordered 12.24kW of solar and 3 Powerwalls

6/21/2021
First day of install, Powerwalls completed this day.

6/22/2021
Second day of install. All but a few cosmetic things finished.

7/10/2021
Centerpoint gives permission to turn on the solar system.


Costs change over time so you should check on their site to see what you are quoted but this ran me ~$50k and I got an APR of 4.99% with no early payment penalties. Bill will be $254.95/mo for 17 months, then if I do not do a bulk payment using my tax rebate it goes to $345.85/mo. Payment stays the same if I use the whole rebate. Terms said that 17 months is a one time recalculation period and that the remainder is calculated off what is still owed. So, if I pay more than the rebate my monthly would actually go down.


I'll edit and expand on this as I get an idea of what people want to know. I'm also going to reserve a few posts after this just in case I hit the limit of this.

 

[foos]

reserved 1

 

[foos]

reserved 2

 

[foos]

reserved 3

 

[foos]

reserved 4

 

[gregg]

How long is the note? And what’s your monthly electric bill expected to be reduced too?

 

[foos]

240 months

Year 1 production is estimated at 16015 kWh, my current rate calculates around 12 cents/kWh so it should offset around $160/mo of my bill. Considering I am on average billing at $178/mo..... I am waiting to hear back from reliant about the solar sellback program so should have real world numbers soon.

Assuming zero degradation of the system and electric rates never going up, if I paid the minimum and did not use the tax rebate for the bulk payment, it would take 42 years to break even. If I do the bulk payment it will take 32 years.

Yesterdays production:

 

[RobertP]

32 years for payoff? I assume the life of those batteries wont be even half that time. Are they warrantied to cover their loss and/or degradation? That is probably by biggest concern with it.

Does the unit still supply power to the house if the power is out? If so then it is a whole house generator in a way.

 

[foos]

32 year if you look solely at direct cost, and rates do not go up. After this winter our rates are guaranteed to go up, it is just a question of do we pay them directly in higher rates, or indirectly in taxes. If we pay in taxes, solar does not look as good.

If you do only solar it is closer to 15yr or less payoff usually, with a 20 yr warranty. The batteries have a 10yr warranty for I believe it was 70% usable capacity at that time.

Solar only, power goes out, you are in the dark. Solar+batteries, power goes out, you may not even notice. I did some tests and if the batteries are in standby and my a.c. is running when I flip off the main breaker, the a.c. compressor may stall if the timing is just right/wrong and one of my clocks may need resetting. That clock needs resetting if I sneeze too loud though..... If the battery is active and charging/discharging, not even the UPS's on my tank register anything.

Each battery has 13.5kWh when new and I have 3 so I have 40.5kWh. That means I can run 40.5 thousand watts for an hour. When my a.c. is running my house hits around 4kW, so the batteries could handle my a.c. tank, tv, everything I usually use for 10 hours. In reality my a.c. does not run non stop so I would get more than 10 hours, and the solar will add to that. My a.c. was a seer12 when new forever ago, and accounts for 3/4 of my usage. If I replaced that with a seer 30 I could double my run time. I also grew up in MN so I keep my place cold... From what I have seen for generation on cloudy days, if I got a single room portable a.c., I could run my tank and keep that room cool indefinitely.

So, the solar reduces your carbon footprint and saves you $$$ on electricity paying for itself and even making money over time. Batteries add whole house backup on top of that and make sure that you can still capitalize on your solar even if power companies decide to stop paying for your extra solar. I am not in the solar buy back program yet, so any solar I put out on the gird is free energy for the power companies, so I am running in self powered mode where the extra production is stored in the batteries, and used at night.

Basically, solar alone is almost guaranteed to pay for itself over time barring something catastrophic, power rates plummeting, or utilities deciding to not pay you for your extra you feed back. Solar+ a lot of batteries, probably never pay for itself, but works as a backup for your house/tank.

During the freeze I kept my tank running, fridge cool, and furnace heating on a 2kW generator. Looking at normal usage, I was probably using under 1kW on average while on the generator. If I had this solar and battery system then, it should have done the same for 40 hours with zero sun. With what I have seen on cloudy days and what I remember from the freeze, I should have had no worries.

 

[foos]

Got dark out and I heard rumbling and one of the UPS's on my tank went click-click. Checked, and power is out. All clocks set still and only one UPS registered anything.

 

[BigRick]

Got dark out and I heard rumbling and one of the UPS's on my tank went click-click. Checked, and power is out. All clocks set still and only one UPS registered anything.

Yup my power flickered. I like the instant energy of solar instead of having to wait a minute for the genny to fire up.

 

[R-BallJunkie]

man, wish i was younger..the paypack seems too long for me to entertain. I'm a Tesla fanboy (drive a MY).....do you think this could be done for less with off the shelf components, not going thru Tesla? For me, a good price point wold be 20K, not 50K . i think i asked this before....whats your total panel count?

 

[BigRick]

I dont plan on staying in my current home that long. Maybe keep for a rental but doubtful.

 

[BigRick]

Reserved 1 (For when I move)

 

[foos]

Yup my power flickered. I like the instant energy of solar instead of having to wait a minute for the genny to fire up.

That is one of my favorite parts. Only had this house a bit over a year and I have reset my clocks at least 50 freaking times. I swear every time the wind blows I get a flicker or 5 that are just long enough for everything to lose power and tank alarms to go off. Except this last flicker that is.

 

[foos]

man, wish i was younger..the paypack seems too long for me to entertain. I'm a Tesla fanboy (drive a MY).....do you think this could be done for less with off the shelf components, not going thru Tesla? For me, a good price point wold be 20K, not 50K . i think i asked this before....whats your total panel count?

36 panels.

I'm not a fan of the payback argument. It was started as pointing out a bonus, and people flipped it as not being worth it if it does not pay for itself. Not many things we buy ever pay for themselves. Maybe our houses, except when a bubble bursts, people end up upside down on the value of the house, lose it, and spend years trying to recover if they ever do. I think we should look at it and judge by the value it provides with the savings and maybe payback part of it, but not the main point. For me, I could afford and wanted a whole house backup. A system that allows me to go on like nothing happened for short outages and do minimal conservation for long outages. For the freeze, I woke up to tank alarms at 2am, decided it will probably be a long outage, and spent the next hour getting my generator set up before the UPS's ran out of juice. I then spent the next 3 days siphoning gas out of my car every 4 hours through an airline hose since that was all that would fit hoping that the power would come back before I ran out of gas. To me, the value of not going through that again make the system worth it even if it never pays for itself.

If what you really want is something that will back up your tank well enough to keep your livestock alive during an extended outage, you can definitely do that for a lot less. In that case I would look at adding a back porch roof like people tend to around here, but make it with solar panels and add a Victron inverter/charger and some Lithum Iron Phosphate batteries. Basically make yourself a beefy UPS with a long run time that can refill on solar. I'm not sure how you would automate that running on the solar to save you on electricity, but I'm sure it can be done. Something like this plus solar:

Battle Born Energy Off-Grid 24V 400Ah Kit

If you are living off the grid you need reliable power. Our new Off-Grid bundle is supercharged to help you get out there and stay out there!

battlebornbatteries.com

Now that I think of it, that setup could use the battery monitor relay to activate a mains relay. Make it so that you run off battery/solar unless the batteries get below what you set, then have it flip on the mains. I set up a system like this with less batteries and no solar yet in my mom's RV.

 

[foos]

I dont plan on staying in my current home that long. Maybe keep for a rental but doubtful.

Keep in mind the tax credit has only been extended for this and next year. In the past adding solar has been worth it as a selling point, but in this market.... Might want to ask a realtor if they think you could recoup the cost of solar when you sell your house.

 

[foos]

First week of solar on.


I also set up my home automation to adjust the thermostat if the grid is down and batteries are getting low to get me more run time.

I have the powerwalls set to self powered with 20% reserve, api gives real capacity including the bit that is needed to be reserved so the system can try and start solar with the grid down.

 

[Erin]

So, during the time where it seems no power is being used, how much electricity did you sell back to the grid?

 

[Erin]

Keep in mind the tax credit has only been extended for this and next year. In the past adding solar has been worth it as a selling point, but in this market.... Might want to ask a realtor if they think you could recoup the cost of solar when you sell your house.

A tax credit is only as good as the amount you owe... If you already get a refund, you won't see any additional money