This is what $15K in batteries looks like (for my solar panels)...

[FD1000]

Thank you for an interesting and educational thread, but...
Note to myself.
Never an RV, a boat, a second/rental house, a private pool, a timeshare....and based on this thread, never a solar system on batteries.
It's too much of a hassle.

 

[skyking1]

Thank you for an interesting and educational thread, but...
Note to myself.
Never an RV, a boat, a second/rental house, a private pool, a timeshare....and based on this thread, never a solar system on batteries.
It's too much of a hassle.

I am 100% grid, but my 16Kwh battery will keep the lights in and the food in the fridge from spoiling. That is all we care about. I have been through several outages in my life that were long enough to spoil a fridge ( 3+ days).
It is grid tied with net metering. The PUD stores my power for me.

 

[FD1000]

We have lived here for 25 years.
Every year we get outages, maybe twice per year for minutes. Every several years, we get one for several hours. 35 years in this country, only one time, we experienced 2 days with no electricity.
As usual, I use my analysis skills of risk/reward. It doesn't make sense to hassle with this.
If we had 10 times annually 7-8 hour outages, I would consider installing a generator for about $10K including the labor. Maybe 2 cheaper portable generators is a good choice. I never looked at this, so I'm not sure.

My grandson told me the best line ever last year. Grandpa, you are playing all day.
He is right. I go to the gym, hiking, and playing Bridge...and that's exactly how I like it.
No long-term projects, like restoring cars or building furniture/kitchens.
My specialty is to find great, cheap, honest contractors that own their own small business. I don't like big companies where I pay for overhead and a rookie fixes my stuff.

 

[Koolau]

surfFL and rmcelwee, have you factored extra home/property insurance costs into your calculations. FL has had (I understand) large increases in property insurance rates. I wonder how much extra insurance costs you incur from your respective set ups?

Thanks for your reports.

 

[rmcelwee]

surfFL and rmcelwee, have you factored extra home/property insurance costs into your calculations. FL has had (I understand) large increases in property insurance rates. I wonder how much extra insurance costs you incur from your respective set ups?

Thanks for your reports.

I asked my agent. She looked at me like I was crazy for thinking there was any difference. So, zero dollars. It doesn't make sense to me but I don't make the rules.

BTW, same thing on a swimming pool. She said no change.

 

[Koolau]

I asked my agent. She looked at me like I was crazy for thinking there was any difference. So, zero dollars. It doesn't make sense to me but I don't make the rules.

BTW, same thing on a swimming pool. She said no change.

Now that IS amazing. I hope she is correct and you don't find out that you're not covered when a casualty happens to occur. Best luck!

 

[skyking1]

I'll ask my agent too.

 

[surfFL]

surfFL and rmcelwee, have you factored extra home/property insurance costs into your calculations. FL has had (I understand) large increases in property insurance rates. I wonder how much extra insurance costs you incur from your respective set ups?

Thanks for your reports.

Hi Koolau,
Yes of course solution is insured, I've provided some details here (answering someone's question / statement)

Does solar payoff in a reasonable time, or at all?

I, too, have heard from people who report, "Solar is great! My electric bill was only $30 last month!" but who omit they also pay $300 per month to the installers. When the math is done correctly, it takes a high utility rate and/or good sunshine to make solar reasonably pay for itself. There...

www.early-retirement.org

Sorry it's a bit all over the place...

 

[Drifter]

My insurance actually went down $1100 in Florida.

 

[rmcelwee]

I have room for three more batteries in the racks. I will probably fill them because my OCD is getting to me.

Some things have changed in the past six weeks since I started the thread:
1) I sold my two old inverters and bought a second new type inverter.
2) I found a good deal on batteries and bought another three to fill the blank spaces in my racks.

The new equipment (minus the three additional batteries) is pictured. I'll charge the new batteries on the bench for a few days at a slow rate before adding them to the stack.

 

[Koolau]

Very impressive. How long can you have (sun-less) power with this set up (or have you tested it)?

 

[rmcelwee]

Very impressive. How long can you have (sun-less) power with this set up (or have you tested it)?

It is hard to test during sunny days. Winter is the big test. Over the past seven days, my batteries have been down to 62%-77%. The additional three batteries will add 20% capacity. If my math is correct (it probably isn't) that means I would have been down to 74%-92%. The range is mainly caused by DW running the oven/stove/microwave some nights. I really don't know what will happen this winter and I might not even get to find out. At some point I will break down the system and move it over to the new house. We will be back on the grid for a while.

All of that to say "I don't know".

 

[Koolau]

It is hard to test during sunny days. Winter is the big test. Over the past seven days, my batteries have been down to 62%-77%. The additional three batteries will add 20% capacity. If my math is correct (it probably isn't) that means I would have been down to 74%-92%. The range is mainly caused by DW running the oven/stove/microwave some nights. I really don't know what will happen this winter and I might not even get to find out. At some point I will break down the system and move it over to the new house. We will be back on the grid for a while.

All of that to say "I don't know".

Busy lately and haven't checked in much.

Thanks for answering. Please keep us posted this winter. Hoping for you to be able to stay off the grid (or feed it). All the best.

 

[surfFL]

Interesting hobby... I paid Tesla Energy to have a solar system + battery back-up installed. I have shared the financial, technical, motivation and real life timeline here:

Anybody have a power wall or other battery backup?

ECOFLOW offers a small dual fuel generator to connect to their ECOFLOW power stations that can auto-start when the power station's batteries run low. ECOFLOW is a bit pricy, but a very popular tried-&-true company. I use two Pecron Power Stations (E1500LFP) with three expansion batteries...

www.early-retirement.org

And ROI here:

Anybody have a power wall or other battery backup?

I was talking to my sister.... we both have a whole house generator.... she knows of a number of people who are getting quotes to get one.. However, someone she knows was told she does not have enough space for one (kinda surprised me as they do not take up that much space)... so, I suggested...

www.early-retirement.org

Just to recap 3 key points (from those 2 different posts):
a/ Timeframe: 19 weeks (or 4 months and 3 weeks) from $100 PO to Permission To Operate (PTO) on 5/13/2025
PTO is when you can claim the Federal Tax Credit, no PO
b/ Cost: $45k for 24x panels (9.84 kW) + 3x Powerwalls (PW) 3 (40.5 kWh)
c/ ROI: this is way I measured it. I've compared it to a whole house generator + buried LPG tank (I don't have natural gas here)
Summary "For me in 5 years I will break even, every year after Year 5, the Generator solution will cost me $2k more than the Solar Panels + Battery Backup."
Assuming I'll get the 30% Federal Tax Credit, which seems I should; since the BBB passed today calls for those credits expiring 12/31/2025 (for residential solar):

Congress and Trump End Popular Solar Tax Credit—Here’s What Homeowners Need to Know

Congress and President Trump just passed legislation to cut the 30% residential solar tax credit in 2026—nearly a decade ahead of schedule. For homeowners considering solar, act now to lock in savings.

www.energysage.com

Now that I have 1.5 month of experience with the system, I'm posting some data (complementary of NetZero App) for the month of June:

Summary:
View attachment 56882
==> I sold (Net Metering) 241 kWh to the grid (FPL), my June bill was $27... (solar subscription with FPL is $25/month w/o taxes). And they are crediting me $7 (for those kWH) in the June bill, so June bill is $20 in fact...

Solar production details:
View attachment 56883
==> The system outperformed the specs (PW Watts, the red dots on the chart above - note that NetZero does a weather adjustment of the PW Watts estimate; so that's as close a real life as it could be) by +12%

House / Car charging details:
View attachment 56884
==> I got 352 kWh 'free' for the EV, since I did not charge at any SuperCharger in 06/2025; that's 1430 miles (my EV is doing now 246 Wh per mile or 4.065 miles per kWh)

Additional experience
1/ The system was always online, except for 5mins (Teslas servers outage I guess) but it was working as normal during these times
2/ The system automatically updates itself (and NetZero sends a notification of the software update)
3/ Charge on Solar is available: I'm not using it though, I prefer lowering the Amp to 35A on the Tesla App - max is 48A (and thus wait a bit longer for the car to charge), but with 35A when the AC kicks in, I'm still not drawing anything from the Grid... Just the Powerwall (and solar if available) is charging the car.
4/ I've set up an Automation on NetZero App: If Powerwall reserve is lower than 35%, stop charging the car. This allows me to 'live' through the evening / night without drawing anything from the Grid
5/ I've got 3 grid outages during those 1.5 month, Tesla system kicked in automatically; I received notifications from Tesla App and NetZero App about the outage. There is a 1-2s voltage drop, so my 2 UPSs (Computer and Cable modem) are still useful
6/ The solution is adapting itself to weather conditions:
When it's sunny and though I'm consuming more kWh (with the house AC), the solar panels generates more energy
When it's cloudy, I'm consuming less kWh (with the house AC), the solar panels generates less energy
7/ The system if performing better than I expected on cloudy days (I was shouting for 15%), I'm closer to 30-40% which is fantastic. It only produces 0 kWh when it's raining.
8/ I've made my house energy efficient by adding:
- R30 insulation above the attached garage
- R8 insulation on the attached garage door
- Radiant barrier (aluminum foil) on the roof rafters
- Attic (smart) fan (hot air exhaust) to complement the soffits (cool) air intakes
This is also why 6/ is performing well, I think.
9/ The past few days we had very rainy / cloudy weather in Central Florida (complementary of TD3)
I've doing a 'hurricane test', can I live off grid? By changing nothing to my daily habits (including charging the EV) and see if the solution is self sustainable. It seems everything is performing above my expectations (I was expecting not to be able to use the water heater, range, MW and washer / dryer and charge the car in my initial sizing math)

So conclusion
A/ So far I've been living off the grid (including charging the EV) (I'm connected, but I generating more energy than I need) and the solution performs above my expectations / specs in various weather situations; but I think this needs to be put in perspective with having an energy efficient home (the walls are R13 and the attic is R30; the windows are impact, thus thicker and limiting energy leakage)
B/ If you are thinking of a solar system + battery backup solution, and if you are interested in getting the Federal Tax Credits, from my experience (time frame) and what I understand of the BBB; you should act now!

PS: As mentioned in the thread; I need to see if the solution will be able to be 'off the grid' in the cold months December/ January in Central Florida when days are short (less kWh produced) and I'm heating the house. That's the last challenge...

Success:
1/ Got 100% of my 2025 Federal Estimated Tax Payments refunded
2/ Carry Forward law on the FTC will allow me not to pay any Federal Taxes for the next several years (I filed the "Residential Clean Energy Credit" form in my 2025 return and it was accepted), until I can tap into my 401k (penalty-free) which is a perfect timing for me.
3/ Will end paying $31.5k for 24x panels (9.84 kW) + 3x Powerwalls 3 (40.5 kWh)
4/ As the house, car, power tools and gardening tools are 100% electric; I am 'Energy Independent', good thing to be those days
5/ Winter months test was also successful. I ended up importing 20kWh in January 2026. Since I've exported about 1MWh in 2025 (for about 1/2 year operation, since the solution was online in May 2025); FPL will owe me some dough in 2026... As we are in March, I'm already net positive for 2026.

I hope you guys took advantage of FTC as well.

Cheers,

SurfFL

 

[skyking1]

Success:
1/ Got 100% of my 2025 Federal Estimated Tax Payments refunded
2/ Carry Forward law on the FTC will allow me not to pay any Federal Taxes for the next several years (I filed the "Residential Clean Energy Credit" form in my 2025 return and it was accepted), until I can tap into my 401k (penalty-free) which is a perfect timing for me.
3/ Will end paying $31.5k for 24x panels (9.84 kW) + 3x Powerwalls 3 (40.5 kWh)
4/ As the house, car, power tools and gardening tools are 100% electric; I am 'Energy Independent', good thing to be those days
5/ Winter months test was also successful. I ended up importing 20kWh in January 2026. Since I've exported about 1MWh in 2025 (for about 1/2 year operation, since the solution was online in May 2025); FPL will owe me some dough in 2026... As we are in March, I'm already net positive for 2026.

I hope you guys took advantage of FTC as well.

Cheers,

SurfFL

I could not, as we are not occupying the house and did not get it approved and operating during the 2025 year. < heavy sigh>

 

[flyoverstate]

In some parts of the country, having that battery backup would be priceless. I'm jealous!

One of the reasons that batteries are so great is that you can store the energy you create and use it back directly without involving the power company in the transaction. We have very stable power from a non-profit co-op, and don't really need batteries, but that can change. The part of Colorado that is served by Xcel Energy *USED* to have stable power, but it is absolutely terrible now in many of their service areas. Mandatory blackouts due to high winds, random unexplained blackouts, and overall shoddy service end to end, from what used to be a really good utility called Public Service of Colorado, before it was bought out by Xcel, which sucks. Another example of why critical public infrastructure should not be owned by Wall Street, but I digress. Wait until your water system is owned by Wall Street and get back to me.

We are coming up on our first rollover date for our 10kw solar installation, the local co-op uses April 1 to April 1 to settle your net metering account. It looks like we will be in the neighborhood of 4000kwH of excess that we will be paid a pittance for, and I don't even know what they pay now, they have been changing the terms. I'm guessing around 4 cents/kWh, so we should get a $160 credit toward our $39 a month base charge. The base charge has gone up twice in the 18 months since we installed the panels. It started at $27, now up to $39, who knows what it will be next year. This constant rise throws off the payback calculus and is a complete wildcard.

At least we still have net metering here (many utilities have discontinued it), but I don't expect much excess going forward, since we will (probably) be getting an EV, and that will soak up the excess. I'm trying to hold out until a good V2H system appears, GM is close, but is ridiculously expensive and the reviews are not good. We have Enphase solar, and they have been promising their own V2H/V2G solution for years, but it has again been delayed. I'm beginning to think that it is vaporware. With the demise of the solar tax credits, I'm guessing their financials will be declining, and maybe it will be cancelled.

You obviously put a lot into that system and enjoy operating it. Good show!

 

[NW-Bound]

More batteries, more solar panels. That's my motto.

But wait, where the heck do I put them? Still have 13 panels waiting to be installed, plus 14kWh of LFP cells still sitting in the garage. My small solar shed has been choked full. Still have roof space, but installation of solar panels is tricky.

The existing solar shed is small, and I don't work that fast in the backyard remodeling project to have time for another shed. And the daily high is getting to 100+F already. Darn, my time is running out.

 

[NW-Bound]

My local utility has changed its rate structure. With so much solar power coming from residential installations as well as utility scale solar farms, they now charge as low as 3.95c/kWh during daylight hours, and as high as 40c/kWh around sunset. And cheap night time power for EV charging? Nope. Does anybody see the sun shining at night? The night power comes from nat gas, baby. You now pay 13c to 15c at night.

This rate structure more reflects the actual power generation cost, and I like it better. But the cheap power during daylight and expensive power at sunset gets me thinking. It now makes more sense to install battery storage than solar panels, particularly as the latter requires space. Let the utility generate all that power during the day from their solar farm, you just stuff it in your battery at 4c. Heh heh heh...

 

[NW-Bound]

A complication I run into is with so much equipment stuff in the small solar shed, it's hot in there when the ambient reaches 115F in mid-summer. I need to install an AC, but don't have room for that (the shed is way small). Been thinking about a mini-split intended for semi-truck cabs, like the following.

 

[NW-Bound]

By the way, the solar panels and LFP cells that I still have not installed were picked up more than a year ago, when I spotted some local good deals I could not pass up. I paid $600 for 14 used monocrystalline SunPower panels (I broke 1 by negligence), and $1000 for 14kWh of unused LFP cells still in factory boxes.

 

[ncbill]

Success:
1/ Got 100% of my 2025 Federal Estimated Tax Payments refunded
2/ Carry Forward law on the FTC will allow me not to pay any Federal Taxes for the next several years (I filed the "Residential Clean Energy Credit" form in my 2025 return and it was accepted), until I can tap into my 401k (penalty-free) which is a perfect timing for me.
3/ Will end paying $31.5k for 24x panels (9.84 kW) + 3x Powerwalls 3 (40.5 kWh)
4/ As the house, car, power tools and gardening tools are 100% electric; I am 'Energy Independent', good thing to be those days
5/ Winter months test was also successful. I ended up importing 20kWh in January 2026. Since I've exported about 1MWh in 2025 (for about 1/2 year operation, since the solution was online in May 2025); FPL will owe me some dough in 2026... As we are in March, I'm already net positive for 2026.

I hope you guys took advantage of FTC as well.

Cheers,

SurfFL

Hmmm...does my battery ("solar generator") qualify for the federal tax credit?

4 kWh capacity, feeding power to my gas furnace via this transfer switch.

The transfer switch is left set to 'generator' so the furnace runs exclusively off the solgen.

So the furnace never loses power in the event of a grid failure.

The solar generator itself is plugged into an outlet.

 

[rmcelwee]

We received our solar tax credit (refund) a few days ago. Two years of building the system and we are in it for $50,500 ($35,300 after credit). This winter was hard on the system as usual but even more so because we have part of our equipment at the Big House and were not able to fully utilize the solar/grid automatic switching. We spent a lot of time throwing the main breaker one way or the other to put the Little House back on the grid on the cold/dark days. We ended up spending $440 for grid over the past four months (we made around $1400 in PV). As of now, I think we would be 99.9% on solar power BUT we are getting ready to swap everything over to the Big House and that means more electric bills. I am a data junky and have yet to be able to log a full year of steady data on my spreadsheet. Constant upgrades and swapping things is ruining my attempt to find out how much we will "save" with the system. I have zero idea how much energy the Big House will actually use. Hopefully the PV will take care of a lot of it for the eight good months we get around here. FWIW, initial observations show that the house is fairly efficient. Once the 900,000 pounds of concrete came up to temp it is holding pretty steady. The contractors like to keep the doors open when it is snowing outside, but that is another issue. On the bright side, pun intended, the sunroom does a great job of heating the house in the winter. I think I will add a small propane heater to my office next winter and see how much that helps.

An interesting picture of two holes in my garage wall for the gas water heater (it was 25F outside), the hard lines from my HVAC under the drywall (but inside the concrete/foam envelope), my breaker box, my solar energy transfer switch. The little hot area in the lower left is a GFCI wall socket.