One Year of Real Data From My Solar and PowerWall System

November 8, 2025 marks the one-year anniversary of my home solar panels being powered on. It’s been a while since I’ve posted about them, mostly because there hasn’t been much to report - so far, they just sort of work. But now that I have a full year of data I figured it was a good time to give an update, and hopefully answer the first question everybody seems to ask: was it worth it?

For background, for anyone who hasn’t read my previous posts, in summer 2024 I decided to get solar panels on my house. I chose Empower to do the installation. The installation was completed in October 2024 and I received PTO (permission to operate) on November 8th, 2024. My roof now has 36x 425 watt solar panels, and I have 2x Tesla PowerWall v3 battery units for local power storage, as well as a Tesla Gateway v3 to switch between the 3 power sources (battery, solar, and grid). My house is located on Long Island (in New York), I have LNG for heat/hot water (Navien tankless), a gas range, central air conditioning, and a Tesla Model Y.

I’ve been using my HomeAssistant instance to query the Tesla Fleet api for power metrics for basically the entire time, and the data is stored locally in my InfluxDB. There might be one or two days of missing data (at some point Tesla changed their API auth scheme and I didn’t realize it so I had to scramble to generate new API keys and update HA) but overall it’s a pretty complete record. I also have data from other sources like my Personal Weather Station in there as well.

Here’s a chart of the daily kWh generated by the whole array for the past year:

Here’s household load (how much we used) for the same period:

And here’s grid net for the same period - positive values are how much we used, negative are how much we sent back into the grid.

Here’s all 3 series charted together, but grouped by 30d instead of 1d:

For the whole year, my total load (usage) was 18644 kWh, my solar generation was 17122 kWh, and my net draw from the grid was 3407 kWh. I’m not sure why these numbers don’t really add up but I did have several months were I was using the PowerWall “arbitrage” function, where the batteries would fill themselves up to full during super off-peak hours (10pm) and then sell it all back into the grid during peak times (3pm). According to Tesla, this is recommended if your goal is to minimize your utility bill, and I think if I didn’t charge my car at night it might have made some sense. But ultimately I realized that the credits were being bucketed by PSE&G based on their time of day, so I was generating tons of credits during peak times, when nobody was home, and then using tons of electricity at night (to charge my car) and unable to use the credits for it. Around March or April I stopped doing that and went back to flat billing.

Was it worth it? Well, here’s my past 24 months of bills:

Of course, this is in addition to the NYSERDA loan which is $224.57/month for the next 14 years. As of my most recent bill I have 1,071 kWh banked, I guess we’ll see if that’s enough to ride out the winter. I’m kind of doubtful but only time will tell. Current balance on the bill looks like this:

I should also mention that the Storm Watch feature of the PowerWalls has kicked in several times over the past year, charging the batteries to 100% when a storm is forecast. We also had a few localized incidents where PSE&G was doing work in the area and notified us we’d be losing power during the day, so I manually scheduled a “Storm” for that day and our house never lost power, so this wasn’t a purely financial equation - we’re definitely getting added value from the solar+battery setup so far.

We’re only at the one-year mark but so far I’m pretty pleased with the system overall and definitely think we made the right decision getting it when we did. If I had to do it again I might have opted for 450W panels instead of 425W, but the price premium probably wasn’t worth the ~6% increase in production. If I ever get rid of my EV, current production will almost certainly be enough to carry me through a full year.

It’s a shame the federal tax credit for home solar was eliminated, as this seems like a major win for all parties. I really do think the future of the grid is batteries in every house to mitigate daily load peaks. As the technology becomes cheaper and cheaper it seems ever more obvious that this is the way of the future.

Thanks for reading, and I’ll check back in next year!