Yea, the high peak rate is great for Power Wall people. It's still a big expense with a long (if ever) payback period. Can help Xcel a lot too. They should throw in a 1-2k rebate on a power wall install. That would be interesting.
So are you happy with your powerwall. How's it work during power outages? Can it charge when the grid is off? What Inverter do you have?
We've been almost 100% satisfied with our Powerwalls. We were lucky enough to earn them from the referral program so that helped our ROI a lot.
We did put in two solar systems back in 2018 and 2019. Due to COVID shutting things down, I've been working from home for nearly a year. That meant a lot less driving and we generated over 4000 kWh surplus in 2020. If I'd still been working in the office, we would've come closer to breaking even with production/consumption. The peak and part-peak credits helped so it was a bummer when we got the notice on 12/31/20 that they'd changed the ToU schedule for 2021 and greatly reduced the part-peak period.
Our Powerwalls have gotten us through several outages and normally they charge just fine during outages and let us keep everything in the house running, including being able to still charge our cars. Tesla released a software update last year to enable the cars to reduce or stop charging during grid outages so that they won't drain the Powerwalls. We did have a problem on a 48 hour outage back in early 2019. In brief, our Powerwalls got us through the first 24 hours without any problem but on the second day, the Powerwalls were drained down to 5% and shut off. They then got into a cycle where they would try to turn back on but then they would raise the frequency for the solar inverters, shutting things back off. Tesla modified some settings on our inverters and Powerwalls and we haven't run into that issue again. Later in 2019, we did an 8 day off-grid test without any issues, even with 8" of snow. In 2020, we had a derecho that knocked down nearly all the power poles in our neighborhood and the grid was down for 48 hours. Our Powerwalls and solar worked perfectly and we actually ran an extension cord to our neighbor's house to keep their refrigerator running.
Our two solar systems are 20.5 kW and we have four inverters:
2018 system: Delta Solivia 7.6 and 2 Delta Solivia 5.8 inverters (no shade on 4 arrays)
2019 system: Solaredge HD Wave 3800 (with optimizers)
While our solar panels only add up to 20.5 kW, you'll see that our inverters are oversized (so no clipping) and we've actually seen over 22 kW generation at peak production on some days.
We did have problems with Xcel last year where they were providing dirty power on our transformer (shared with 5 neighbors). This caused the Powerwalls to kick in and power the house over 860 times last summer, sometimes more than 36 times per day. While we never lost power, the Powerwalls frequently had to shut off solar production, causing our production to be 20% less on some days. After 6 months of complaining to Xcel, we finally got a new transformer installed and it is only shared with one neighbor. Hopefully this year we don't see
any 'outages' due to dirty power. On our best days last year, we produced 143 kWh. I'm hoping we can hit 150 kWh or even 160 kWh on our best days this year, assuming the grid stays up. We produced 98.5 kWh yesterday and
might hit 100 kWh today.