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Sunday, January 21, 2024

Talkin 'Bout My Generation

I don't blog much about solar here compared to the EV content. Usually, our solar panels sit on the roof, quietly and ardently generating energy from sunshine. However, in 2023 a lot happened: we replaced our roof (that was complicated with solar panels up there); the virtual power plant (VPP) that our utility, PGE, runs had a big rule change. The VPP rule change meant that we had to contact Tesla to enable a new feature on our Powerwall systems. All of this seemed worthy of a 2023 review.

New Roof

The roof replacement has to be the first thing covered since this means the panels were off the roof for a good portion of the summer. We're north of the 45th parallel so the summer months are by far our most productive. So this downtime ate into the heart of our generation time.

Our roof replacement was scheduled for June 12th through June 14th. Roughly speaking, day 1 was old roof removal, day 2 was new roof installation, and day 3 was skylight installation and final cleanup.

With the scheduled removal & reinstallation (RnR) of the solar panels. We wanted to have the panels off the roof for as short a time as possible. We have two solar systems on our roof. A 4kW system from a local installer (Sunpath Services) and an 8kW system from Tesla (SolarCity).

May 26th

Tesla Solar panels removed

June 5th

SunPath Systems panels removed

June 12-14th

New roof installed

July 5th

SunPath Systems solar panels reinstalled. Panels were off for 31 days.

August 12th

Tesla solar panels reinstalled. Panels were off for 79 days.

The Tesla RnR took almost 3 times as long compared to Sunpath. With the Tesla PV system as the larger of the two and offline for all of June, all of July, and half of August, we missed the bulk of the solar production for the year.

The good news is that we installed a 50-year roof, so that shouldn't be a problem ever again for these panels.

Side note, we were picking nails and other things out of our lawn and shrubs for days after this roof work, even after they magnet swept multiple times.

Virtual Power Plant

We signed up for our electric utility's VPP in 2021. To be eligible, you had to have home batteries, such as the Tesla Powerwall. When the program started, the utility paid you $20 every month. In return, your battery is available when they call on it to supply energy to the grid; you could opt out of the VPP events.

In June of 2023, the rules changed. Under the new rules, rather than just getting paid for enrollment, you now get paid for participation. The program pays $1.70 per kWh that you export to the grid during a VPP event and you can select the level of participation (up to 80% of your capacity).

With our 3 Powerwalls we have about 40 kWh of storage, so that's about 32 kWh that we could export. A full 80% participation would be $54 earned per event.

We had a total of 12 VPP dispatch events in 2023. As you might expect, most were in the summer (7 events in June - Sept). The other 5 were in January, February, and December. This surprised me. You expect the grid to be strained during the summer months with the AC units on high and dispatching the VPP seems like a smart way to avoid turning on the peaker plants. Maybe these events are in response to outages or maybe these events are testing new VPP controls.

VPP Incentive Payments

January - May we received the standard $20 per month credit. In June the new program started there was a quick 1kWh test. We received a $1.70 credit. In July, there were two small events and we received $32 in credit. August had a small event and we received $9. Our September bill had multiple events and received a credit of $157. This was a big credit and paid our next couple of electricity bills.

In total for 2023, we received a total of $325 in credits from our utility.

We Stopped Exporting

There were two dispatch events in December of 2023 and our system didn't participate. I emailed PGE and asked them if they knew why my system was not exporting. They said there have been multiple software changes to both their system and the Tesla systems. Now to participate, I had to enable Powerwall exporting in the Tesla app. They sent simple instructions to go into the Powerwall settings and enable export "Everything."

Going into the app, I didn't see any export setting. I double-checked the instructions. I was in the right place, but the setting was not there. Another email to PGE. They said Tesla had to enable this and then it would appear in the app. So I called Tesla Energy. Happily, I was not on hold for very long and the person who answered the phone (Justin) understood what I was asking for and was able to resolve it. He said to wait one hour and the setting should be there, if not reboot my phone and check again. Of course, I could not wait an entire hour before looking. The setting appeared in about 10 minutes and I enabled it.

Side Effects

Once this feature was enabled, the next morning when we hit peak time (6AM-10AM), our Powerwall exported all of its energy down to the Backup Reserve limit. That was not the behavior I expected. By going into the TOU settings and tweaking sell prices, I was able to leave this setting enabled (to participate in VPP events), but not have it completely drain the battery during every peak time.

Now we had Export Everything enabled and good daily battery behavior. We're ready for the next VPP event.


In 2023, there were several times our Powerwalls kept our house running when the grid failed. The longest outage was for 3 hours on August 7th.

Solar Year In Review

Above I explained how we had all of the panels off our home for most of the summer for a roof replacement. That put a big dent in our production. The older 4kW panels produced 3,246 kWh and the Tesla 8kW panels produced 5,113 kWh, for a total of 8,359 kWh. For comparison, in 2022 we generated over 20,000 kWh. So in 2023, we generated less than half of our typical production level just by missing 80 key days.


Throughout 2023, we sent 1,937 kWh of energy into the grid. A large refrigerator uses about 1,575 kWh annually. So we exported enough energy to run our neighbor's fridge for a year with enough left over to power their EV for about 1,000 miles.

Wrapping Up

2023 was an action-packed year for our home energy systems. For 2024, we should go back to our full production level. And 2024 will be our first full year under the new VPP rules. Earning another $300 or more in credit would be nice.

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