I have posted on several other threads about my frustration with the 66 Hz problem and the fact that it essentially made the PW2 useless for battery backup as so many things in the house, including our dogs reacted badly.
This morning, I finally got the courage to do my first test power failure under firmware 1.37.0 and I was very pleased with the results.
I flipped the grid breaker with the SOC on my single PW2 at 44% and my two solar inverters (7 and 4 kW) putting out a total of 4.4 kW. I could see on the app that the solar went down immediately but when I got back to the house, the LED lights were not blinking, no UPSs were beeping, and the dogs were not barking. The frequency was 60.0 Hz. 5 minutes later both inverters were online again, powering the house and charging the PW2 at 60.0 Hz. This was major progress, as in past power failure trials, the PW2 would go immediately to 66 Hz and stay there long enough for me to get back to the house, lose patience, shut down the PW2 and start the generator.
As the solar output continued to increase, it fairly quickly got to the point where the PW2 was being asked to accept more than 5 kW. I was surprised how long it took 5.0 or even 5.1 kW without raising the frequency to more than 60.2 Hz, but I knew that eventually something had to give. Fortunately, my geothermal heat pump came on for a while and used ~ 5kW, but when it turned off, all solar went down as obviously as that point it was putting out more than the PW2 could handle. The SOC was 80%. I wasn’t sure what would happen next, but the 4 kW inverter came up successfully 5 minutes later and was able to power the house and continue charging the PW2. I could see my 7 kW inverter try and come on, but somehow the PW2 managed to keep that off while keeping the 4 kW going. Maybe it was pure luck, as I expected I would have to kill one inverter manually to keep the solar going, or charge the car, or cook something, but to have it self-regulate was almost too good to be true. I never saw any significant frequency variation from 60 Hz when I checked my Kill A Watt meter nor did the lights ever blink or UPSs ever beep during the whole test cycle.
In rural Northern and Central California, everyone here is worried about PG&E doing preemptive multiple day power failures when the fire danger is high, and I am counting on the combo of my solar and PW2 to handle most of the time without power. The fact the PW2 is now useful in those circumstances is very welcome. Now if I could just get the 2nd PW2, I might even be very happy.