A few pages back I documented the problem I was having during an early morning power failure. Although there was minimal solar output, the PW2 frequency went to 65 Hz and stayied there for a long time even when the SOC was at only 60% SOC. Beeping UPSs and blinking LEDs were the symptom that was objectionable. We (this forum) attributed it to the fact that it was cold, 34° F, and the battery wanted to warm up before it would accept additional charge. That prompted me to call Tesla Support and have them lower the cutoff frequency to 62 Hz. Level 1 support would not connect me to Level 2 and insisted that my installer send them details about my inverters and they would deal with him, not me. I offered to send that material, but no, they had to hear from my installer before they would take this to Level 2 support.
A few weeks later, my installed called and said the Level 2 needed to know why I wanted the upper cutoff frequency lowered. What were the symptoms I was seeing? I was a bit dumbfounded as I thought that this problem was well understood, but I gave him the beeping, blinking and motors not running story and he relayed that to them. He called back a bit later and said that they would lower to 62.5 Hz, but not below.
Today I got around to testing the system starting in the morning with 49% SOC and the solar putting out about 5.5 kW which should be no problem for my 2 PW2s to accept. I threw the main breaker to the grid and was happy to see that both solar inverters remained on and the PW2 continued charging. The line frequency at that point was 59.7. The frequency slowly increased with the SOC and at 94% SOC the frequency was 60.2. At 96% SOC the frequency was at 60.4 and both inverters shut down. So far so good, but although the solar was shut down the frequency continued to increase until it reached 62.4 where it held. Unfortunately, at this point my LED lights were flashing. The UPSs were OK, but the LED lights (or their Insteon dimmers) were not. When the SOC dropped to 95% the frequency started falling, but it was not until 94% SOC and 60.8Hz that the lights stopped blinking.
Is there any point is asking my installer to ask Tesla to lower my frequency to 60.5 or 61 Hz? Will they do it? Or should I hope for a more intelligent frequency control in the future that either learns the inverters, or simply notices that there is no solar and no need for additional increases in frequency? Obviously given the posts above, I was not surprised the PW2 ignored the solar output, or lack of it, and raised the frequency to well above what was needed to shut down the inverters. The disappointment was that my LED lights were not OK with my new 62.5 Hz cutoff frequency.
