3/24/2022
I've long been aware that PV production raises nearby voltage. High voltage causes inverters to shutdown. I think the standard "give up" voltage is 260-265vac and may vary from one inverter to another.
I think typical Bluebonnet line voltages are about 245- 250vac. Even though "nominal" voltage is 240vac
A couple of months ago, a neighbor's PV inverters mostly shut down due to high line voltage. I think the utility, Bluebonnet, admitted that they raised his voltage to better serve other customers during a threatening weather event.
I recently discovered that I had two string inverters, serving up to 50 panels each, that were starting in the mornings but refusing to work mid day. So, I went out (after 3pm and after peak sun) and measured voltages. Here are the results:
House meter/transformer should be able to do about 37kw. Wiring goes from main breaker to sub breaker box on rear of house to breaker box that serves the south field where I was having the inverter problem:
1) main breaker box: 256-257vac
2) rear of house breaker box: 257-258vac
3) south field breaker box: 257-258vac
Total production is just over 20 kw and I wish to add two inverters that will produce about 7kw more. Those voltages tell me I probably have sufficient capacity to the south field breaker box. Significantly higher voltage on one end than the other indicates the wire is nearing maximum current capacity.
The new "hilltop" breaker box is taking only 25 amps, about 10kw. That is a 50kw transformer which should do about 125 amps. I have problems there that need to be corrected for better production. Line voltage was 251-252vac
The " across road" 50kw transformer is my best producer and was doing 122 amps.
1) main breaker box: 255vac
2) breaker box in "party shed": 261-262vac. That tells me that the wire from main breaker is fully loaded. So, I will not be trying to add additional capacity on that path.
3/25/2022 9am
All three breaker boxes chained to south field near house show line voltages of 250-252vac with PV production of about 10 amp. Full sun production from south field should be about 35 amps.
3/25/2022 3pm
This morning, I told our "renewable energy" Bluebonnet person, Brittany, of two problems: I have no 1099 from Bluebonnet reporting my income from 2021 and that I have the high line voltage problem. A Bluebonnet person came right out and reported ~252 at the meter and promised to "kick it upstairs". Their target voltage is less than 250, 247 or so. He reported that the source of my power is the installation near Bunton Cemetery and that he thought that there are no "regulators" between me and the power source. A "regulator" is a place where they can step line voltage up and down as needed. Brittany is of the opinion that Bluebonnet does not report amounts that they pay to customers for energy.
The visiting Bluebonnet guy seemed quite helpful but did not seem to fully understand "customer generation". He opened the meter housing so he could measure line voltage as far upstream as possible. He was holding a clamp on amp meter so I suggested he measure current at a couple of places including the not normally accessible meter housing. He measured 80 amp in my breaker box and 100 amps in the meter housing. I had not realized it but, apparently, my rooftop system does not go through my breaker box. He exclaimed "how are you using all that power?!". I had to inform him that that was power/energy I was delivering to the grid and not power Bluebonnet was delivering to me.
3/26/2022 7:30am
Line voltage: 246-247 before PV production
Even though I was not so informed, I imagine that my visiting Bluebonnet guy from yesterday reported the problem and something was done about it. The ~247 is "normal" while voltages the previous two days, 252 and 257 respectively, were very much abnormal. We are threatened by power outages that could result from heightened brush fire risks. I suspect Bluebonnet had upped my voltage in response to that threat.
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