posted 3 days ago
Dear Fellows,
I've run into a strange solar panel problem, I would like to pick your brains to hopefully figure out what could be going wrong.
First my setup: due to east-west facing of our home, we installed 6 solar panels on the east part of the roof and 6 on the west. 6 panels on each side (let's call this a set) are serially connected to each other. The two sets are connected in parallel. The panels are approximately 500 W each. I bought the west facing ones a few years earlier, but they are not older than 5 years old. We do have a 6.8 kW inverter and 5kWh lithuim-ion battery. The system was working when I last saw it.
When I arrived our off-grid home a couple of days ago, I noticed that the inverter is reporting 0 volts from the PV during the day -- which was unusual. I disconnected the plus and minus solar cables from the inverter and directly measured the voltage using a voltmeter and I saw 0 again. The next day I climbed the roof to further inspect the issue. I discovered that the six panels on the east side are actually producing good voltage (something close to 200 V, which was reasonable given the position of the sun). But 0 was coming from the west side. I then disconnected all the east panels one by one and individually measured their voltages. 0 on all of them (one reported something like 4V but it is much lower than what it should be).
Talking to a few solar people in our town (not necessarily knowledgeable about the matter -- but they are in this business anyway), one suggested that the east side panels could have burned out the west side ones, especially if I left the system alone without any load. His argument was that when the east side panels produce more volts in the morning than the west side ones, they can burn out the west ones. Could this really be true? Isn't the purpose of parallel connections between the sets to deal with such situations. And this system worked like this for approximately 2 years -- why choose now to burn them out?
In any case, if there is a burn out, I would assume one of the diodes or panels to burn out first potentially protecting the rest in the series kind of acting like a circuit breaker. This could be wrong thinking, I know. Unfortunately, our roof has a steep slope and it is impossible for me to look at the back of the panels to check the diodes. I would have to bring them down, but this is a multi-people job that I cannot afford to do it right now.
To provide a few more clues, this was an unusually wet, rainy, and stormy winter around our off-grid home. Perhaps water got into some places that it shouldn't have? Does the fact that parallel connecting the working and non-working ones made the combined voltage 0 suggests that there is a short circuit somewhere? Do you think just leaving the system dry out and hoping for the best could bring my panels back?
Sorry for the detailed post, but I am miserable and clue to this mystery would be very welcome!
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