I have a roof mounted grid tied system: 20 each Sharp ND-L3E1U panels (123W panels connected in series) and a Sunny Boy SWR2500U inverter. It's worked flawlessly for the last 15 years.
A couple of weeks ago I noticed that the the inverter display indicated that the array was producing 395V and 0 watts (I use the old fashion monitoring system of looking at the inverter display once a week or so). The voltage was consistent with historic values, but obviously the watts was not. Everything appeared to be working (the inverter wasn't showing any error codes) - except that I wasn't getting any power.
I tried "rebooting" the system by turning off the AC and DC inputs. That didn't changing anything. I was fortunate to get an identical SB2500 inverter a few years ago form a working system that was being upgraded - I replaced the inverter and the results were the same - about 395 volts and no watts. I tested the continuity of the wires from AC connection to the house panel and the inverter to the roof - the wires are OK. I checked the line voltage - its OK (244V (122V each leg) and 60 Hz).
I visually inspected the panels and wiring connections and did not see any obvious issues.
The last thing I've tried was disconnecting each panel from the array and testing Voc and Isc using my multimeter. Every panel's output voltage was close to the the manufacturer's spec of 21.3V. Current output varied from 3-6A for each panel (I tried to measure the output in direct sun, but that was hard due to time constraints - spec is 8.1A). I have not tested each panel under load (because I'm trying to avoid that until its absolutely necessary).
I've read on this and other forums that I might have a panel that has failed. If so, the failed panel is letting a small amount of current pass so I get voltage, but not enough current to pass to produce measurable watts.
Any suggestions about what is causing the issue?
Any Idea , Suggestions would be appreciated,
Hi RyanCaleb thanks for your question. Maybe Moustafa Adly or Moe Khajavi might be able to help.
Als Antwort auf Moustafa Adly:
I agree with Moustafa. One faulty solar panel "chokes" the output from all others in the string, they will produce voltage normally but little or no current. If all panels are OK it's likely an inverter issue.