February 22, 20233 yr Question for the Technical Experts: What will happen if the solar array Negative is mistakenly solidly grounded. Will this fault cause the inverter to blow?
February 22, 20233 yr 2 hours ago, Carl said: Question for the Technical Experts: What will happen if the solar array Negative is mistakenly solidly grounded. Will this fault cause the inverter to blow? Yes, its a very unforgiving failure, because the neatral is also grounded, the full bridge converter now gets shorted, and mostly leads to the full bridge IGBTs getting destroyed.
February 22, 20233 yr I guess it should although I have seen various methods of earthing,bonded LN and separate and got me confused. This house is build in 70's and I am not sure about how electrical sistem was made because it hard to find out,all the cable are in the walls. I am pretty sure I don't have earth rod in my yard. Measurements show same voltage between L-N and L-earth. between N-earth is zero,maybe 1v,2v but it is a cheap multimeter. Is there a way to measure N- earth bond with diode function of multimeter since there is no voltage or very low? Or it burns my multimeter?
February 22, 20233 yr 2 hours ago, Ciprian said: Is there a way to measure N- earth bond with diode function of multimeter since there is no voltage or very low? Or it burns my multimeter? No, don't do that. It's not easy to check the neutral to earth bond. The fact that you see little voltage from neutral to earth is a good sign.
February 22, 20233 yr Ok. I read the manual of the inverter and because the topology of the inverter is non-isolated is restricted the use o grounded solar panels. What I understood is grounded panel is when + or - of the panel is connected to frame and to earth, correct? My panels are Trina solar 250w, I mounted to frame on the roof of the house and I did not earth the frame though there is earthing sign on the frame of each panel. Can earth the frame of each panel? And earthing of the frame should be separated from the grid earth? I am new to solar and in my country are few skilled electricians which worked with solar but they do not want to provide answers unless they come to do it and are always busy.
February 23, 20233 yr 11 hours ago, Ciprian said: I read the manual of the inverter and because the topology of the inverter is non-isolated is restricted the use o grounded solar panels. My understanding is that ideally you should always ground your panels if you have high voltage (more than 120 VDC). However, cheaper panels don't seal against moisture properly, so you end up with problems when you have the high voltage strings, so the inverter manufacturer recommends not earthing the panels. These inverters don't have insulation monitoring (as ordinary grid interactive string inverters must), which in my opinion makes them less safe. What I would do is to ground the panels and hope that you have good panels. If you find problems like fault code 08 (bus voltage too high) when it rains, then you have little choice other than to remove the grounding, try to find and repair or replace the electrically leaky panels, or replace the inverter. But nearly all high PV voltage inverters are non-isolated, so you may have the same or similar problems with the next inverter. 11 hours ago, Ciprian said: What I understood is grounded panel is when + or - of the panel is connected to frame and to earth, correct? No, panels never connect one end electrically to the frame. What happens is that moisture gets in where it should not, and forms a high resistance path from somewhere in the panel's string of cells to the frame. With high PV voltages, even a high resistance path to the frames can cause big problems. When the manual talks about a "grounded panel", it means that the frame is wired to a solid earth. 11 hours ago, Ciprian said: And earthing of the frame should be separated from the grid earth? I'd say so. Connecting to grid earth could cause nuisance trips of residual current devices (RCDs). I have extra low voltage panels, so it's not an issue for me.
February 23, 20233 yr Thank you for replies. I have 10 panels, mounted only 9 in series with about 340 Voc so is quite high voltage. After this discussion I think I will earth the frame separately
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