July 11, 20224 yr Guys. I encountered this problem and still dont understand the cause. I was called by a client, They had aa Kodak OGplus 5.48 offgrid inverter (5kW 48VDC), Mppt V Range 60-115VDC, PV in Max 4kW. Pylontech 48VDC, 2.4kWhr Li-Ion Battery 6 panels, 345Wp, Voc 41.76V, Vmpp 34.99A, Isc 10.54A, Impp 9.86Aa, Brand Ja Solar. Configuration was 3 modules in series, then 2 such strings in parallel The system was also paralled with utility programmed to prioritise solar for loads and only utility when solr is not sufficient His worry was that he was not benefiting from solar. He still had the same cost of power and when utility is down his battery was not lasting much time. When we went ther we recomended he upgrade is battery and add more solar panels. He had an extra Ja Sola module 345W with above specs. So he bought 5 more panels. Unfortunately these Ja Sola 345 wher no longer on the market. So he got 374W Jinko Modules with the following specs 375Wp, Voc 41.12V, Vmpp 34.53A, Isc 11.59A, Impp 10.86Aa. So we added 6 more panels (5 x 375W and 1 x 345W) Configuration, 3 in series and 2 such strings in Parallel. So we now had 4 strings in parallel to the inverter. But on commissioning we realised the inverter was getting only around 1.5kW from the panels and it would take balance from utility. This was so weird as the PV plant capacity was supposed to be more than 1.5kW On troubleshooting why it was behaving so, i switched of main utility MCB to simulate a condition where we do have utility. And we started loading the system bit by bit by switching on different appliances at a time. 1. We started with 1 AC and load was around 700W, and all coming from solar panels 2. We switched on another AC and load was around 1.6kW, and all coming from solar panels 3. We then switched on a kettle (water heater) and load went to 3.7kW, and all coming from panels. Then we thought we had won, then switched off kettle and the 1 AC. AAfter about 3 min, we had a slight boom from the inverter and some smoke. We opened the inverter and realised some transistors on the PV Input card were burnt. I removed that inverter to take it for repair, then took an exact similar unit and went to install it. I did the installation in the evening and left the client running on utility, The following morning when the sun came up and the system switched to solar the inverter went up in smoke again, the same card had been burnt. II have repaired one of those inverters but i need to know whats causing that before re-install it. I have reseached all angles but um hitting dead ends. Has any1 encountered such, help me team.... PPoint to note: the first installer did not put external surge protection and DC MCBs for the PV and Battery Circuits. Client is very conservative when we came in and suggested such he said its been working like that lets leave it. All the 4 strings are combined on the roof and only one set of cables coming down to the inverter. Cable size is 6sqr . mm
July 11, 20224 yr 30 minutes ago, Graham Muvirimi said: 6 panels, 345Wp, Voc 41.76V, Vmpp 34.99A, Isc 10.54A, Impp 9.86Aa, Brand Ja Solar. Configuration was 3 modules in series, then 2 such strings in parallel 3 in series 2 strings paralel would give you voc of 120v that would be above the mppt spec (Mppt V Range 60-115VDC) Voltage above spec is a killer. Should have been 2s 3p then you would not get that magic smoke.
July 11, 20224 yr 6 hours ago, WannabeSolarSparky said: 3 in series 2 strings paralel would give you voc of 120v that would be above the mppt spec (Mppt V Range 60-115VDC) Voltage above spec is a killer. Should have been 2s 3p then you would not get that magic smoke. Having 120V when the Voc max is 145V should not damage the MPPT. If the temp was not very low you would not even get to the Voc. During the recent minus 4 deg cold spel my panels did not even reach their Voc as per spec at 25 deg Just one thing the string with the 345W in series will throttle the 375W but just a little bit. Edited July 11, 20224 yr by Scorp007
July 11, 20224 yr 1 hour ago, YellowTapemeasure said: Are they 72 cell panels? Model numbers? And check @Coulomb signature... Refer to OP where the main basic specs were provided for calcs.
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