Have gone all summer on 6 - 100 W panels, 21.6 Voc, in parallel, connected to an MPPT 100/50 into a 600 AH LFP house bank. Everything working perfectly, the system has been installed for two years on my boat. Updated to a firmware prompt a few days ago (V1.57) and just noticed the PV voltage is way below sufficient to charge the batteries. Open Circuit from the panels reads 18V this afternoon, PV voltage on the MPPT is 5.78V at best. Disconnect from the MPPT an back to 18V, voltage drops dramatically when reconnected to the MPPT.
Borrowed a friend’s MPPT 15/15 and the result is the same. Good Voc until connected to the MPPT, then volts drop (assuming under load.) What’s wrong with this picture?
Insights appreciated...
