I´ve got a mppt 100/50 12/24v controller that after a few weeks it doesn’t seem to want to charge. Nothing has changed in my setup during this time and given my beginner status, I am a bit stumped. I have two 275w panels hooked up to a pair of Renogy 3 to 1 branch connectors with 20A in-line fuses on each of the panel’s positive lines, and then to the MPPT using two 10ft 10awg cables. Cables are using crimped ferrules on the mppt end and all connections feel tight and secure. With it being fall here, the sunlight isn’t awesome, but measure with the multimeter shows ~40v and 2-3A from each panel. If I probe the screw terminals at the MPPT, I get 2-3V (have not measured amps).
In doing some reading on the forum here, I understand that it may be a bad connection somewhere and the multi-meter doesn’t use enough current to verify this. To eliminate some of the connections, I tested each panel on its own with just the 10ft 10awg cable connected and the results were the same, however that does not help if it is a multi-meter current issue.
What would be the correct/foolproof way to test to try and verify that the cables are, or are not, the issue?
Assuming these connectors are putting the modules in parallel?
A Better move would be to ditch both the fuses and the branch connectors, and connect the 2 modules in series. At the same time as you rewire this, remove the battery power from the MPPT unit and use an ohm meter to measure the PV input to see if this has gone short circuit.
The usual source of this type of problem is an oxidised contact or a damaged wire.
I swear I tested this before with no success, but it seems that by removing the 3-to-1 branch connectors I once again have input to the MPPT. There must be a loose connection in one of them because after putting everything back together the way it was, it worked again as well. I once again pulled it apart to route the cables back to their original locations and then put it back together, it again did not work. Leaving the cables routed in the proper locations plus removing the 3-to-1 again, and then I have power through the mppt once more. Jeepers!
The only thing now is that the voltage is at 80+V already and the panels/sun are not in an optimal position. I assume in good sunlight I’ll be bumping up against the 100V limit of the MPPT? I had also planned on possibly adding a third panel at some point which was the reason I was going parallel in the first place, I assume this would be somewhat pointless if I was to go series. (unless I were to get a second MPPT controller)
looks like you have a lose or burnt connection on one of the cables from the mppt to the 3:1 connector. As a professional installer, I do NOT like these splitters - they always cause problems.
Check the back of the modules for the Voc rating, this will determine the max voltage, subject to temperature. (Voc increases by a small % with temperature, spec is at 25C). 2 modules in series is usually ok for a 100V MPPT, if you want to add a third module you will need to upgrade to a 150V mppt if you stick with the series route.
It seems like using these panels in series is starting to give me alerts of “#33 Input high voltage” for the “SmartSolar Charger MPPT 100/50” on my raspberry pi w/ Venus OS. Specs on the panels are as follows
Pmax: 275 W
Voc: 24.88 V
Vmp: 21.24 V
Isc: 13.58 A
Imp: 12.94 A
Module Efficiency: 20.4%
Looking at the MPPT history, it looks like Max voltage is reaching 102V. Is this a concern? Right now, I am sitting just under the 100V threshold but at very low current, sometimes zero (I believe the low Amps is due to a combo of battery being full, shore power being connected, and it being very cloudy?). Forgive my ignorance, but how am I reaching close to, and sometimes over 100V with these panels?