Samsonite801
Solar Wizard
- Joined
- Oct 15, 2020
- Messages
- 2,988
Bought two 6500w MPP 6548 inverters. 12 TrinaSolar 330W panels, and three 48v BigBatteries each 103Ah.
Original plan was to power two campers off grid, One 50A the other 30A.
Was told this system would be enough.
Problem I have run into is lost power to the 30A camper, which is the only one connected now. (It is only using one of the inverters, as it is connected to L2).
Have monitored battery level, and after running the Class C A/C over night, and next morning Victron shunt showed 97% left.
Thought I had it made.
But about 6 hours later, with good Florida sun, power cut off. Batteries went down to cutoff setting of 44V. Had good sun angle, and not sure what's up.
Each string of three panels put out about 110vdc to the combiner box. But the inverter only registers 90vdc or so. Not sure why, as I have good quality wires.
Anybody else have a similar system, and have any problems?
Internet reviews only have praise for the system. I think I have something good, but not too sure now.
I'd also check for the correct calibration of your shunt (and watch voltage too while confirming the SoC % at least kind of lines up)...
I know just today on my setup (got up to 98° F here), I only had 1 of my 2 Dometic roof AC units running all day (it's all my 2800w inverter can do), and at around 4:30pm I started dipping into battery already (4s 405w pointing more East, 4s 405w pointing more West with separate charge controllers), and right now at 6:55pm (Sun is still up) with AC still running, my Victron BMV shunt is showing SoC already down to 88% (Time Remaining is showing 8 hours until it hits 20% as the low trigger) and I have 1680 AH of battery (22 KWh), so it doesn't seem right you were actually at 97% when you saw that indication (after running the AC all night). What's the amp draw on your AC unit?
Also, do you have a backup generator for charging? It should be for emergency only, I haven't had to start mine yet since I got the bigger solar going, but it's there with 120 amps of battery charging in case I get into a pickle (mine is only a 12v system but I'm off-grid so I consider a generator for redundancy an important feature for WAF).
Also on your question about solar voltage at 90v. Of course we'd have to know all the specs and wiring layout of your solar panels and array, but if the circuit is active (being controlled by the charge controller MPPT logic), the voltage will draw down and fluctuate, as MPPT logic can pull down voltage a great deal to increase amps while as it finds maximum power point in watts (it's a very dynamic circuit)..
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