I am mounting four 200w 12v solar panels on the roof of my ambulance conversion. I have a 40a mppt charge controllerbut I am considering adding a combiner box on the roof near the panels before the run into the ambulance and the charge controller, besides simplifying things connection wise, added fuses for each panel and a breaker/switch before the charge controller are there other pros? Any cons? The setup came with a single 20a in line fuse. The combiner box I'm looking at has a 15a fuse for each panel and a 63a breaker. Will this limit my input to the charge controller?
Combiner box or branch connectors?
- Thread starter Tanselow
- Start date
Herbie
Rendezvous Conspirator
There are a lot of real world variables, but for basic spec purposes, back-of-the-envelope math is useful:
200w panel @ 12v = 16.666A
4x 200w panel = 66.666A
Now granted, these are nominal values - realistically the panel will be outputting a higher voltage, but at peak output (cold, sunny day) could also put out more than 200w. Point being, you probably want a little margin built in - even 60A is likely underrated.
DaveInDenver
Middle Income Semi-Redneck
The A-hr isn't important in this calculation.
You say the kit came with 4 x 200 watt panels and a 40 A controller? Can you link to something that shows this kit?
I wonder if the controller has an exceptional high maximum voltage (you are absolutely sure it's MPPT?) and expects 12V panels to be wired in series. The controller would need to tolerate on the order of 100V.
This might also explain the 20 amp fuse.
It's also possible the panels are high voltage, 24V, 36V or even 48V nominal thus 8A, 5A or less amps. A photo of the panel label or the kit link would be useful.
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Herbie
Rendezvous Conspirator
Or Series-Parallel - like two parallel pairs of 2x12v panels in series for a "24v" nominal input at 33A?
DaveInDenver
Middle Income Semi-Redneck
Yeah, indeed. If it's a packaged kit then it seems like there's got to be more to it. Especially if the controller is MPPT running higher voltage and reducing current is better anyway.
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