I was gifted a couple of 335 watt solar panels the produce 46.3V Voc, 37.9V Vmp, 8.8A Imp, 9.36A Isc. I have a 20 amp MPPT controller that might work but not sure as the info show 12 or 24 v operation. Is this considered a 24 v system?? This is going on camper shell to provide extra power when needed or if RV parked in shady spot. I was going to mount this spare MPPT and take some wires out to a connector so i can plug in large panel to put power to mppt controller to help charge up 2-6 v batteries. (12V) there will be several 12v panels of about 360 watts total which could be wire in series to make 24v system but do to shading issues my stay parallel. 'Not sure the best way to go on this system. I have checked voltage and with full sun it at like 46 volts DC (not hooked up to any thing just the leads)

carl2591 wrote:I have a 20 amp MPPT controller that might work but not sure as the info show 12 or 24 v operation. Is this considered a 24 v system?? That spec usually means it will charge a 12 or 24v battery system. What you need to research is whether it will take the panels' voltage, which is more than 24v. However, 20 amps isn't going to work as two of those in parallel will be 600 watts or about 50amps to batteries at 12v. It's possible it would work on a 24v battery system, but that's not what you have. You may be restricted to just one panel with that controlller.carl2591 wrote:there will be several 12v panels of about 360 watts total which could be wire in series to make 24v system but do to shading issues my stay parallel.I don't know where those fit in.

carl2591 wrote:I have a 20 amp MPPT controller that might work but not sure as the info show 12 or 24 v operation. Is this considered a 24 v system?? Armed with the spec's (model numbers) of everything, you need to contact the manufacturer of the controller. And/or look for a manual for the controller online.It would be a stroke of luck indeed if you find someone here who is intimately familiar with that equipment, especially since you haven't provided any model numbers.

You have 12V system because you have 12V battery bank."Normally" MPPT don't like being oveloaded too much, and one of these 335W panels would overload it already. So, - No.Sounds like you're planning a two-controller system, MPPT for 24V panels and PWM for several 12V panels. Too much pain (even if 20A MPPT would handle 335W). Go several parallel 12V with PWM like many before you, not many people do this for big arrays because big MPPT and 24V panels are easier in this case, but you can if you want.

You will need a new, larger MPPT controller even to use one of those panels. That 8.8A imp rating is for the 37 volt vmp output. An MPPT controller will be converting that down to your 12VDC system which will be about triple the amps....around 26amps I would guess, which exceeds the capacity of your current controller. .....and that is for just one of those panels you have!

My 30 amp WindyNation MPPT is limited to 400 solar watts 12 or 24 volts.

out what size charge controller for solar panels.??

33 Replies

Almot
Explorer III
Dec 26, 2017
You have 12V system because you have 12V battery bank.

"Normally" MPPT don't like being oveloaded too much, and one of these 335W panels would overload it already. So, - No.

Sounds like you're planning a two-controller system, MPPT for 24V panels and PWM for several 12V panels. Too much pain (even if 20A MPPT would handle 335W). Go several parallel 12V with PWM like many before you, not many people do this for big arrays because big MPPT and 24V panels are easier in this case, but you can if you want.
Sam_Spade
Explorer
Dec 26, 2017
carl2591 wrote:

I have a 20 amp MPPT controller that might work but not sure as the info show 12 or 24 v operation. Is this considered a 24 v system??

Armed with the spec's (model numbers) of everything, you need to contact the manufacturer of the controller. And/or look for a manual for the controller online.

It would be a stroke of luck indeed if you find someone here who is intimately familiar with that equipment, especially since you haven't provided any model numbers.
2oldman
Explorer II
Dec 26, 2017
carl2591 wrote:
I have a 20 amp MPPT controller that might work but not sure as the info show 12 or 24 v operation. Is this considered a 24 v system??
That spec usually means it will charge a 12 or 24v battery system. What you need to research is whether it will take the panels' voltage, which is more than 24v. However, 20 amps isn't going to work as two of those in parallel will be 600 watts or about 50amps to batteries at 12v. It's possible it would work on a 24v battery system, but that's not what you have. You may be restricted to just one panel with that controlller.
carl2591 wrote:
there will be several 12v panels of about 360 watts total which could be wire in series to make 24v system but do to shading issues my stay parallel.
I don't know where those fit in.

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out what size charge controller for solar panels.??

33 Replies

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