Is this panel 12 or 24 volt ?

[Cabinfever]

I will be using this 425 watt panel at my off grid cabin. Can this panel be used for a 24 volt system ? If so, would it be best used in a 24 volt system or just stick with using it with a 12 volt system. I need to get the most out of this panel possible without purchasing another panel. I plan on using it with an MPP all in one or similar product. Please see attached the photo of specs from back of panel as well as pdf data sheet. Many thanks for your help.

 

[ereams65]

Based on my limited knowledge, I think 24v would actually be the preferred route with this panel. It's capable of more according to the specs.

 

[Cabinfever]

Based on my limited knowledge, I think 24v would actually be the preferred route with this panel. It's capable of more according to the specs.

Thanks for you input, anyone else please chime in as your answers will allow me to go ahead and order my system accordingly.

 

[rickst29]

Your MPPT controller can support either of those battery bank voltages, but you can have smaller wiring losses (between the MPPT and the battery bank, and between the battery bank and an inverter) by sizing the battery bank at 24V. You can also buy a "smaller" MPPT controller, because they are sized and priced according to the current capability - and charging into a 12V battery bank needs to use twice as much current to yield the same power, in all charging situations. Because the current is half as much, you can also use smaller wires between the MPPT and the battery bank.

But the issue with a 24v battery bank is the fact that so many DC devices are built to run at 12v (not 24v). If you have a lot of 12v devices, then the double conversion (Solar to 24v battery, and then 24v to 12v) is more costly than buying bigger wires and going directly to 12v. But if you're in a cabin, and always using 120v through an inverter with no "12 VDC" devices, then a 24 Volt configuration wins. It has better performance and allows for slightly smaller wires.

In my RV, my own Solar Panels are about 80 volts. But I built my batteries as "12V" LFP, and set my controller to run the battery bank at that voltage (12.8V nominal, 13.7 - 14.4 charging voltage). I did that and used larger wires, in order to run a lot of "12v" appliances directly from the battery, without adding another step-down to run those "12v" appliances and components.

 

[Cabinfever]

Your MPPT controller can support either of those battery bank voltages, but you can have smaller wiring losses (between the MPPT and the battery bank, and between the battery bank and an inverter) by sizing the battery bank at 24V. You can also buy a "smaller" MPPT controller, because they are sized and priced according to the current capability - and charging into a 12V battery bank needs to use twice as much current to yield the same power, in all charging situations. Because the current is half as much, you can also use smaller wires between the MPPT and the battery bank.

But the issue with a 24v battery bank is the fact that so many DC devices are built to run at 12v (not 24v). If you have a lot of 12v devices, then the double conversion (Solar to 24v battery, and then 24v to 12v) is more costly than buying bigger wires and going directly to 12v. But if you're in a cabin, and always using 120v through an inverter with no "12 VDC" devices, then a 24 Volt configuration wins. It has better performance and allows for slightly smaller wires.

In my RV, my own Solar Panels are about 80 volts. But I built my batteries as "12V" LFP, and set my controller to run the battery bank at that voltage (12.8V nominal, 13.7 - 14.4 charging voltage). I did that and used larger wires, in order to run a lot of "12v" appliances directly from the battery, without adding another step-down to run those "12v" appliances and components.

Thanks for the information. I do not have any 12 v equipment. I plan on purchasing an all in one MPP or Growatt which will tie directly into my AC cabin wiring and use my generator as a power source to charge batteries when required.

 

[Wibla]

I plan on purchasing an all in one MPP or Growatt which will tie directly into my AC cabin wiring and use my generator as a power source to charge batteries when required.

You'll want to go 24V then, or get more solar and go 48V, especially if you're considering running a fridge off solar.

 

[MisterSandals]

I plan on purchasing an all in one MPP or Growatt which will tie directly into my AC cabin wiring and use my generator as a power source to charge batteries when required.

So how much AC power does your cabin need? How big is your battery bank and what chemistry (lead acid or lithium or ??).