question

darrien28 avatar image
darrien28 asked

VIC 100/30MPPT: 12V/440w vs 24/880w

Hi there :-)

Having had a good look around, I think I need to ask my question with my own words, for certainties sake!


I'm setting up a 12v battery bank. 300 amp hours to begin with.


I understand and am confident that with 440w of solar panels (12v) this will work fine.

My question is, does the nature of MPPT mean that I could connect up to 880watts of 24volt panels, and it would still work OK? (My intention here is to compensate for cloudy days and have fewer panels in general.....especially if I change the battery bank for a larger one down the track...)


Am I thinking correctly?


Many thanks!


Danny. NZ :-)

MPPT Controllers
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

With the 30A 100V MPPT, you can use 360W @ 12V, 720W @ 24V, 1.08kW @ 36V etc, with a little to spare for the converter inefficiency.

formula is: I bat x V batt x 1.1 to 1.15

I bat is limited by the MPPT model.

1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Vance Mitchell avatar image Vance Mitchell commented ·
The 100/30 and 100/50 are only 12/24v. If you require 36 or 48v you need either the 100/20 or the 150/35 and above.
0 Likes 0 ·
Vance Mitchell avatar image
Vance Mitchell answered ·

The main thing to remember with Victron MPPT controllers is that the Voc from your panels must never exceed the first number, in this case 100v

The second number indicates the maximum current that will be charging your batteries and supplying any load. 30A in your case.

You can oversize your panels a bit to allow for bad weather, and other things which reduce their efficiency.

If you are staying with a 12v battery then you can only use 440w of solar input regardless of if the panels are 12v or 24v. Oversizing to 600w or so generally won’t cause you any issues as long as you stay within the controller specs. (Max 35A panel current on the 100/30)

So for your 12v battery 600w would need to be with a panel voltage (Voc) of 20-90V.


1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

darrien28 avatar image darrien28 commented ·
That is the succinct answer and explanation I needed - thank you very much Vance! I really appreciate it!!!!
0 Likes 0 ·