My existing semi-flexible panels are failing and I bought a set of three BougeRV panels (https://www.bougerv.com/products/arch-pro-12v-24v-200w-flexible-solar-panel?variant=50760065056984) figuring that three of these in series would give me a max of 93V and 20A, which would be compatible with my existing MPPT 100/30. However I have since found the Victron MPPT Calculator and figured out that I should most likely have used the open circuit values for the panels (36.4V and 6.7A per panel) which add up to 109.2V and 20.1V – slightly about the rated voltage for the MPPT 100/30 I have.
While this feels like a borderline case, I don’t really know when the open circuit voltage occurs but I would hate burning up a component because of this.
When I enter the data I have for the Bouge panels into the Victron MPPT calculator, it recommends the MPPT 150/35. Would my new panels still be within telorance for the existing MPPT 100/30 or do I need to upgrade to the 150/35? From the documentation I gather that the dimensions of the two units are the same.
I had a fast look at the panel data, and I’m sorry to say you definitely cannot use 3 with the 100/30. The 100/30 maximum voltage is absolutely 100V.
The spec is actually 36.4 +/- 5% so if we add that tolerance of 5%, = 36.4 * 1.05 = 38.22V times 3 panels = 114.7V
Then factor in the cold weather (not sure how bad it is where you are, but let’s pretend the equipment is outside in a Canadian winter at -40C.) and then its gets even worse as the panels will produce more when cold.
You could do 2 panels in series, not 3. OR 3 in parallel, but it might take a while to get the necessary +5V above battery for the startup voltage.
Just to reinforce the answer above, 100V is a hard limit, exceed this and you will most likely destroy your controller.
If you go to the 150/35 you should be OK. If you used the Victron MPPT Calculator then make sure that you input your panel temperature coefficients and your lowest temperature.
Voc occurs when the batteries are full or close to full, the controller then stops charging by letting the panel voltage rise to Voc so the current flow is reduced.