Good evening everyone,
I have 2 strings of 7 panels each on the MPPT RS 450/100
Im planning to add more ,should I make it 2x9 panels or 2x10?
What margin of safety to keep regarding max Voc?
Panels are canadian solar 410w -Voc 37.2,Isc 14.01
asked
Add 6 panels to MPPT RS 450/100
@ukXan As per the manual re note 1, what is your battery float voltage?
Voc goes up with lower temperatures. What is the lowest temp your array will experience?
Perhaps use the mppt calculator?
Well,given Im in East Anglia,in spite of global warming the temp did drop to -6 I believe on 1 day this winter.
Pylontech battery float as per victron documentation is 51 V
Many thanks,
It would be fine since the highest Voc even at -6C would be 402V with 10 of those panels in series. The issue you would have is with 2 strings of 10 panels in series would result in rated power of 8200W. Each tracker on the MPPT RS can only handle max of 4000W so you'd potentially lose over half the power. It would be much better to keep it to single string of 10 for both trackers. Even then you will run into the maximum amperage of MPPT RS of 100A since that 8200W would be well over 100A charging capability. Everything would still work you will just be losing a lot of potential power if you need it.
410 x 10 = 4100 each tracker but realistically you wont get near that in the winter only in the summer (what i have seen) but in the summer you won't use so much battery so bulk charge wont last to long before you go on absorption and the mppt wont try to pull full power from the panels.
This is just what i have seen and not a recommendation or suggestion you need to make up your own mind.
Don't mix PV power with MPPT output power. If there's excess available it's lost. It's advantageous to add more PV capacity than the controller output to give adequate output in poor light. The thing to watch is Isc ratings. Determining the cost effectiveness of the approach is a different issue.
