I have a single 120ah 12v battery in my caravan and have obtained the smartsolar 100/20 regulator. I see it says nominal power is 290w but im confused if that changes with all the different house panels available with different voltages. Battery will run fridge and a couple of led lights. Panel will be mounted flat on roof of caravan. What size or voltage panel should i be looking at?
So the charge controller will at nominal battery power 12v put out 12vx20a = 240w. But obviously on a 12v system your battery runs up to 13 or 14v so wattage yeilds will be a little higher. At 24 volts you can use more panels. As 20x24 =480w
You can over panel slightly (as in install 2x 300w panels- but you won't harvest 600W, so wasted power if you use panels that big) so long as you don't go over the input voltage 100v at min temperature for your area you will be fine.
If you get smaller panels and get closer to the 100v input as in 2x150w your charge controller will start up earlier with the higher string voltage but will always limit at max to the 20A output.
https://www.victronenergy.com/upload/software/VE-MPPT-Calc-3_7.xlsm
I have found this calc sheet useful especially the graph
I had a single 360w mono on mine for a while ran all the basic stuff quite well. Never saw the 360 for obvious reason. And just had to watch the heat from the charge controller.
https://www.victronenergy.com/mppt-calculator
This one is quicker, shows for 2x 175w victron modules a 100/20 is the recommendation.
Ok will look for a 300w. So with a higher voltage one means that it will work better with different temperatures?
With two panels in series whose voltage total is less than 100v at min temp, you will start charging earlier in the day and have another solar day.
But to be honest on a small system it's not so critical.
