I have a boat fitted with 4x 105ah batteries coupled with a Victron multiplus 3kw 120a 12v charger/inverter.
I want to fit 4x 460watt solar panels coupled to a Vicctron MPPT contoller.
My questions are-
What size controller should I buy?
Do I connect the controller direct to the battery bank through a fuse?
How do I ensure that the solar takes precedence over the mains hook up to charge the batteries?
For that size of panel (4 x 460W) = 1840W total, the charge current will be at max 140A. In your case I would suggest 2 controllers of 60 to 70A each. If you go with 2 x 60A controllers then you would loose a little bit of peak sun at mid day in the summer but be OK for most of the time.
Try the Victron MPPT calculator to get the correct type using the proposed panel details of voltage and current because this will set the recommended charger.
You connect the controller positive direct to the battery bank through a suitable fuse. If you have a battery monitor / shunt then the solar negative goes to the system side of the shunt, otherwise to the battery negative.
The simple way is to set the absorption and float voltages on the controller 0.1V higher than the Multiplus settings so the batteries are charged by solar. Note, ac loads will always come from the grid even if you have loads of solar. You will have to either turn off the shorepower if you want the solar to provide ac loads also. You may be able to program something using assistants but I do not know exactly what.
Thanks for your quick reply.
I did use the calculator and wanted to use the 250/100 model.
The calculator indicated that that model was nor compatible with my proposed set up.
Can you explain why?
Thanks
Only if you give the exact panel model the specs for Voc, Isc, Vmp and Imp.
These are the panels I was hoping to use-
Aiko Neostar 2S 460W N-Type ABC, Gen 2, 54 Cell, All Black.
Had a quick look, 4 panels in series they are well within the spec of the 250/100. I chose London and default cable details and temperature and it said the array was 127% oversized. If your details are different by the smallest amount it could come up with the array being above 130% oversized and the default option on the start page is to limit to 130%. Uncheck that box and then see.
