Hi,
Also consider where you place the MPPT controller. The panels provide a 30V output (max) but the MPPT controller will convert this to 12V (nominal) for your
batteries. Place the controller as close as practical to the batteries to reduce losses due to voltage drop because the
current will increase. You need to make sure the wiring can accept this higher
current. Ideally place the controller within about 3 feet of the batteries. This way you reduce the losses in your wiring (as said make this thicker than the minimum required) and get the best possible
charging. We have a Moody 36 fitted with a 12v system and a 360AH domestic battery bank. Our two 130AH 24V panels are wired in series and provide a max 48V OP (we often see 50A plus here in the
Med peak in summer). The run of AWG 10 solar wire from panels to MPPT controller is about 9m (28'). The controller is less than 1m from the battery bank and uses the same cable. We spend a of of time at
anchor and we recharge our batteries (from 75%) by 1100h on most days even in cloudy conditions. Only on two occasions last year did we need to run the
engine and those were on really stormy days. (we are a low
electrical usage
boat but still charge a computer daily as I am a writer). By using 24V panels and converting at the latest possible moment to 12V we have reduced the current flowing through the
cables which are overrated. This gives us the maximum possible efficiency. This scheme was advise by the technical department of Midsummer Energy who supplied the system. Also use the MP4 connectors. They have now been out in all weathers for 2-years without any problem.
SY Tiger Bay