How Much Solar Do I Need to Charge a 200 Amp Hour Battery Bank?

Question:

Hi Jeff, our mooring has no shorepower and we would like to install a 200 amp hour house bank. We typically motor for an hour to return to our mooring so the charge from the standard 80 amp alternator won't be enough to recharge the bank if we're at 50% depth of discharge (DOD). What size solar panel would we need to fully recharge the bank and also avoid sulfation due to low recharge currents? We're thinking flooded lead acid batteries (FLA) as we understand this has a lower minimum charge rate than AGM. No problem if the charge takes a few days. Thankyou. - Rob

Answer:

Sizing solar panels on boats typically comes down to how much space is available to mount them and re-charging is based on the controllers we select.  For example, a system with two 155 watt solar panels and a Victron MPPT controller will produce around 100 amp hours on a sunny day

We have seen an increase in boaters choosing lithium for their vessels due to the energy density and light weight build, they allow for deeper discharge and can sit in partial state of charge for long periods of time with out doing damage. While they do accept an even high charge rate than an AGM, it is not required.