“Are you building the ultrasonic anti-fouling unit for your boat? You will need a solar panel and a charge controller to keep the batteries topped up. Or are you thinking of a large solar panel for your caravan or 4-wheel drive? Again, you will need a solar charge controller. This is the one to build.
by John Clarke”
I stumbled upon an interesting How-To guide today for those who may be interested in building their own MPPT solar charge controller: