Ask PYS: Power

Solar to Keep Batteries Topped Off – Scott, on Sep 16, 2015 asked:

I was reading your article in the June Pacific Yachting magazine regarding solar panels with interest. I looked at the flexible solar panels a few years ago and they did not seem like a feasible alternative at that time. It sounds like some recent improvements may warrant a re-look. We have a canvas only enclosure and trailer our boat from Canada to Lake Powell. I have four house batteries and two engine batteries (one for each engine). No gen set. When at anchor it seems our refrigerator is our highest draw which causes me to pull out my portable Honda 2000 to top off my batteries. I have a Pathmaker battery combiner for when we are underway but try to make sure my batteries are not down too far to avoid overheating my alternators. Is there a solution available now where I could put one of these flexible panels in that will keep my batteries topped off? Is the size feasible for my top? What is required from a wiring perspective?

Let’s assume you fridge draws between 50 Ah of power from your batteries a day. In order to meet this demand, I would suggest getting a solar array of 250 watts. To create a 250 watt solar array, you could use two 125 watts panels, each measuring about 58" X 27".

From a wiring perspective, each panel would be wired directly to its dedicated solar controller. In turn, each solar controller would be wired to a fuse connected directly at the batteries.