Tag Archives: Hunter 376 Solar

Sunshine And The Fine Art Of Boom Management

Last Monday at 0900, I turned off the breaker to our onboard battery charger. Since then, our refrigerator and freezer, lights, water, stereo, fans, indeed our entire DC electrical system, has been running solely on solar energy that we’ve captured and stored. In the days between then and now, we’ve seen a mix of sun, clouds and rain. I’ve followed the system’s operation closely. The day’s first trickle of power starts flowing into our battery bank a little before 0730, and the panels don’t shut down and go to sleep until about 5 PM. So far the peak power generation I’ve seen in bright sun at midday is just a touch shy of 20 amps. I designed our solar array to put out over 30 amps, but since it’s only mid-February and the sun is pretty low in the sky (and the panels are often being shadowed by the masts of surrounding boats), I’m confident we’ll get closer to and maybe even exceed our design goal once we head further south.Solar2

It’s now exactly one week later, and after seven days unplugged, our bank reads 87.2% full. The charging day is just beginning, so even though it’s supposed to remain cloudy today, I expect our bank to be above 95% full by dinnertime. My goal was to create a system that would eliminate the need to run our generator or engine to charge our batteries. I believe we’ve succeeded. 🙂

Also, on Monday afternoon a strong front blew through with 40+ knot winds. The method we worked out to mount our flexible solar panels to our fabric Bimini survived the gusts with no hint of lifting or flapping.Bimini5

One thing I didn’t sufficiently appreciate though until we actually activated our array is just how sensitive solar panels are to shadowing. I found that the shadow cast on the panels by the boom could drop the system’s total output by up to 60%.  Getting the most out of our system means that in the morning, I have to pull the boom to its starboard-most position to get its shadow off the panels. In early afternoon, it has to be pulled all the way to port as the sun moves west in the sky. So we’ve learned that proper boom (shadow) management is now going to be a part of our daily routine if we want to keep the solar juice flowing and the bank topped off.Solar3

I’ll soon do another post in our More Power, Scotty! series to give some of the technical details of how we integrated solar charging into our onboard electrical system.