After living with both solar and wind power on anchor and on moorings we are considering replacing the 64-watt panel with a new 130-watt solar panel because it is about the same size (10 square feet) as the existing panel. Like many modern voyagers we have managed to squeeze a full complement of electric and electronic equipment aboard our vintage 34-foot Tartan sloop. We use an average of 110 amp-hours of electric energy per day. When it’s hotter than 95° F the 12-volt refrigerator operates longer, and our daily use increases to about 125 amp-hours. We know about our daily usage because we installed a Link 10 battery monitor last year along with 330 amp-hours of new Trojan house batteries. We only operate our Honda 2000 generator to top-off our batteries when we’ve gained as much energy as possible from sun and wind.
The question is do we keep the wind generator if we double the wattage of the solar panel?
We’ve learned a couple of things about our existing solar panel. First, it’s important to have the panel adjustable to the angle of the sun: the daily output is doubled as the panel is orientated as close to 90° to the sun as possible. It’s hard to note the difference in solar panel output having more than four panel adjustments including laying the panel flat on the dodger when the sun is nearly overhead. When we’re on board, solar panel adjustment has become part of our daily routine. When we’re ashore we set the panel at a modest angle, either fore or aft depending on which way the boat is pointing, knowing the sun will move overhead while we’re off the boat.
We’re now considering a new 130-watt Kyocera solar panel that will fit on top of the dodger and can easily be made to work with the existing adjustment mechanism. The new Kyocera panel costs $600 (retail) that computes to $4.60/watt, interestingly about the same as the cost per watt 5 years ago. We’re expecting the new panel to produce a maximum of seven to eight amps or 50 amp-hours each day, about half our daily amp-hour requirements. Now our Honda 2000 should run about one-third less time. We hope to sell the 64-watt Uni-Solar panel and defray some of the cost of the new one.
We have lived with our Air-X Marine 400-watt wind generator for four years. It does the job and is reliable but it needs at least 13 knots of wind to generate a meaningful amount of electric current. We get a little more than two amps at 13 knots and 20 amps at 25-plus knots of wind. (Solar photovoltaic panel output is linear whereas the wind generation amp output is non-linear.)
Being an electrical engineer I probably examine our on board energy systems more than most voyagers and likely bore our friends. Our plan is to double the size of the solar panel and remove the wind generator. I’ve concluded that a 130-watt solar panel will reliably provide much more energy over a six-month cruise than the 400-watt wind generator. My advice is that cruisers seriously consider the new generation of high-output solar panels and devote as much space as possible. It’s even better if they can be mechanically orientated toward the sun. On top of the bimini seems to be a popular location.
— Richard de Grasse holds a USCG Masters license, is a Commodore in the Seven Seas Cruising Association and a member of the Ocean Cruising Club. He and his first mate Kathy live in Islesboro, Maine, when not voyaging.