A sailboat named Groovy has been equipped with a solar power system that powers the boat’s refrigerator, freezer, laptops, a 22″ TV, a stereo, and more. And this isn’t the couple’s first solar-powered mobile home.
“My husband and I have been traveling full-time by sailboat and RV for the past 6 years, and we have lived entirely off of solar power in our trailer and sailboat,” Emily Fagan wrote in a message in CleanTechnica‘s Solar Energy Google+ community. Emily and her husband lived in two solar-powered RVs before the sailboat. Now that they live in the sailboat, Emily writes, “we haven’t plugged in to shore power since September, 2011.”
Groovy is a Hunter 44DS sailboat. It is equipped with the following:
- Three 185 watt, 24 volt Kyocera solar panels, totaling 555 watts. These are wired in parallel to avoid the impact that shading has on the solar panels. Great idea for this boat, which is shaded by a mast!
- Combiner box: This connects the three solar panels’s wires to one charge controller.
- A Xantrex 60 amp MPPT charge controller.
- A 600 watt pure sine wave inverter. Pure sine wave inverters are the best and can successfully power everything, including refrigerators, fans, air conditioners, and other items which rely on AC-powered electric motors. The other common type of inverter (modified sine wave) doesn’t work well for these appliances. When using DC refrigerators, this problem vanishes, as no inverter is needed.
- A Xantrex 2,500 watt modified sine wave inverter/charger.
- Mastervolt AGM 4D batteries, (1) Group 27 AGM battery (710 amp-hours)
While the application is fairly unique, this article is relevant to most people interested in solar power because it specifies important facts that you should know before setting up a solar panel system.
The first fact to know is that the slightest bit of shading significantly affects the power output of solar panels, especially if your solar panels are wired “in series.” The solution is to wire them “in parallel” and, of course, to try to make sure your panels get shaded as infrequently as possible. (On a home, this is done by putting the panels where there isn’t any shade from trees or other objects.)
Since this solar setup is for a boat project, there is the possibility of shading caused by the mast and other parts above the solar panel, so the owners were happy they had learned that lesson from their solar RV projects, but Emily and her husband Mark were still shocked at how much shading affects solar output. There’s a section all about this in their article about the boat.
And, if you’d like a full rundown of how to set up solar in an ideal way on an RV or boat, they also have a multi-part Solar Installation Tutorial for RVers and sailors.
Mark and Emily added several notes about the project, as well as a ton of pictures. Some of the notes are below.
(1) Our odd collection of panels on the Hitchhiker was due to the Kyocera 130 panels not being available at the time of our installation (we brought one over from the Lynx). (2) Our switch from the Outback to the Xantrex charge controllers between the Hitchhiker and the boat was due to the Xantrex being cooled by non-moving fins rather than a fan. In hindsight I would probably use the Outback charge controller in the future only because it displays more information on its screen rather than having to scroll through multiple screens to get the voltage, amperage, watts and charging stage. (3) Our Group 27 start battery on the boat is isolated from the set of 4D house batteries only when the voltage of the bank drops too low.
Combined, the DC refrigerator and DC freezer draw about 100 to 120 Ah (Amp-hours) of current per day. Solar panels generate DC, and batteries supply DC as well. DC refrigerators can be powered without inverters for this reason. This can save plenty of money, which is why solar lights always contain DC LEDs.
Assuming this is a 24 volt system, the refrigerators consume 2.4 kWh to 3.1 kWh per day. (To calculate power consumption in Wh, multiple the voltage by Ah figure.)
In full sunlight, the solar panels generate 22.5 amps. When one panel was partly shaded, they generated 15.5 amps, and when two panels were slightly shaded, they generated 9.5 amps. In the winter, the system generated about 170 amp-hours a day, while it generated about 250 amp-hours a day in summer. With a typical daily amperage use of about 180–250, the duo concluded in retrospect that they should have gone with a more powerful setup.
“In December, around the winter solstice, on the southern mainland of Mexico (Zihuatanejo) our solar setup collected about 170 amp-hours per day. In June, around the summer solstice, in the middle of the Sea of Cortez (San Carlos) our solar setup collected about 250 amp-hours per day. In hindsight, it would be nice to have at least 750 watts of solar power to meet our power demands in winter.”
Again, to check out a lot more about this project, head on over to Road Less Traveled.