Pointing the array squarely with the panels perpendicular to the sun makes a large difference in efficiency as well as does the temperature. This defect is corrected somewhat by the use of bypass diodes across each cell, which allow the module to produce power even when partially shaded. Shading two or more cells effectively turns off the panel until the shadow is removed. Shaded cells show a large voltage drop that acts as a barrier to useful power production, and shading a single cell on a panel can cut its output by 20 percent or more. Shadows covering even a tiny fraction of the panel have a dramatic impact on power output, for crystalline panels only. Using a 225 W solar array to charge my batteries, I only needed to burn seven gallons of diesel fuel on a 2,140-mile race to Kauai. ![]() the amount of time a panel spends in full sun averages four or five hours per day.ġ65-watt rigid monocrystalline panel deployed on the author's Cal 40. Full sun means enough light so you see fairly sharp-edged shadows (most locations get no more than 80 to 85% of full sun). We arrive at these values by averaging the number of hours the panel spends in full sun (defined as 1000 watts of energy per square meter). As they say in the car commercials, “your mileage may vary,” but this rule of thumb works well for estimating a panel’s output. We also use a simplifying assumption, and that is the panel will put out its maximum output for five hours a day. We rate them in Amps, since most boaters have an idea of how many amp-hours their battery capacity is, or how many amp-hours they use in a day while cruising. Panels are measured in either Watts, or Amps, or both. Solar panels charge 12V batteries, and might have a voltage of 20V with no battery in the circuit, but are engineered to provide their power at the voltage a 12V battery requires for full charging. As a clean, renewable energy source, it can save more than 400 million cubic feet of natural gas over the same 30-year period. According to the EPA, a 57.6W solar power system like West Marine's can eliminate 4.4 million pounds of carbon dioxide that would otherwise be produced by a power plant over 30 years. ![]() We constructed our own sizable 57,600W array on the roof of our Santa Cruz, CA, store (with 480 panels of 120W each, connected to 24 inverters, rated at 2,100W each, producing enough electricity to meet 70% of the store's electrical needs). West Marine and Solar PowerĪs part of our company Mission Statement and our commitment through our BlueFuture™ initiative to reduce our impact on the environment, West Marine has embraced photovoltaic technology. Truly efficient solar-equipped boats may not have to use the engine for charging at all. With a couple of solar panels installed, these boats can often extend their time between engine uses by a day or more. Many sailboats that go on long passages have to use their propulsion engine for one to two hours per day to charge batteries and replace the energy that’s been consumed. Since solar panels put out pure DC power, they are excellent chargers as long as they have a regulator in the circuit when they require it (see below).Ĭruising and racing sailboats can use solar panels to augment or replace their other charging sources. All batteries self-discharge, and a small panel can eliminate the problems caused by dead batteries. Small boats: A solar panel can keep the battery fully charged when the boat is on the trailer, at a mooring or sitting at her slip. Basic mechanical tools including wrenches, screwdrivers.Adding a solar trickle charger to your car, RV or boat: 1 out of 10Īdding a flexible panel to charge while underway: 2 out of 10Īdding a permanent panel to the stern railing: 4 out of 10Īdding a charge controller to your installation: 4 out of 10Īdding an electrical system monitor to your boat: 6 out of 10Īdding two panels to a dodger or radar arch: 8 out of 10
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