Sixteen years ago, I installed solar panels on my boat. At the time, the peak efficiency at converting sunlight to electricity was around 16%. Today’s panel technologies enable substantially more energy to be harvested from a given surface area, boosting efficiency as high as 24%—a 50% increase. Taken with other advances, notably how panel output is managed, we have a qualitative improvement in the benefits solar can bring to a boat’s energy systems.
Traditional Panel Technologies
One thing that hasn’t changed is the use of one of three silicon-based technologies: monocrystalline, polycrystalline, and thin-film.
Monocrystalline cells are created by placing a silicon crystal “seed” in a vat of molten silicon and then slowly withdrawing the seed. The molten silicon forms a solid single crystal cylinder around the seed. The cylinder is squared off and sliced into wafers—the basic building block of a cell. A fair amount of the silicon cylinder becomes waste, driving up the cost.
Polycrystalline (multicrystalline) cells also start as a seed in a vat of molten silicon. Once cooled and hardened, the resulting square-sided multicrystal solid is sliced into wafers. Compared with cylindrical, monocrystalline ingots, the square-sided ingots reduce waste and are significantly cheaper.
In theory, a monocrystalline cell is more efficient at converting sunlight into electrical energy than a polycrystalline cell. In practice, enough factors come into play that a high-grade polycrystalline cell in a well-built panel will be more efficient, and sustain that efficiency longer, than a low-grade monocrystalline cell in
