Last week, we posted a little primer on the overall makeup of a solar energy system. That, of course, is only the beginning. Every specific category on that list, from panels to batteries, represents a complex segment of the system that requires serious research before buying. This in mind, we’ll be covering each of these links one by one, to give a more complete understanding of both the science involved, and what to look for when purchasing the implements correct for your purposes.
Solar panels are primarily based in silicon, a highly conductive element that generates electrical current when exposed to light. Composed of units called “cells,” each of which is a 36-square-inch piece of silicon, solar panels are made by laying out a grid of cells, with a protective sheet on the rear and glass on the front. A collection of such panels is termed an “array.” When wired into the same inverter however, they are known as a “string.” This is important because each inverter will have a maximum “string” size it can support, meaning a maximum number of panels it can have in its system.
There are two standard configurations for solar panels: 60-cell or 72-cell. The only real difference between these two is that 72-cells are about a foot taller, thanks to the extra 12 cells. While other sizes do exist, these are the main you’ll see for at-home use. Cells are either monocrystalline or polycrystalline–monos are cut from a single source of silicon, whereas polies come from multiple. This makes mono cells slightly more efficient.
Solar panel energy is measured in terms of efficiency rating, which sounds confusing to some. For instance, a 20-percent efficiency rating does NOT mean that your solar panel is only producing at 20-percent capacity, but that it is converting only 20-percent of the energy coming from the sun. A common explanatory example is, if the sun is producing 500-watts, and you have a 100-watt panel, this panel is producing at 20-percent efficiency. Thus efficiency really only matters in terms of space–the more efficient panels, the less/smaller surface area of them you’ll need.
While on the topic though, solar panels are rated according to how much Direct Current (DC) power they produce. This is measured in “wattage,” with the wattage rating referring to how much power the panel produces in an hour. A 300-watt panel, for instance, will produce 300-watts an hour under optimal solar conditions. In terms of size, if you have a 300- and a 400-watt solar panel, both with an efficiency rating of 20 percent, the 400 watt will be physically larger. If the 400 watt panel has a 25-percent efficiency rating however, they should be closer to the same size.
This should be enough to get ya’ll going on solar panels. Tune in to our next solar-panel-project installment, for more on the next link in our system: combiner boxes.
A humble homesteader based in an undisclosed location, Lars Drecker splits his time between tending his little slice of self-sustaining heaven, and bothering his neighbors to do his work for him. This is mainly the fault of a debilitating predilection for fishing, hunting, camping and all other things outdoors. When not engaged in any of the above activities, you can normally find him broken down on the side of the road, in some piece of junk he just “fixed-up.”