Solar Panels Overview
Solar cells are typically named after the semiconducting material they are made of. These materials must have certain characteristics in order to absorb sunlight. Some cells are designed to handle sunlight that reaches the Earth's surface, while others are optimized for use in space. Solar cells can be made of only one single layer of light-absorbing material (single-junction) or use multiple physical configurations (multi-junctions) to take advantage of various absorption and charge separation mechanisms.
As of 2017, a typical solar panel produces around 265 watts of power. That can vary based the size and efficiency of the solar panel you choose; you’ll see panels that produce 210, 280, even 320 watts. More efficient panels are a little more expensive, and are usually only needed if you have limited space on your roof. Your solar installer will work with you to figure out how many panels you need to produce enough energy for you to use. It generally matters less how much each panel can produce than how well the whole array performs.
Solar panel conversion efficiency, typically in the 20% range, is reduced by dust, grime, pollen, and other particulates that accumulate on the solar panel. "A dirty solar panel can reduce its power capabilities by up to 30% in high dust/pollen or desert areas", says Seamus Curran, associate professor of physics at the University of Houston and director of the Institute for NanoEnergy, which specializes in the design, engineering, and assembly of nanostructures.