Solar power comes in a variety of different forms, from solar water heating to the seemingly paradoxical solar cooling. In recent years, however, photovoltaic solar systems have emerged as the most popular type of residential solar installation. Photovoltaic panels, which convert sunlight directly into electricity through something called the photoelectric effect, mostly fall into two categories: crystalline silicon solar panels and thin-film solar panels.
Crystalline silicon is the traditional solar panel that most people are familiar with. The National Renewable Energy Laboratory explains that the active material that actually converts light in these panels is a layer of silicon a few hundred micrometers in thickness. While that might seem thin, it still makes these panels relatively inflexible, requiring manufacturers to encase the the material in sturdy glass.
In addition to high prices for silicon, concerns about extensive needs for high-quality glass were one of the main incentives behind investment in thin-film solar panels in the 1980s, according to EnergyBoom. This younger technology uses a much smaller layer of the active photoelectric material, layered over either thin glass or metal with a similarly thin protective layer above. The active material, often amorphous or non-crystalline silicon, generally only measures about one micrometer thick, bringing material costs for thin-film solar panels down dramatically.
Since their inception, thin-film technology has reached a number of important thresholds in the solar industry, including bringing manufacturing costs per watt below $1 for the first time. The primary problem for the thin-film technology is that using so little photoelectric material substantially reduces how much of the sunlight striking a solar panel gets transformed into electricity. According to CivicSolar, crystalline silicon solar panels generally range between 13 and 19 percent efficiency, but thin-film panels only reach around 12 percent efficiency and can go as low as 4 percent. However, numbers for both technologies have climbed steadily as investment in the industry has increased.
Solar industry group Solarbuzz notes that, despite growth within the thin-film industry, crystalline silicon still holds 80 to 90 percent of the photovoltaic solar panel market. EnergyBoom cites a report by GreenTech Media from 2010 suggesting that declining costs for silicon could prevent thin-film technology from emerging as the dominant technology.
Recently, concentrating solar systems have emerged as an increasingly popular approach to increasing the efficiency of solar panels. However, these systems of mirrors and lenses designed to focus more light on fewer panels generally require active tracking systems and are better suited to large scale solar plants.
Ultimately, most residential solar installers will choose between thin-film and crystalline silicon solar panels. If space is not an issue, thin-film solar panels can provide a cheaper option. Smaller solar installations will likely get more use from crystalline silicon panels, but the decision could come down to how many rebates or financing options are available.