Solar Modules-to Convert Light From The Sun Into Electricity

By Author: Mark C. Robinson
Total Articles: 2
Comment this article

Photovoltaic (PV) solar panels use solar cells to convert light from the sun directly into electricity. At Innovative Solar Solutions, we carry and stock most of the major brands, including Sharp Solar, Kyocera Solar, BP Solar, Evergreen Solar, SolarWorld, Kaneka, Uni-Solar, Suntech , Sanyo, Day4 and OEM Solar modules.

The three most common types of solar panels are Monocrystalline, Polycrystalline, and Amorphous:

Monocrystalline - made from a single large crystal, cut from ingots. Most efficient, but also the most expensive. Somewhat better in low light conditions.

Polycrystalline - cast blocks of silicon which may contain many small crystals, the most common type right now. Slightly less efficient than single crystal, but once set into a frame with 35 or so other cells, the actual difference in watts per square foot is not much.

Amorphous (also called thin film) - the silicon is spread directly on large plates or flexible laminates.They are cheaper to produce, but often much less efficient, which means larger panels for the same power. Uni-Solar is one example.

The differences between ...
... the two module types - crystalline and amorphous- really show up in their sunlight-to-electricity conversion efficiencies and power densities. Crystalline modules require less space than thin-film modules for the same amount of power—thin-film is less efficient in the conversion of sunlight to electricity.

Single- and multicrystalline modules have typical conversion efficiencies between 12% and 17%. But thin-film technologies can have half that, ranging from 6% to 8%. Thinfilm modules take up about twice as much space to generate an equivalent amount of energy compared to crystalline
modules.

Besides power density, there are two key differences in performance between crystalline and thin-film technologies. The first is impact of cell temperature on power production. The second is initial module power stabilization.

All PV modules experience a reduction in power with increasing cell temperature. For example, at 100°F, our sample crystalline module will produce approximately 6% less power than its STC rating. This effect is less pronounced for thin-film PV technologies—our example a-Si thin-film module would produce only 2% less power. While you can reduce cell temperature by allowing adequate air flow around any module, PV cells sitting out in the sun will still get hot—so thin-film a-Si modules might be a good choice for warm climates, especially if there's plenty of room for the larger array.

Amorphous silicon modules take 6 to 12 months to reach their stable, rated output, whereas crystalline modules stabilize right away. So a-Si modules will show 20% to 25% higher-than-rated production at first. While that sounds like a bonus, this initial additional output must be considered in system design (for selecting wire sizes, charge controllers, and inverters). For example, if the final design indicates a 15 A circuit, the initial extra output might require accommodating 20 A. After this stabilization, thin-film modules degrade at similar rates to crystalline, about 0.5% to 1.0% per year.