Photovoltaic (PV) panels are critical for any solar roof system. Solar panels vary in many aspects. Major considerations for solar panel are technology, efficiency, wattage and amp output, size, price and brand. There are many brands available for solar panels too. Below is a quick overview of commercial available PV panels.
Technology: common types of solar panels are Monocrystalline, Polycrystalline, Amorphous, cadmium telluride, etc. When solar cells are cut from a chunk of silicon that has been grown from a single crystal, they are moncrystalline cells. In comparison, polycrystalline cells are cut from multifaceted silicon crystals. More surface area is related to inherent flaws and thus polycrystalline is less efficient and less expensive than monocrystalline cells. Amorphous silicons are non-crystalline form of silicon. Amorphous solar cells are relatively cheap to produce and widely available.
Efficiency: in general the efficiency of solar panels can range anywhere from 6% to 40%. Efficiency is measured as the electricity energy produced by solar cell compared to the sunlight energy it receives. Usually Monocrystalline cells have highest efficiency and can be as high as 20%. Polycrystalline cells are slightly less efficient than single crystal, but the actual difference in watts per square foot is not much. In comparison, the efficiency of amorphous solar cells is typically between 6-8%.
Wattage rating: solar modules can vary largely in rating. Commercial solar modules can range from 1 watt to about 300 watts. The size and weight of solar modules increase with the wattage rating. Roughly a solar module of 100 watts approximately needs an area of 10 square feet to install.
Size: A 100 watt solar model can weight around 20 lbs. Solar modules over 200 watts can weight 40 lbs. and above. For an average U.S. household need of 3,000 watts, roughly 300 square feet area to place solar panels. Larger area may be needed if considering other factors such as the number of rainy days (Solar Introduction) and the loss of the DC/AC inverter.
Price: Solar panels can vary widely in price. Typical price range is $3 to $6 per watt. Recently low price per watt (such as $1 per watt) solar panels are also available. In addition, tax credits and utility rebates also drive down the cost of solar roof system.
Brands/Solar Companies: There are many companies that make solar panels. Here is a non-exclusive list: ALPS, BP Solar, GE, Sharp, SolarTech, SolarWorld, SANYO, Photon Solar Panels, SolCharger, SunWize Solar, Suntech Solar, Trina Solar and Uni-Solar.
This article is not meant to be a guide for purchasing/installing a solar roof system, rather it provides basics of a solar system and list resources for those who may consider solar as alt. energy source.