A solar module is a photovoltaic device, which means “relating to the production of electric current at the junction of two substances exposed to light.” It is designed to absorb the sun’s rays and utilize them as a source of energy for generating electricity. A solar module (panel) is an arrangement of solar cells that are connected electrically, laminated, encapsulated and packaged into a frame. The common name for this type of device is a “solar panel”. Most home solar panels house 60 cells, although 72 cell solar panels are popular as well. Solar panels are rated by the DC (direct current) output of the device at standard test conditions.
Output ratings have been climbing over the years. Ten years ago, most panels were in the 175-200 watt range, while nowadays panels are in the 250-280 watt range. High efficency panels come in upwards of 300 watts. It is important to consider that panels rated at standard test conditions do not always perform the same in real world conditions. The California Energy Commission (CEC) has published data which shows the results of panels tested in field conditions. We use this data when selecting panels for your system to ensure maximum performance and efficiency.
Solar panels are available in three major types:
Monocrystalline modules are slightly more expensive and slightly more efficient due to the purity of the silicon used in production. They are identifiable by the distinct octagon shapes visible on the surface of the panel.
Polycrystalline modules have square corners and appear to be uniform in color (blue), although some cells may be darker toned.
High Efficiency Panels
As a rule of thumb, 100 square feet of roof space is required for every 1000 watts of photovoltaic modules. High efficiency modules bring this number down to 80 square feet, using 20% less roof space to produce the same amount of power. In other words, high efficiency modules are 20% more powerful.
However, the increase in power per square foot comes at a premium. High Efficiency panels can cost up to 50% more than Standard Efficiency panels for the same amount of power. In addition, the higher voltages associated with High Efficiency panels can make inverter selection more complicated and costly.