20 Terms To Help You Understand Solar Panel Specifications
American Manufacturer – A company whose materials are manufactured in America.
Anti-Reflection – Coating applied to the glass of solar panels in order to reduce sunlight reflection and increase the efficiency of the panel.
Back Plate – The outermost layer of the module that protects the internal parts of the cell from outside harm and insulates the cell.
Building Integrated Photovoltaics (BIPV) – Building integrated photovoltaics function both as an external layer of a building and as an energy producing system. Examples of BIPV include solar shingles and solar windows.
Black-on-Black – All black solar panels consisting of a black frame, black cells, and a black backsheet (film substrate on which the cells sit on). This is done for an aesthetic appeal.
Degradation – Gradual reduction of panel power output over time due to corrosion from water vapor, metal ion migration, deterioration of the anti-reflection coating, temperature, UV exposure, and mechanical damage
Frame – Encases backsheet, solar cells, and glass on solar panel.
Monocrystalline – Composed of a single layer of crystalline silicon cells, which allow electrons to move freely around cell and results in slightly more efficient panels. Monocrystalline panels have oval shaped cells and are usually black.
Multicrystalline – Formed by melting multiple layers of crystalline silicon. These are typically cheaper and less efficient than monocrystalline panels.
Nameplate Rating – Indicates the power output of a solar panel under industry standard test conditions. Higher nameplate ratings mean a higher power output from the panel. Ratings typically range between 200 to 360 watts.
Nominal Power – Maximum DC power output of a solar panel under industry standard testing conditions. This is different than the power output under real world conditions, where there are typically losses due to various factors.
Panel / PV Efficiency – The percentage of available sunlight that is able to be converted into electricity by a solar panel. PV panel efficiency now lies anywhere between 15-22%.
Peak Watts – Maximum possible power output under standard testing conditions.
Polycrystalline – Composed of fragmented silicon melted together to form multicrystalline cells. They are slightly less efficient than monocrystalline panels, typically are blue in color, and have rectangular shaped cells. They are typically sold at a slightly lower price point.
Power Rating – The amount of power produced under ideal standard testing conditions.
Premier Panels – Tier-one, high-efficiency modules produced by well-known, name-brand manufacturers, usually at a higher price point. Examples would be LG, Panasonic, and Sunpower.
PTC – Testing conditions developed by the National Renewable Energy Laboratory to simulate real world conditions. The temperature of the solar cells is set to 45 degrees Celsius to simulate heating from sunlight. Ambient temperature is 20 degrees Celsius with winds of 2.2 mph. As internal temperature rises in solar cells, the panel power output drops in comparison to standard testing conditions in a lab.
Single-Crystal Structure – The molecular lattice of the crystal is linear and unbroken, making a continuous, uniform structure.
Solar Shingles (or Tiles) – Solar photovoltaic modules designed to look and function as roofing shingles while simultaneously producing electricity.
Standard Testing Conditions (STC) – Used for uniformity in comparisons of panels in a laboratory environment. Under STC: irradiation = 1000 W/m², temperature = 25°C, AM = 1.5 (air mass).
Temperature Coefficient – Temperature coefficient indicates what percentage of the panel’s power output will drop by for every degree above 25 degrees Celsius (ex -0.52%).
Thin-Film Solar Panels – Solar panels made with thin layers of material placed on a glass, plastic, or metal substrate. These are typically the cheapest and least efficient of all panel types.