A solar panel is a device made from materials that are able to convert photons from the sun into direct current electricity. The ability of certain materials to convert solar radiation from the sun into electricity is known as the photovoltaic effect and solar panels are often referred to as photovoltaic (PV) panels or PV solar panels. Several solar panels connected together are called a photovoltaic array. Common materials that are used to build solar panels are crystalline silicone and copper indium selenide.
How is a Solar Panel Output Rated
The power output rating of a solar panel is rated in watts of power. The amount of watts of power that a particular solar panel will produce must be calculated by how many peak sun hours (insolation) the solar panel will be exposed to. A solar panel's watt hours will, therefore, depend on its location or exposure to direct sunlight. For solar panel system installations that are permanently exposed to the weather then the peak sun hours will be determined by the geographical location of the solar panel system. Peak sun hours are the number of hours of sun hours per day that are of peak benefit to solar panels.
How Do I calculate sun hours?
Different parts of a country and different countries have different insolation levels or sun hours. The power output of a solar panel, or solar watt hour, with a rating of 20W would be calculated by multiplying 20 by the number of peak hours of sunshine, for example 4 hours and then multiplying the result by 0.85. So, a 20W solar panel exposed to 4 hours of peak sunlight per day will produce 68 watt hours. Usable output of solar panels can not, by themselves, power such things as televisions because a stable power source is required. Normally, such requirements from solar panel systems involve the inclusion of banks of batteries that are recharged by the solar panels and feed the appliances.
How Are Watt Hours Calculated?
Thankfully, when designing a solar panel system for residential or commercial purposes the sun hours need not be calculated by sitting in the sun and counting how many hours of usable light will be available to a solar panel. The number of sun hours available in most locations, are readily available online in what are called 'solar insulation charts'. Solar panel designers will use insolation values to determine the necessary output watt rating of solar panel systems installed in a particular location based upon the areas insolation value as well as the load that will be connected to the system.