Buying a solar panel can be a confusing process. The specifications for a panel can be confusing, too. On a specification sheet for a solar panel, there are many numbers as well as industry standards. These numbers and industry standards aren't relevant to the average customer. You should understand the workings of solar panels before you decide on which one you want.
Two types of ratings are important to understand. The STC rating is first. This test measures the panel's maximum power output under standard conditions. The cell temperature must be 25 degrees Celsius under STC conditions. The test conditions simulate 1,000 W/m2 light. For every degree of temperature increase, the panel's peak rating drops by a percentage. A panel that has a higher STC rating will generate more power.
PTC rating, a new standard to predict panel output, is now available. It gained popularity when the California government tested panels. The PTC rating is used mainly for real-world temperatures. Calculating the PTC rating was initially difficult. California's government has improved the process to allow for more accurate forecasting. The difference between the nominal power and the rated power is typically 6%. However, some panels might have negative power tolerances.
The short circuit current is an important specification. This is the maximum amount of current the panel will output if the cell shorts. It is done by touching both wires together. This feature is vital because it makes sure that the panel is safe to be used. The maximum current is measured using watts. If a panel has been wired in series, its maximum output wattage will be the exact same as if wired in parallel.
Another important solar panel specification is the voltage at the maximum power point. This is also called the current at maximum power point. The nominal power is typically equal to what the voltage is at the maximum power. The maximum power point voltage will vary depending on the amount and type of sunlight. The output of a solar panel will be higher if the maximum power point voltage is higher. If the panel's maximum output is lower that its nominal power, it won't be able produce as much power.
It is important to consider the efficiency of your solar panel. The efficiency of the solar panel refers to the amount of light irradiance the panel receives. The efficiency is often expressed in W/m2. The panel absorbs more light if it has a higher efficiency.
Solar panels can also be rated for resistance to wind pressure. The panel can carry a load of approximately 5,000 pascals. This is about 2 to 3 feet of snow. The snow type and its density influence the amount of snow that can be rated. It's important to remember that most panels have a warranty of at least ten years. The warranty will also indicate how long the manufacturer expects the panel to perform. If the company goes out business or discontinues production of the panel, the warranty becomes null.