It can be complicated to purchase a panel. You may also find it difficult to understand the specifications. There are many numbers, industry standards and other information on a sheet of specifications for solar panels. These standards and numbers are not applicable to the average consumer. It is important that you understand how solar panels operate before you make a decision about which one to buy.
It is important to know two types of ratings. The STC rating, the first, is important. This is a test that determines the maximum power output the panel can produce under standard test conditions. Under STC test conditions, the cell temperature is 25 degrees Celsius. The test conditions simulate 1,000 W/m2 light. With each degree of temperature rise, the panel's peak rating decreases by a certain percentage. A panel with a higher STC rating is more likely to produce greater power.
PTC Rating is a more recent standard for predicting panel output. It was popularized by the California government, which tested panels. PTC ratings are used mostly for real-world temperatures. It was initially hard to calculate the PTC ratings. California's government improved the process and can now forecast output more accurately. In most cases, the difference between the nominal and rated power is 6%. However, some panels will have negative power tolerances.
Another important feature is the short circuit current. This is the maximum current the panel can output when the cell short circuits. You can measure this by touching the wires together. It is important to have this feature because it assures panel safety. The maximum current is measured as 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 known to be the current at its maximum power point. The nominal power is the voltage at which the maximum power point is reached. 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 maximum power point is lower than the nominal power, the panel will be unable to produce as much power as it could at its maximum power point.
Also important is the panel's efficiency. The efficiency of the solar panel refers to the amount of light irradiance the panel receives. The efficiency is usually expressed in W/m2. The panel absorbs light more efficiently.
Solar panels can also withstand high winds. Panels can support loads up to 5,000 pascals. This is equal to about 2-4 feet of snow. The snow type and density will determine the snow rating. The majority of panels come with a warranty of at most ten years. The warranty will also indicate how long the manufacturer expects the panel to perform. If the company closes down or ceases production, the warranty is null.