Solar panel wattage is the total amount of power the solar panel can produce in a given time. It is usually measured in watts and calculated by multiplying the solar panel’s voltage, amperage, and the number of cells. The typical solar panel power rating varies between 40 and 480 watts.
Today, most silicon-based solar cells can convert approximately 18 to 22 percent of the sunlight they receive into usable solar energy. This advancement has led to solar panels exceeding 400 watts in power output. In simple terms, higher efficiency equals more energy production.
The 60-cell panels typically measure around 5.4 feet in height and 3.25 feet in width. The output capacity of these panels ranges from approximately 270 to 300 watts. In contrast, 72-cell solar panels are larger because they include an extra row of solar cells. This can result in an average power output of about 350 to 400 watts.
The solar panel output rating of the average residential panel is between 250 and 485 watts, but commercial modules can have a higher solar panel rating. For example, Trina Solar's ts n-type i-TOPCon solar module for applications in large-scale PV projects can have an output of up to 740 watts.
Real-world conditions rarely achieve STC consistently, so actual efficiency is typically lower than the lab ratings. The key metric used to measure solar panel efficiency is “rated watts.” A 250-watt solar panel with 18% efficiency under STC can be expected to produce around 250 watts of usable AC power under ideal conditions.
Recent top efficiency solar cell results are given in the page Solar Cell Efficiency Results. η is the efficiency. The input power for efficiency calculations is 1 kW/m 2 or 100 mW/cm 2. Thus the input power for a 100 × 100 mm 2 cell is 10 W and for a 156 × 156 mm 2 cell is 24.3 W