Solar panel wattage, or rated power capacity, measures the maximum electrical power output a panel produces under standard test conditions. Expressed in watts (W) or kilowatts (kW), this rating indicates the panel’s peak performance potential. Residential panels typically range from 300W to 400W per unit.
Technical Details
Wattage is determined under Standard Test Conditions: 1,000 W/m² solar irradiance, 25°C cell temperature, and Air Mass 1.5 spectrum. Real-world output varies based on weather, temperature, time of day, and installation angle. A 350W panel rarely produces its full rated output except under ideal midday conditions on clear days. The total system wattage equals the sum of all individual panel wattages.
Practical Significance
Panel wattage directly affects system cost and space requirements. A 10kW system might use 25 to 30 panels of 350W capacity. Higher wattage panels reduce installation complexity and required roof area. Understanding wattage ratings helps homeowners estimate annual energy production and system sizing for their specific electricity needs.