Solar Cell Calculator
Calculate solar panel power output, conversion efficiency, fill factor, and daily energy production. Analyze solar cell performance under different conditions.
How do I calculate solar panel power output?
Solar panel power output is calculated using P = V × I, where P is power in watts, V is voltage in volts, and I is current in amperes. Actual output depends on sunlight intensity, temperature, angle, and panel efficiency.
What is solar panel efficiency?
Solar panel efficiency is the percentage of sunlight energy converted to electrical energy. Calculated as Efficiency = (Pmax / (Area × Irradiance)) × 100%. Typical silicon panels are 15-22% efficient, while high-end panels reach 22-26%.
What is the fill factor?
Fill factor (FF) measures solar cell quality: FF = (Vmp × Imp) / (Voc × Isc), where Vmp and Imp are maximum power point values, Voc is open-circuit voltage, and Isc is short-circuit current. Good panels have FF of 0.75-0.85.
What is maximum power point (MPP)?
MPP is the operating point where solar panel produces maximum power. It's not at maximum voltage or current, but at an optimal combination. MPPT (Maximum Power Point Tracking) controllers automatically find and maintain this point for best efficiency.
How does temperature affect solar panels?
Higher temperatures reduce solar panel efficiency and voltage. Voltage typically drops ~0.3-0.5% per °C above 25°C. Power output decreases ~0.4-0.5% per °C. Panels perform best in cool, sunny conditions.
What is solar irradiance?
Solar irradiance is the power of sunlight per unit area, measured in W/m². Standard test conditions use 1000 W/m² (peak sun). Real-world conditions vary: 1000 W/m² (clear noon), 500 W/m² (cloudy), 100 W/m² (heavy overcast).
How do I size a solar panel system?
Calculate daily energy needs (Wh/day), divide by peak sun hours (typically 4-6 hours/day), and add 25% safety margin. For example, 2000Wh/day ÷ 5 hours × 1.25 = 500W of panels needed.
What is the difference between Voc and Vmp?
Voc (open-circuit voltage) is maximum voltage with no load, typically 20-24V for 12V panels. Vmp (maximum power voltage) is the operating voltage at peak power, typically 17-18V for 12V panels. Vmp is used for actual power calculations.
Can I connect solar panels in series or parallel?
Yes. Series increases voltage (V_total = V1 + V2), parallel increases current (I_total = I1 + I2). Series is common for higher voltage systems. Always use matching panels and consider shading effects with bypass diodes.
What reduces solar panel efficiency?
Efficiency is reduced by: high temperatures, partial shading, dirt/dust, wrong angle/orientation, aging, internal resistance, cloud cover, and operating away from MPP. Regular cleaning and proper installation maximize output.
How long do solar panels last?
Quality solar panels last 25-30+ years with minimal maintenance. They typically degrade ~0.5-0.8% per year, retaining 80-85% of original power after 25 years. No moving parts means high reliability and low maintenance.
What is conversion efficiency vs system efficiency?
Conversion efficiency is the panel's ability to convert sunlight to DC electricity (15-26%). System efficiency includes all losses: inverter (95%), wiring (98%), temperature (90%), dirt (95%), giving overall system efficiency of ~75-85% of panel rating.