Solar Panel Power Output Calculator

Power Output Formula:

\[ P_{out} = P_{rated} \times \left(\frac{G}{1000}\right) \times \left(1 - k \times (T - 25)\right) \]

Rated Power (P_rated):

watts

Irradiance (G):

W/m²

Temp. Coefficient (k):

%/°C

Temperature (T):

°C

Power Output (P_out): watts

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1. What is a Solar Panel Power Output Calculator?

Definition: This calculator estimates the actual power output of a solar panel based on its rated power, current irradiance, temperature coefficient, and operating temperature.

Purpose: It helps solar installers, engineers, and homeowners understand real-world performance of solar panels under specific conditions.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ P_{out} = P_{rated} \times \left(\frac{G}{1000}\right) \times \left(1 - k \times (T - 25)\right) \]

Where:

\( P_{out} \) — Actual power output (watts)
\( P_{rated} \) — Rated power under STC (watts)
\( G \) — Solar irradiance (W/m²)
\( k \) — Temperature coefficient (%/°C)
\( T \) — Panel temperature (°C)

Explanation: The formula adjusts rated power for current sunlight conditions and temperature effects on panel efficiency.

3. Importance of Accurate Power Calculation

Details: Proper output estimation ensures correct system sizing, energy production forecasts, and financial return calculations.

4. Using the Calculator

Tips: Enter the panel's rated power, current irradiance (default 1000 W/m²), temperature coefficient (default 0.45%/°C), and operating temperature (default 25°C).

5. Frequently Asked Questions (FAQ)

Q1: What is standard test condition (STC) irradiance?
A: STC uses 1000 W/m² irradiance at 25°C cell temperature with AM1.5 spectrum - the standard rating condition for solar panels.

Q2: How does temperature affect output?
A: Most panels lose about 0.3-0.5% efficiency per °C above 25°C due to semiconductor properties.

Q3: Where do I find the temperature coefficient?
A: It's listed in panel specifications - typically 0.3%/°C to 0.5%/°C for crystalline silicon panels.

Q4: What's typical real-world irradiance?
A: Peak irradiance is about 1000 W/m² at noon, but varies by location, weather, and season.

Q5: Why is 25°C used as reference?
A: It's the standard test temperature for rating panel performance under STC conditions.