PV Solar Panel Output Calculator

PV Solar Panel Output Calculator

Wiratama

11/16/20251 min read

1. Definition

A PV (photovoltaic) solar panel output calculator estimates the electrical power and energy a solar panel can produce under real operating conditions. It accounts for factors such as:

  • Solar irradiance

  • Panel efficiency and rated power

  • Temperature effects

  • Derating factors (wiring, inverter, dust, aging)

  • Peak sun hours

This tool helps engineers, installers, and homeowners estimate daily, monthly, and annual solar energy production for system sizing and feasibility studies.

2. Background Theory

2.1 Standard Test Conditions (STC)

Solar panels are rated at STC:

  • Irradiance: 1000 W/m²

  • Panel temperature: 25°C

  • Air mass: AM 1.5

Actual field conditions differ, so corrections are needed.

2.2 Irradiance Effect

Solar power output is proportional to irradiance:

P~ G

Where:

  • G = irradiance in kW/m²
    (Usually 0.5–1.0 kW/m² depending on sunlight intensity.)

2.3 Temperature Effect on Panels

Panels produce less power at higher temperatures. This is modeled using the temperature coefficient:

Where:

  • β\betaβ = temperature coefficient (%/°C)

  • TTT = actual panel temperature

  • Higher temperature → lower output

Typical β=−0.3% to -0.5%/°C.

2.4 Derating Factor

Real systems lose power due to:

  • Inverter losses

  • Dust and dirt

  • Cable resistance

  • Shading

  • Aging

Typical derating is 70–90%.
This calculator uses:

Pactual=Pcorrected×(derate)

2.5 Energy Output

Daily energy is:

Eday=Pactual×Peak Sun Hours

Then:

Emonth=Eday×30

Eyear=Eday×365

Peak sun hours (PSH) vary by location (3–6 hr/day typical).

3. How the Calculator Works

Step 1 — User Inputs

You enter:

  • Panel rated power (Wp)

  • Irradiance

  • Panel area

  • Temperature coefficient

  • Actual panel temperature

  • System derating factor

  • Peak sun hours

Step 2 — Irradiance & Temperature Correction

The calculator adjusts the panel’s rated output based on actual irradiance and temperature.

Step 3 — Apply Derating Factor

All system losses are condensed into a single efficiency multiplier.

Step 4 — Compute Power Output

The calculator produces:

  • Corrected DC Power (kW)

Step 5 — Compute Energy Production

It then estimates:

  • Daily energy output (kWh/day)

  • Monthly energy output (kWh/month)

  • Yearly energy output (kWh/year)

These results are ideal for quick PV system sizing or comparison of panel performance.

Applications

This calculator is useful for:

  • Solar PV feasibility and planning

  • Residential and commercial solar sizing

  • Engineering coursework and design projects

  • Comparing different PV modules

  • Quick rooftop estimates