What are peak sun hours?

Peak sun hours (PSH) represent the number of hours per day during which solar irradiance averages 1,000 W/m² (1 kW/m²). This is not the same as daylight hours. A location with 5 PSH receives the same total solar energy as 5 hours of full-strength noon sun. Typical values range from 2.5 PSH (cloudy climates) to 7 PSH (desert regions).

What is a typical system loss factor?

A combined system loss of 14–20% is standard. This accounts for inverter efficiency (~96%), wiring resistance (~2%), temperature derating (~5%), soiling (~2%), and mismatch losses (~2%). A clean, well-maintained system in a cool climate can achieve losses as low as 10%, while a hot, dusty environment may see 25% or more.

How does tilt angle affect output?

Tilt angle affects how directly sunlight strikes the panel surface. The optimal tilt angle is approximately equal to your latitude for year-round production. Tilting toward the equator at the right angle maximizes irradiance. This calculator applies a cosine-based tilt correction factor relative to a horizontal surface receiving peak sun hours data.

What panel efficiency should I use?

Standard polycrystalline panels run 15–17% efficiency. Monocrystalline panels typically achieve 18–22%. Premium high-efficiency panels (e.g., SunPower, REC Alpha) reach 22–23%. The efficiency is already encoded in rated panel wattage per m², so if you enter both panel area and wattage, the calculator derives efficiency automatically.

What is the difference between DC and AC output?

DC output is what the solar panels generate directly. AC output is the usable power after the inverter converts DC to AC electricity for home use. The difference represents inverter losses, typically 3–5%. Grid-tied systems always report AC output as the energy fed to the home or grid.

Solar Irradiance Calculator

Name: Solar Irradiance Calculator
Availability: InStock
Author: Nham Vu

Enter your panel specs, tilt angle, and peak sun hours to instantly calculate solar irradiance and estimated daily energy output.

System Parameters

Panel Wattage (W per panel)

Rated DC power output per panel at STC

Number of Panels

Panel Area (m² per panel)

Typical residential panel: 1.6–2.0 m²

Peak Sun Hours (hours/day)

US average: 4–6 h/day. Tropics: 5–7 h/day

Panel Tilt Angle (°)

0° = flat roof. Optimal ≈ local latitude

System Losses (%) 14%

5% (ideal) 40% (poor)

Fill in your system parameters and click Calculate

Supports any panel size from small rooftop arrays to utility-scale installations

Summary

Enter your panel specs, tilt angle, and peak sun hours to instantly calculate solar irradiance and estimated daily energy output.

How it works

Enter the total panel area or number of panels and wattage per panel.
Set the panel efficiency percentage (typically 15–22% for modern panels).
Input the tilt angle of your panels relative to horizontal.
Enter the average peak sun hours for your location (3–7 hours/day for most regions).
Specify system losses (wiring, inverter, temperature, soiling — typically 10–20%).
The calculator instantly outputs irradiance, DC power, AC power, and daily energy in kWh.

Use cases

Estimate solar panel output before purchasing a residential PV system.
Compare tilt angle configurations to maximize seasonal energy yield.
Size a battery storage system based on expected daily generation.
Validate solar installer proposals with an independent calculation.
Plan off-grid power systems for cabins, boats, or remote sites.
Analyze the impact of panel efficiency on total energy production.
Benchmark different panel models under identical conditions.
Teach students about solar energy fundamentals and PV system design.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu