What are peak sun hours?

Peak sun hours (PSH) are equivalent full-sun hours where irradiance equals 1,000 W/m². A location receiving 5 PSH/day receives the same total solar energy as 5 hours of perfect noon-level sun, regardless of actual daylight length.

How does latitude affect solar energy?

Higher latitudes receive sunlight at a lower angle, spreading energy over a larger surface area and reducing irradiance. Locations near the equator (0°) generally receive 5–6 PSH/day year-round, while polar regions may average 2–3 PSH/day.

Why does climate zone matter?

Cloud cover, humidity, and aerosols reduce the sunlight reaching your panels. A desert climate at 30° latitude will receive far more usable solar energy than a coastal or temperate climate at the same latitude with frequent overcast skies.

What tilt angle should I use?

For a fixed-tilt system, the optimal angle is roughly equal to your latitude. Tilting toward the equator at that angle maximizes annual production. In the northern hemisphere, panels face south; in the southern hemisphere, they face north.

How accurate is this estimate?

This tool uses a simplified empirical model suitable for preliminary sizing. For bankable feasibility studies, use NASA POWER, PVGIS, or PVWatts with on-site irradiance measurements. Expect ±10–15% accuracy from this calculator.

How do I calculate how many solar panels I need?

Divide your daily energy need (kWh) by the peak sun hours to get the required array size in kW. Then divide by your panel wattage (e.g. 0.4 kW per 400 W panel). Example: 20 kWh/day ÷ 5 PSH = 4 kW array ÷ 0.4 kW/panel = 10 panels.

Sun Hours by Location

Name: Sun Hours by Location
Availability: InStock
Author: Nham Vu

Enter your latitude and climate zone to get estimated peak sun hours per day for accurate solar panel sizing.

Location Parameters

Latitude (degrees)

Negative = southern hemisphere. Use your city's latitude.

Climate Zone

Panel Tilt Angle (degrees)

Tilt from horizontal. 0° = flat, 90° = vertical.

Daily Energy Need (kWh/day) — optional

Enter to get a panel count estimate.

Panel Wattage (W) — optional

Enter your location parameters and click Calculate.

Summary

Enter your latitude and climate zone to get estimated peak sun hours per day for accurate solar panel sizing.

How it works

Enter your latitude (negative for southern hemisphere, 0–90 range).
Select the climate zone that best describes your region.
Optionally enter a panel tilt angle (defaults to latitude for optimal fixed tilt).
The calculator applies latitude-based irradiance curves adjusted for climate and tilt.
Results show daily peak sun hours, monthly breakdown, and a simple panel sizing guide.

Use cases

Size a residential or commercial solar array for a specific location.
Estimate annual kWh output before purchasing solar panels.
Compare solar potential across different cities or countries.
Determine the number of panels needed to offset a given electricity load.
Quick feasibility check before commissioning a full solar site survey.
Teaching or learning about solar resource assessment.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu