Find your location below — results appear automatically, no extra inputs required. Panel angle and location comparison are both optional.
Step 1 — Find Your Location
Type your address or ZIP code, or click the map to drop a pin.
Or use the map: click anywhere to drop a pin, then tap "Use This Location" to confirm.
Map isn't available right now — try refreshing, or search by address/ZIP above instead.
Step 2 — Refine for Your Panel Angle (optional)
Or use this map: click to drop a pin.
Your Results
Your location's average solar irradiance for each month of the year, in kWh/m²/day. A comparison location, if added, appears as a second set of bars.
Results are for reference and estimation only. Verify all values before making any siting or installation decision. See full disclaimer below.
Solar irradiance data uses a handful of terms most calculators don't explain. Here's what each one in your results actually means.
Solar Irradiance vs. Solar Insolation
Irradiance is an instantaneous measurement — the power hitting a surface at a given moment, in watts per square meter. Insolation is cumulative — the total energy received over a period like a day or year, in kilowatt-hours per square meter. In practice, and on this page, the two terms are often used interchangeably, the way "speed" and "distance traveled" describe related but distinct things.
Peak Sun Hours
One peak sun hour equals one hour of sunlight at a full-intensity 1,000 W/m². A location averaging 5 kWh/m²/day of GHI is described as getting 5 peak sun hours per day — the same number, expressed in a way that's easier to reason about than a raw energy unit.
GHI (Global Horizontal Irradiance)
Total sunlight reaching a flat, horizontal surface — direct sunlight plus the portion scattered by the atmosphere. This is the number most directly relevant to a typical fixed-tilt rooftop system.
DNI (Direct Normal Irradiance)
Only the sunlight arriving in a straight line from the sun, measured on a surface held perpendicular to it — which in practice means a surface that tracks the sun's position. More relevant to concentrating solar or tracking systems than most home installations.
Plane-of-Array Irradiance (Your Panel Angle)
The irradiance your panels would actually receive at their real tilt and compass direction, rather than the flat-horizontal (GHI) or latitude-tilt reference values. This is what Step 2 calculates once you enter your real tilt and azimuth.
This guide is provided for educational and reference purposes.