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.

No location selected yet — search an address or click the map above.

Step 2 — Refine for Your Panel Angle (optional)

The result above uses your location's standard reference angles. Enter your actual roof tilt and panel direction here for a more precise plane-of-array figure — leave both blank to keep the default.
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🔵 Compare a Second Location

Your Results

Primary Location
Peak Sun Hours
—
avg. hours/day, annual
GHI
—
kWh/m²/day, annual avg
DNI
—
kWh/m²/day, annual avg
At Your Panel Angle
—
enter tilt/azimuth above
Data source: —
Monthly Average Irradiance (GHI)

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.

Monthly average solar irradiance chart.

Results are for reference and estimation only. Verify all values before making any siting or installation decision. See full disclaimer below.

How to Use the Solar Irradiance by ZIP Code Tool

Find Your Location
Type your address or ZIP code, or click the map to drop a pin. Toggle Satellite view or the Day/Night overlay to see current sun exposure at a glance.
Review Your Irradiance Data
Your annual and month-by-month average GHI, DNI, and equivalent peak sun hours appear automatically — no extra inputs required.
Refine or Compare (Optional)
Enter your real panel tilt and azimuth for a more precise plane-of-array figure, and add a second location to see two places side by side. Use Print to capture results as they appear on screen.

Solar Irradiance Terms Guide

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.

🔗 Related Tools

📐 Know your irradiance — now size your system? Use the Solar Panel Size Calculator.
📐 Want the mathematically optimal angle for your location? Try the Optimal Tilt Angle Calculator.
💰 Curious what this irradiance actually means for your wallet? See the Solar Savings Calculator.
🔋 Considering battery backup? Use the Solar Battery Storage Calculator.