klepZ ArrayCare

Solar by state / Oregon

Solar potential
in Oregon.

Daily irradiance4.1kWh/m² average, 3.5–4.5 across the state
Per kW installed1,136kWh a year, south-facing at 0.80 PR
Strongest monthJuly7.4 kWh/m² a day
National rank27 / 51by sampled irradiance

Oregon averages 4.1 kWh per square metre a day across the 8 grid cells sampled inside it — 27th of 51 states by that measure. July is the strongest month at 7.4, December the weakest at 1.2.

What that means for an array

On the same assumptions the ArrayCare check uses — a south-facing array and a 0.80 performance ratio — that works out to roughly 1,136 kWh a year for every kW installed, or 7,952 kWh for a 7 kW system. Irradiance is what arrives; production is what a specific array, at a specific tilt, with specific shading and losses, converts. Those are different numbers and a real quote will use the second.

Where in the state

The spread inside Oregon runs from 3.5 kWh/m²/day around Clatsop County to 4.5 around Harney County — 31% between the dimmest and sunniest sampled cells, or about 298 kWh a year per kW installed. Where in the state a roof sits matters more than the state average does.

How precise this is

These figures come from NASA POWER's solar climatology, a grid of roughly 55 km cells. Two points 40 km apart return the same numbers, which is why this page covers a state and prints the range across 8 sampled cells rather than claiming a figure for a town or a ZIP code. Local terrain, coastal fog and elevation all move the real number at a given address, and none of them are visible at this scale.

Through the year

July runs 6.3× stronger than December. That is an extreme seasonal swing. Winter output is close to negligible, and an annual average badly misdescribes a year shaped like that.

MonthkWh/m² a daykWh per kW installed
January 1.5 34
February 2.4 50
March 3.5 81
April 4.9 110
May 6.0 141
June 6.8 154
July 7.4 173
August 6.3 148
September 4.8 108
October 3.0 71
November 1.7 38
December 1.2 28

Monthly means across the 8 sampled cells. The per-kW column applies a south-facing orientation and a 0.80 performance ratio to the irradiance beside it — the same arithmetic the array check uses.

The cells behind these numbers

Each row is one NASA POWER grid cell, named for the county its sample point falls in. Two counties in the same cell would return the same numbers, so only one of each appears.

Sample pointkWh/m² a daykWh a year per kW
Harney County4.51,250
Deschutes County4.51,244
Josephine County4.51,223
Grant County4.31,187
Sherman County4.21,155
Polk County3.91,065
Multnomah County3.71,008
Clatsop County3.5952

Against the rest of the country

For scale, Arizona leads the country at 5.8 kWh/m²/day and Alaska trails at 2.5. The national spread is narrower than most people expect — the sunniest state is not ten times the dimmest, it is about 2.3×.

Sunlight is only one input into whether solar pays somewhere. Electricity prices, net-metering rules, incentives, roof condition and shading routinely matter more than the difference between two neighbouring states, and none of them are on this page. ArrayCare is independent, sells nothing, and is not a quote.

States with similar sun

All 51 states ranked →