How much will solar panels produce in Portland?

A 8 kWp system facing south at 35° tilt in Portland produces about 10,468 kWh a year. In a weak year that is 8,769 kWh, in a good one 12,167 kWh — 1,309 kWh per kWp.

That’s about 100% of a typical home’s yearly use (10,500 kWh).

Calculate for my roof

Based on 2014–2023 satellite weather data

Production by month

05001,0001,5002,000JanJanuary: 8 kWp 431 kWh, range 298–563FebFebruary: 8 kWp 499 kWh, range 351–648MarMarch: 8 kWp 837 kWh, range 622–1,051AprApril: 8 kWp 1,017 kWh, range 775–1,260MayMay: 8 kWp 1,131 kWh, range 938–1,325JunJune: 8 kWp 1,207 kWh, range 936–1,478JulJuly: 8 kWp 1,368 kWh, range 1,099–1,638AugAugust: 8 kWp 1,329 kWh, range 1,103–1,555SepSeptember: 8 kWp 1,101 kWh, range 894–1,307OctOctober: 8 kWp 781 kWh, range 615–948NovNovember: 8 kWp 481 kWh, range 345–617DecDecember: 8 kWp 314 kWh, range 220–407

kWh per month

A typical day in July

The sunniest month in Portland. Output peaks around 12:00 solar time, at about 5.0 kWh in the best hour.

0:006:0012:0018:0023:00 5.0 0

Month by month

Month Weak year, kWh Typical year, kWh Good year, kWh
January 298 431 563
February 351 499 648
March 622 837 1,051
April 775 1,017 1,260
May 938 1,131 1,325
June 936 1,207 1,478
July 1,099 1,368 1,638
August 1,103 1,329 1,555
September 894 1,101 1,307
October 615 781 948
November 345 481 617
December 220 314 407
Year 8,769 10,468 12,167

The months don’t add up exactly to the yearly figure, because each one is the typical value across many years.

Common questions

How much do solar panels produce in winter in Portland?

From November to February the system produces about 1,725 kWh, which is 16% of the year. The weakest month (December) gives roughly 314 kWh.

Is an east-west roof worth it in Portland?

An east-west system typically produces 10–25% less per kWp than one facing south, but spreads production more evenly through the day. The exact difference depends on tilt and shading.

Compare an east-west roof for Portland

Ground mount or roof in Portland?

A ground mount can be tilted and aimed freely, which can add some yield, but it costs more and needs space. Compare both for your own plot.

Check a ground-mounted system in Portland

Your roof is not an average roof

Set your own tilt, direction, shading and inverter limit and get a range for your address.

Calculate for my roof

All cities in United States

Climate data: Photovoltaic Geographical Information System (PVGIS) — European Commission, Joint Research Centre