PVWatts Studio — Official-Model Solar Production Estimates

System Parameters

Start with a location and system size. Valid changes recalculate the estimate automatically after a short pause.

Quick estimate

System location

Enter an address, place, ZIP code, or latitude and longitude.

Renton, WA (47.49100, -122.21600)

Location search © OpenStreetMap contributors

DC system size 4.0 kW

Module type

Array type

Live annual estimate

Calculating with the current inputs…

— kWh/year

Review full results

Orientation & losses

System losses 14.08 %

Array tilt 20°

Array azimuth 180° (South)

Compass Azimuth

180° south

Roof Tilt Angle

20° tilt

Advanced model settings

Refine official PVWatts v8 inputs. The quick-estimate defaults are suitable for a first result.

DC-to-AC size ratio Panel DC capacity divided by inverter AC capacity. Higher values can increase inverter clipping.

Inverter efficiency (%)

Ground coverage ratio The fraction of ground occupied by array rows; it affects row spacing and self-shading.

Albedo The share of sunlight reflected by the ground; weather-file values are recommended for a first estimate.

Bifacial

Bifaciality factor Rear-side/front-side efficiency ratio; typically 0.65–0.9.

Monthly irradiance loss (%) PVWatts API “soiling” loss, January through December.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

API access Optional

Personal NLR API key

Most quick estimates work without a personal key. For 77-run comparisons, a free key helps avoid shared DEMO_KEY limits. It is sent only with PVWatts requests and is not stored or exported. Get a free key.

Calculating with official PVWatts v8 and current NSRDB data…

Annual AC Energy

—kWh

Usable electricity delivered by the modeled system over one year.

Solar Radiation

—kWh/m²/d

Average daily sunlight received by the array plane across the year.

Capacity Factor

—%

Actual annual AC output divided by continuous full-power output.

Energy Yield

—kWh/kW

Annual AC energy produced per kilowatt of installed DC capacity.

Monthly AC energy output

Monthly solar radiation

Monthly performance breakdown

Renton, WA · Official PVWatts v8 / NSRDB

Monthly solar radiation, plane-of-array irradiance, DC energy, and AC energy. This table is the accessible alternative to the monthly charts.
Month	Solar radiation (kWh/m²/day)	Plane of array (kWh/m²)	DC energy (kWh)	AC energy (kWh)

Tilt & azimuth comparison

Compare annual AC energy across 77 orientations while holding your current system assumptions constant.

77 API requests

Comparison baseline

Location: Renton, WA
System size: 4 kW DC
System losses: 14.08%
Module / array: Standard · Fixed (open rack)

Advanced model settings are inherited from the current simulator inputs. Only tilt and azimuth vary.

Quota checkpoint

A personal NLR key is recommended. The sweep runs in 7-request batches so cancellation prevents unsent batches from consuming quota.

I understand this comparison can use up to 77 PVWatts API requests.

Acknowledge the request count to enable the sweep.

Run the comparison to reveal the best-performing orientations for this system.

View accessible comparison data