What Is Specific Yield in Solar? Definition + Benchmarks
Last updated: 2026-04-08 · Solar Benchmark
What Is Specific Yield in Solar? Definition + Benchmarks
Specific yield is annual energy production (kWh) divided by system size (kW). A 6 kW system producing 9,000 kWh per year has a specific yield of 1,500 kWh/kW/year. For US residential systems, typical specific yield ranges from 950 kWh/kW/year in the Pacific Northwest to 1,950 kWh/kW/year in the Desert Southwest.
Definition and How It Works
When comparing solar systems, raw production numbers are misleading. A 12 kW system that produces 18,000 kWh per year is not outperforming a 6 kW system that produces 9,600 kWh per year. Specific yield removes system size from the equation so you can make an honest comparison.
The formula is simple: divide total annual kWh by system nameplate capacity in kW. The result tells you how hard each kilowatt of installed capacity is working. A higher specific yield means the system is converting available sunlight more efficiently, facing fewer losses from shading, soiling, or suboptimal tilt.
Specific yield is the correct metric when you want to benchmark one system against regional averages, track year-over-year performance for the same system, or evaluate whether an installer's production estimate is realistic for your location. See how our physics engine calculates expected specific yield for each address.
Specific Yield Benchmarks for US Residential Systems
| Region | Specific Yield (kWh/kW/yr) | Representative Cities |
|---|---|---|
| Desert Southwest | 1,800 - 1,950 | Las Vegas, Phoenix |
| California Inland | 1,650 - 1,870 | Riverside, Sacramento |
| California Coast | 1,440 - 1,580 | Los Angeles, San Francisco |
| Southeast | 1,400 - 1,520 | Atlanta, Tampa |
| Mid-Atlantic | 1,300 - 1,420 | Washington DC, Baltimore |
| Midwest | 1,180 - 1,290 | Chicago, Columbus |
| Pacific NW (east of Cascades) | 1,420 - 1,560 | Spokane, Yakima |
| Pacific NW (west of Cascades) | 950 - 1,080 | Seattle |
These ranges reflect well-installed residential systems with no significant shading and standard south-facing orientation. Systems with east or west-facing panels, partial shading, or poor tilt angles will fall below the regional lower bound.
What Affects Specific Yield
- Irradiance and geography: The amount of solar radiation reaching your roof is the primary driver. Desert and southern locations receive substantially more annual irradiance than northern or coastal locations.
- Tilt angle and orientation: South-facing panels at a tilt close to local latitude maximize annual yield. East or west-facing panels reduce specific yield by 15-25% compared to true south.
- Shading losses: Even partial shading from trees, chimneys, or neighboring structures during peak sun hours can reduce specific yield significantly, especially in string inverter systems.
- Soiling: Dust, pollen, and bird droppings on the panel surface reduce the irradiance reaching the cells. In dry climates with infrequent rain, soiling losses can reach 3-5% annually.
- Temperature: Panels lose efficiency as they heat up. Hot climates with high irradiance partially offset their advantage through temperature-related losses.
Frequently Asked Questions
What is a good specific yield for my location? Compare your system's specific yield to the regional range in the table above. If your system falls below the lower bound for your region, it warrants investigation. Common causes include shading that wasn't accounted for in the original design, inverter clipping, or a system that is underperforming due to equipment issues.
Why is specific yield better than just looking at total kWh? Total kWh production is a function of both system size and performance. Specific yield isolates performance. Two neighbors can have very different system sizes, but comparing their specific yields tells you whose system is working better relative to what was installed.
Is specific yield the same as performance ratio? No. Specific yield measures absolute production per kW installed. Performance ratio (PR) compares actual production to the theoretical maximum for your irradiance conditions. Both metrics are useful: specific yield tells you what you got, PR tells you how efficiently you converted what was available.
Data: pvlib physics modeling + Open-Meteo ERA5 weather data | Last updated: 2026-04-08 | Solar Benchmark