Understanding your specific yield
What specific yield actually measures
Specific yield is a system's annual energy output divided by its size in kW, expressed as kWh per kW installed. An 8 kW system producing 10,500 kWh a year has a specific yield of about 1,312 kWh per kW, a figure that lets you compare systems of any size on equal footing. A DOE study of federal PV systems found system size ranged from 1 kW to over 4,000 kW in its sample, with specific yield varying accordingly by design and location.
Typical specific yield ranges by US region
The Southwest typically sees 1,500 to 1,900 kWh per kW, the Southeast 1,300 to 1,600, the Northeast and Midwest 1,100 to 1,400, and the Pacific Northwest 1,000 to 1,250. These ranges reflect regional differences in sunlight, not system quality, so a system performing at the top of the Pacific Northwest range isn't underperforming compared to a Southwest system in the middle of its range. National Solar Radiation Database show this same regional pattern visually, making it easy to see roughly where your own location should fall within the national range.
Why this beats comparing raw kWh totals
Raw annual kWh output depends heavily on system size, so a bigger system will always produce more total energy even if it's less efficient per panel. Specific yield removes that size difference, making it possible to fairly compare a 5 kW residential system against a 500 kW commercial one. This is why specific yield shows up constantly in solar industry reports and installer proposals.
What a low specific yield relative to your region suggests
A specific yield below your region's typical range can point to shading, soiling, an underperforming inverter, or a less-than-ideal tilt or orientation. It's worth investigating with a licensed installer if your figure sits noticeably below the regional benchmark, since that gap usually traces back to a fixable issue rather than bad luck. The annual inspection cost estimator can help weigh whether a professional diagnostic visit is worth the cost for your situation.
What to do with this number next
Compare it against the capacity factor calculator and performance ratio calculator for two related but distinct ways of framing the same underlying performance.