Specific yield
Annual energy produced per unit of installed PV capacity, expressed in kWh/kWp per year; combines solar resource and system performance.
Specific yield, also called final yield, divides a PV system annual AC output by its DC nameplate capacity. It is the single most useful number for comparing sites and estimating revenue, because multiplying it by system size gives annual energy.
Typical specific yields for fixed, optimally tilted systems (PVGIS, Global Solar Atlas):
- UK, Denmark, northern Germany: 850–1,000 kWh/kWp
- Southern Germany, northern France: 1,000–1,150
- Spain, Italy, Greece: 1,350–1,650
- Southwest US, Middle East, Australia: 1,700–2,000
- Atacama with single-axis trackers: 2,400–2,800
Single-axis tracking typically adds 15–25% in sunny regions, and bifacial modules another 5–10%. Dividing by 8,760 hours converts specific yield into a DC-based capacity factor: 1,000 kWh/kWp equals 11.4%, 2,000 kWh/kWp equals 22.8%. Note that capacity factors quoted on an AC basis are higher when the DC/AC ratio exceeds 1.
Specific yield also drives the solar LCOE: doubling the yield roughly halves the cost per kWh for the same capital cost.
Related terms
All terms →- Performance ratio
Ratio of actual AC energy output to the theoretical output implied by plane-of-array irradiation and nameplate capacity; a location-independent quality metric for PV plants.
- Capacity factor
The ratio of the energy a power plant actually produces over a period to the energy it would produce running at full nameplate capacity for the whole period.
- Irradiation (insolation)
Solar energy received per unit area over a period, usually expressed in kWh/m² per day or per year; the time integral of irradiance.
- Full-load hours
The number of hours per year a plant would need to run at rated power to deliver its actual annual output; equal to capacity factor multiplied by 8,760.
- LCOE (Levelized Cost of Electricity)
The constant price per MWh that recovers all lifetime costs of a power plant, discounted to present value, divided by its discounted lifetime output.
- DC/AC ratio
Ratio of a PV array DC nameplate capacity at STC to its inverter AC rating; also called inverter loading ratio (ILR).