Solar Energy Wiki topic
Performance
Solar resource, production, and system output.
42 published concepts
Evidence through 2026-06-25 · 12 members have no source-event date
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Starting points
Begin with these concepts
- Solar energy
Solar energy is radiant energy from the sun that can be captured and converted into useful forms of energy.
- Kilowatt
A kilowatt is a unit of power equal to 1,000 watts.
- Annual solar production
Annual solar production is the amount of electrical energy a photovoltaic system generates over a year.
Published directory
All performance concepts
42 total
- Solar energy
Solar energy is radiant energy from the sun that can be captured and converted into useful forms of energy.
GS-CONCEPT-001 - Kilowatt
A kilowatt is a unit of power equal to 1,000 watts.
GS-CONCEPT-007 - Kilowatt-hour
A kilowatt-hour is a unit of energy equal to using one kilowatt of power for one hour.
GS-CONCEPT-008 - Solar system size
Solar system size is the rated power capacity of a photovoltaic system, commonly expressed in kilowatts.
GS-CONCEPT-009 - Annual solar production
Annual solar production is the amount of electrical energy a photovoltaic system generates over a year.
GS-CONCEPT-010 - Solar irradiance
Solar irradiance is solar power incident on a surface per unit area at a particular time.
GS-CONCEPT-032 - Peak sun hours
Peak sun hours express daily solar irradiation as the equivalent number of hours at a reference irradiance of one kilowatt per square meter.
GS-CONCEPT-033 - Photovoltaic shading loss
Photovoltaic shading loss is the reduction in modeled or measured photovoltaic output associated with solar radiation blocked from modules by surrounding objects or terrain.
GS-CONCEPT-034 - Solar array azimuth
Solar array azimuth is the compass direction toward which the array surface faces, expressed under a stated angular convention.
GS-CONCEPT-035 - Solar array tilt
Solar array tilt is the angle between the photovoltaic array surface and the horizontal plane.
GS-CONCEPT-036 - Photovoltaic module efficiency
Photovoltaic module efficiency is the ratio of module electrical power output to incident solar power under stated test conditions.
GS-CONCEPT-037 - Photovoltaic temperature coefficient
A photovoltaic temperature coefficient describes how a specified module electrical characteristic changes with cell temperature relative to stated reference conditions.
GS-CONCEPT-038 - Inverter clipping
Inverter clipping occurs when available direct-current photovoltaic power exceeds the inverter's ability to convert and deliver alternating-current power at that moment.
GS-CONCEPT-039 - Photovoltaic system loss
Photovoltaic system loss is a modeled or measured reduction between an identified reference energy and delivered photovoltaic energy attributable to specified loss mechanisms.
GS-CONCEPT-040 - Photovoltaic performance ratio
Photovoltaic performance ratio compares delivered system energy with a reference yield based on in-plane irradiation and installed capacity over the same period.
GS-CONCEPT-041 - Photovoltaic capacity factor
Photovoltaic capacity factor is electrical energy generated over a period divided by the energy that would result from operating at the stated rated capacity throughout that period.
GS-CONCEPT-042 - Photovoltaic degradation rate
Photovoltaic degradation rate describes the change in a system or module performance metric over time under a stated method and period.
GS-CONCEPT-043 - Photovoltaic production estimate
A photovoltaic production estimate is modeled electrical energy output for a specified photovoltaic system, location, weather dataset, period, and set of assumptions.
GS-CONCEPT-066 - Photovoltaic specific yield
Photovoltaic specific yield is energy generated over a period divided by the photovoltaic system's stated rated capacity, commonly expressed as kilowatt-hours per kilowatt.
GS-CONCEPT-067 - Solar self-consumption
Solar self-consumption is photovoltaic electricity used by loads behind the relevant customer meter instead of being exported to the grid.
GS-CONCEPT-068 - Battery load shifting
Battery load shifting charges storage during one time period and discharges it during another to change the timing of grid imports, exports, or onsite energy use.
GS-CONCEPT-069 - Plane-of-array irradiance
NREL PVWatts reports plane-of-array irradiance as solar irradiance at the array plane.
GS-CONCEPT-121 - Global horizontal irradiance
NREL SAM lists global horizontal irradiance as a weather-data element for photovoltaic modeling.
GS-CONCEPT-122 - Direct normal irradiance
NREL SAM lists direct normal irradiance as a weather-data element for photovoltaic modeling.
GS-CONCEPT-123 - Diffuse horizontal irradiance
NREL SAM lists diffuse horizontal irradiance as a weather-data element for photovoltaic modeling.
GS-CONCEPT-124 - Ground-reflected irradiance
NREL documents albedo as ground reflectance in PVWatts V8 model inputs.
GS-CONCEPT-125 - Bifacial gain
NREL documents bifacial-model inputs for rear-side irradiance and module bifaciality in SAM.
GS-CONCEPT-126 - DC-to-AC ratio
NREL PVWatts defines the DC-to-AC ratio as a positive model input with a default value of 1.2.
GS-CONCEPT-127 - Inverter conversion efficiency
NREL PVWatts documents inverter efficiency at rated power as the inv_eff model input.
GS-CONCEPT-128 - Photovoltaic module mismatch loss
NREL SAM identifies module-voltage mismatch as an electrical loss input on the detailed-PV model Losses page.
GS-CONCEPT-129 - Photovoltaic soiling loss
NREL PVWatts defines soiling as a reduction in incident solar irradiance from dust or other seasonal module-surface soiling.
GS-CONCEPT-130 - Photovoltaic system availability
DOE FEMP defines PV availability as the percentage of time a system is operational and capable of delivering power when the solar resource and grid are working.
GS-CONCEPT-131 - Photovoltaic energy yield
NREL SAM documents Annual Energy and Energy Yield as photovoltaic performance metrics.
GS-CONCEPT-132 - Weather-normalized performance
NREL documents weather-corrected PV performance methods that use calibrated irradiance and measured environmental inputs.
GS-CONCEPT-133 - Performance baseline
NREL Standard Work Specifications calls for system performance benchmark data in photovoltaic owner documentation.
GS-CONCEPT-134 - Nominal operating cell temperature (NOCT)
Nominal operating cell temperature (NOCT) is a PV module’s measured cell temperature under the defined NOCT test conditions of 800 W/m² incident irradiance, 20°C ambient temperature, and 1 m/s wind speed.
GS-CONCEPT-135 - Pyranometer
NREL's weather-corrected performance guidance uses a calibrated pyranometer to measure horizontal irradiance.
GS-CONCEPT-136 - Reference cell sensor
NREL's weather-corrected performance guidance uses calibrated reference cells or modules to determine plane-of-array irradiance.
GS-CONCEPT-137 - Module temperature sensor
NREL's weather-corrected performance guidance uses a shielded thermocouple or equivalent RTD surface-mounted on a module to measure module temperature.
GS-CONCEPT-138 - Inverter telemetry
DOE FEMP says power-conditioning equipment such as inverters often include metering and instrumentation that report parameters to a monitoring system.
GS-CONCEPT-139 - Photovoltaic curtailment loss
DOE FEMP says a PV monitoring platform may receive utility control signals for setpoints such as curtailment of power delivery.
GS-CONCEPT-140 - Low-light photovoltaic performance
NREL reports low-irradiance losses of photovoltaic modules as a module-efficiency behavior considered in PV energy-performance analysis.
GS-CONCEPT-141
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