Glossary
The terms behind the roof, the system and the electrical connection.
- BIPV
- Solar that replaces a building material, such as roofing, cladding or glazing, and performs its building function.
- Solar roof
- A roof with integrated solar. Active panels generate power while matching passive panels complete the covering.
- Active panel
- A roof panel containing solar cells.
- Passive panel
- A matching roof panel without solar cells, used where generation is unsuitable.
- Rack-mounted solar
- Solar modules on mounting hardware above a finished roof.
- BAPV
- Building-applied photovoltaics. Solar added to an existing building surface rather than replacing that surface.
- bifacial
- A solar panel that generates electricity from light reaching either face.
- bifaciality
- The ratio of rear-side to front-side power under comparable test conditions. It is not a prediction of energy gain on a roof.
- albedo
- The fraction of incoming light reflected by a surface. Roof color, condition and surrounding surfaces affect it.
- heterojunction (HJT)
- A silicon solar-cell technology combining crystalline silicon with thin silicon layers.
- standing seam
- A metal roof joint formed by raised, interlocking edges between adjacent panels.
- ballast
- Weight used to hold equipment in place without fastening through the roof.
- dead load
- The permanent weight of the building and installed materials or equipment.
- point load
- A force concentrated at a support or small contact area instead of spread evenly over the roof.
- wind uplift
- Upward force caused by wind pressure acting on a roof or rooftop equipment.
- ASCE 7
- A U.S. structural design standard for loads on buildings and other structures, including wind and snow.
- NEC 690
- The National Electrical Code article covering solar photovoltaic electrical systems.
- rapid shutdown
- A safety function that reduces specified photovoltaic circuit voltages when activated, where required by adopted electrical rules.
- interconnection
- The process and equipment for connecting a generating system to the utility grid.
- net metering
- A billing arrangement that credits exported electricity under the utility’s applicable rules. Credit rates and limits vary.
- kWp
- Kilowatt peak. Rated direct-current power under standard test conditions, not annual electricity generation.
- specific yield
- Energy generated per unit of installed rated power, commonly expressed as kWh per kWp over a stated period.
- extensive green roof
- A vegetated roof with relatively shallow growing media and typically low-growing plants.
- intensive green roof
- A vegetated roof with deeper growing media and more substantial planting and maintenance needs.
- sedum
- A group of succulent plants commonly used on extensive green roofs.