SolarUK's Glossary of Solar Energy Terms
Many terms used to describe solar energy can be new and confusing. We have provided a list of the most used terms below. Click on the word for an expansion of the term.
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The collection of the sun's energy as heat rather than converting it to electricity.
Vacuum Tube Solar Collector
This is a technology that uses a glass tube, think of a long thermos flask to insulate the solar collector and ensure that effectively all solar energy is retained.
Feed in Tariff
A method to reward the producer of renewable energy (electricity) by paying a fixed amount of money for each unit of electricity generated.
Renewable Heat Incentive (RHI)
A feed in tariff for renewable generation of heat as an alternative to the use of fossil fuels.
Recirculation - pumped secondary
Pipework carrying secondary hot water.
Sequential heating arrangement
The heating that occurs as the solar thermal system heats the water before the conventional heat source provides any necessary additional heating.
Stores the suns energy as heat captured by the collector.
Refers to any period when the heat transfer fluid is not circulating, even though the solar panel is receiving the suns energy.
Primary and secondary systems
This refers to the water travelling round the boiler and the water in the cylinder which is heated by it.
Stratification / de-stratification
The layering of hot water on colder water.
A trapped volume of pressurised air or gas inside a steel vessel to allow for the expansion that accompanies temperature increases.
A tank storing heated water in anticipation of variable demand requirements.
A cylinder placed between the cold water feed and the existing hot water cylinder.
Any pipe with several outlets to or from other pipes, or a junction of pipes.
A water storage vessel, which has the capability to increase the temperature of the water contained within it.
The controller compares the different temperatures at specific locations in the solar systems circuit.
The heat exchanger is normally inside the hot water cylinder. It transfers heat in the solar circuit (which has been water warmed by the sun) to the water inside the hot water cylinder/ tank.
Circulation module / Pump module
Operates the heat transfer system.
Collector (Solar Thermal)
A device, also called a ‘panel’, which collects the sun’s energy and converts it into a more usable form.