Zero carbon solar controller
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Zero carbon solar controllers use solar electricity generated on-site rather than mains electricity to pump solar hot water. Zero carbon solar controllers are currently being developed in the United Kingdom and other European countries.
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[edit] Purpose & Design
The zero carbon solar controller uses solar electricity produced on-site in a photovoltaic (PV) panel to run the pump which delivers the solar-generated hot water to the hot water store. A zero carbon solar controller contains an electricity store in addition to the same components as a normal solar controller. This electricity store is usually in the form of supercapacitors, since these have a much longer life than batteries. The electricity store allows the controller to remain powered and display temperatures at night when there is no sunlight.
[edit] Benefits
The benefits of a zero carbon solar controller are that the 20% carbon clawback associated with conventional solar thermal panels is avoided, provided that the pump used is also powered by photovoltaics.[1] This sustainability benefit comes with a slight panel performance reduction of in the range of 1-10%. This relates to the times when the panel may be slightly hotter than the water store but when there is not enough power from the PV to turn the pump on. This happens mainly on hot days in summer, at times when hot water is likely to be in excess, so this potential reduction may not be as significant as it may first appear. Currently (2007) a minority sub-technology within an already minority technology; it is however possible that the global solar thermal industry will start to adopt zero carbon controllers more widely in the future. This may happen if the terms of reference of solar thermal start to turn away from maximising component efficiency, which is usually regarded as efficiency per square metre of panel, and moves towards system sustainability. System sustainability may be assessed in a variety of terms, for example, operational carbon input/output ratio. This ratio is zero for a range of zero carbon solar technologies such as PV pumped solar, thermosiphon solar and integrated collector and store solar systems.
[edit] References
- ^ Martin C, Watson M (2001). "Side-by-side Testing of Eight Solar Water Heating Systems" (PDF). . United Kingdom Department of Trade and Industry Retrieved on 2007-08-04.
[edit] Further Reading
- Solar Twin Ltd (2007). "Request for EN 12975 solar thermal panel standard to be re-examined on the grounds that its durability test is no longer inclusive enough to facilitate a thriving innovative solar thermal market in Europe and the world." (PDF). Solar Twin Ltd. Retrieved on 2007-08-04.
- Martin C, Watson M (2002). "Further Testing of Solar Water Heating Systems" (PDF). United Kingdom Department of Trade and Industry. Retrieved on 2007-08-04.
