The embodied energy payback period of photovoltaic installations applied to buildings in the U.K.

Developments in the design and manufacture of photovoltaic cells have, over the last few years, been very rapid such that they are now predicted to become a major renewable energy source for buildings. This paper considers the embodied energy in photovoltaic modules applied to U.K. buildings, and determines a payback period in terms of the embodied energy rather than cost. The embodied energy payback is important for renewable technologies as their use makes no sense if the energy used in their manufacture is more than they can save in their life-time. The embodied energy payback period should always be one of the criteria used for comparing the viability of one renewable technology against another. The results show that, for the U.K. buildings studied and for an optimistic scenario with an ideal location with no overshadowing and without the use of storage batteries, the embodied energy payback period for photovoltaic modules is in the region of 8–12 years. At present therefore other renewable technologies would appear to be more suitable for the U.K. Photovoltaics applied to buildings may be a realistic option in climates with higher levels of solar radiation. They may also prove to be successful in the future in the U.K. if photoelectric generation efficiencies improve substantially, or economies are made in the manufacturing process.