Direct and indirect benefits of grid connected photovoltaics in low energy social housing

The direct benefits of a photovoltaic system to a homeowner or tenant are easy to predict in terms of a reduction in electricity bills. There is an additional indirect benefit of the PV system in that it can change people’s attitude towards energy usage and conservation. This paper reports on a study of the direct and indirect benefits of PV applied to nine low energy Eco-homes in Hampshire, UK. The three bedroom houses incorporate a range of energy features including photovoltaics, solar thermal, passive solar design, high insulation construction, energy efficient appliances and grey water recycling. In addition to detailed monitoring of the PV system in each house the environmental parameters and the electricity import and export is also recorded. The diverse range of tenant type (age, social background, family size) has resulted in a broad spectrum of energy requirements despite the relatively small size of the development. The selection of green electricity tariffs by some tenants; which credit the tenant for every unit of electricity generated; were seen to raise energy awareness, resulting in a further reduction in electricity demand. In the case of some of the high energy consumption tenants, the PV system raised energy awareness to such a level that energy savings in excess of that generated by the PV system itself could be realised. In these cases, the financial and energy payback times for the PV systems are, in reality, half the traditionally calculated figure.