Our energy supply is becoming cleaner and less centralised. This is due in large part to a fall in the investment cost sof renewable self - generation technologies , such as solar photovoltaic (PV) installations. Detached home - owners have been the first to take up, and benefit from, solar electricity self - generation , in particular where public incentive schemes have been set up . But other parts of society have so far been unable to access this source of energy, including tenants in multi - storey buildings. As many as around 150 million E