The Energy Saving Trust estimate that fitting PV solar panels will save the average household £120 a year in electricity bills. This is based on 50% of the power generated being used by the householder. As there is no way of storing the power generated by the solar panels, the energy will be generated during the day when most homes are unoccupied. In reality, this means that savings would be around £70 or less a year.
For anyone that can afford to pay for their own panels to be fitted, this will not matter as they will be selling all the unused energy generated from their solar panels to the national grid. This will earn around £1000 per year from the feed-in tariff scheme, guaranteed to last 25 years, with payments rising with inflation.
Those who sign up to one of the 2,000 'rent a roof' schemes that install the panels for free (normal cost is around £14,000) they may save the installation cost, but gain no benefit at all from selling surplus energy to the grid. So in return for an average saving of just £5 per month in electricity costs, those that 'rent a roof' will have equipment owned by someone else on their roof, which could reduce the resale value of their home and a complicated the sale.