Solarsense has been involved in the design of multiple solar systems for a somerset-based charity providing residential homes for people with learning disabilities.

The installation of 4m2 of evacuated Thermomax tubes at the headquarters of the charity, with a cost of around £4200, has been independently estimated as having a projected payback of £1984 per year, giving a system payback in as little under 3 years.

This is by far the fastest payback we have seen for solar thermal, and is a result of large boilers running on oil, with a low efficiency from those times of the year when they are only at 20 or 30% load. The price of heating oil rose by over 3% per month between October 2007 and January 2008, and as it continues to rise, the payback in real terms of solar thermal becomes ever shorter.

Domestic houses can expect a slightly longer payback than for an installation like this, but the calculations for residences are not far behind.