Corrugated sheets make cheap solar heater

Two corrugated plastic sheets, riveted together, provide the means to heat water usingsunlight. The idea is the brainchild of William Mollett, proprietor of Phoebus Energy based near Peterborough. “I came up with the idea a few months ago, when the boiler heating my father’s swimming pool blew up,” he says. The company normally sells solar heating systems based on borosilicate glass vacuum tubes. These use absorbers and heat pipes in the vacuum tubes, in order to minimise convective energy losses within the collectors. The absorb more than 90% of solar energy falling on them but are expensive, Mollett’s idea is to rivet corrugated sheets of black plastic to similar sheets of clear polycarbonate, with passages between them through which the water runs. In a swimming pool, water is pumped to the top of the collectors using the pump that provides circulation and filtration. Ten units, each costing about £120 each, should be sufficient for a reasonably sized pool. This makes the capital cost much less than that of a conventional boiler. The devices could also replace roofing, to heat or pre-heat water for domestic use. A patent has been applied for.