'Hybrid' solar system proves cheaper than photovoltaics

They recently conducted a trial of their system, which uses glass tubes filled with water, methanol and catalyst, based on its exegetic performance — a measure of how much of a given quantity of energy can theoretically be converted to useful work.

‘The hybrid system achieved exegetic efficiencies of 28.5 per cent in the summer and 18.5 per cent in the winter, compared with five to 15 per cent for the conventional systems in the summer and 2.5 to five per cent in the winter,’ said Nico Hotz, assistant professor of mechanical engineering and materials science at Duke.

The team’s hybrid device looks similar to a traditional solar collector but actually contains a series of copper tubes coated with a thin layer of aluminium and aluminium oxide, and partly filled with catalytic nanoparticles. A combination of water and methanol flows through the tubes, which are sealed in a vacuum.

This setup allows up to 95 per cent of the sunlight to be absorbed with very little being lost as heat to the surroundings, facilitating temperatures of higher than 200ºC within the tubes, according to the team.