Solar thermal

A solar thermal system could meet most of your dairy farm hot water requirements during spring and summer, and potentially result in a 50% cost saving across the year.

The daytime requirement for hot water has an obvious correlation with the availability of solar energy, and thermal systems can often heat water without assistance from electricity. Some examples exist of solar thermal arrays providing for all of the hot water needs in the summer season. However, around the year it is reasonable to expect a 50% saving.

Flat Plate Collectors feature a matt black absorber behind a glass sheet; absorbed heat is then transferred to a circulating liquid. More expensive Evacuated Tube Collectors avoid the loss of collected heat via conduction. Either type requires an unshaded pitched roof or mounting frame site, facing approximately south and as close as possible to the thermal store location.

As with heat pumps, solar thermal requires the installation of a preheat buffer to collect the solar energy before passing the preheated water to the existing electric unit. This will raise it to full temperature when necessary. There are many good examples where solar thermal systems can produce a dairy farm’s hot water requirement in mid-summer without the need for further heating. Advances in collector technology are expected to extend this potential so that six months plus without water boost is realistic (when solar conditions allow).

The Renewable Heat Incentive (RHI) scheme makes solar thermal even more attractive but closes to new applicants after March 2022.