Most of us are now aware of solar panels that heat water and those that produce electricity. But could we install a panel to do both?

Solar PVT (PV and thermal) is a concept designed to create electricity and use the waste heat (solar PV panels are only about 15% efficient and the rest of the energy has to go somewhere) for heating.

Sound perfect? Well there are some conflicting reports on this subject. Some say PV cells are more efficient at lower temperatures and thermal panels take the heat away from the panel to use elsewhere. So a combined panel should produce more electricity and about the same amount of heated water for the same area of panel.

Others say that solar PV should be operated at less than 30C, solar water heaters at around 50 to 60C and therefore the 2 are simply not compatible.

There is also the "ouch" factor of putting water and electricity quite close together.

There do appear to be products available in the market although they may be expensive and difficult to be sure of their efficiency. It does appear to be the case that the heat produced is "low grade" heat and better suited to underfloor heating (maybe in conjunction with a heat pump) or for heating swimming pools where lower temperatures are required. 

There is also a system becominng available in the USA which uses the heat to heat the air which is drawn under the panels and directed through intake vents to be used for heating or hot water generation through heat exchangers.

It is early days for this technology and probably safer to install the technology that we know works. However we will be keeping an eye on this technology as a company! 

Photo by Nasa Godard Photo and Video

About the author: Paul Hutchens is founder and director of Eco2Solar, which installs solar systems around the UK.

If you have a question about anything in the above blog, please ask it in the comments section below.