Southwest Environmental Limited

Which Solar Panels are the most Sustainable?

To the casual eye the two solar panels look very similar but the technology in side is very different. The one to the left produces electricity, the one to the right produces hot water. But which is best?

Solar PV

Solar PV panels take sunlight and turn it in to Electricity. They are by far and a way the most popular type of solar panel in the UK. Especially where you might see then in large arrays dotting the countryside.

Image: SayCheeeeeese [CC0], via Wikimedia Commons 

Solar Thermal

The answer is that Hot Water is best but only up to the amount you can make use of. If you want extra then  . . . . Electric Photovoltaic Panels. Why?

Image: SolarCoordinates [CC BY-SA 3.0], via Wikimedia Commons

Example - Health Care Development

A hospital in the planning phase needs to outline emissions reductions to the tune of 20%.

17.5% of the building energy demand will come from heating water, for washing and bathing etc. So we can use solar thermal panels for this, generating 700 KWh / pa / m2 we install 48 m2 to provide 17.5% of the buildings energy at a zero carbon rating.

35 m2 photovoltaic panels  meets the remaining 2.5%, as they only produce 140  KWh / pa / m2.

So as a rule maximise hot water panels, and then top up with PV panels. Hot water panels can also be used for space heating if combined with a thermal store of some kind, although heating seasons will be short. Find out why solar panels for hot water are perhaps a better option than solar panels that generate electricity.

The above summary is very generalized, and for a true camparison of which option is the most suitable we would suggest a Life Cycle Assessment of the two panels, taking in to account site specific factors. Of course Life Cycle Assessment is likely not feasible for smaller projects but for large projects or smaller projects that will be repeated, it is worth the effort to find the most sustainable solar panel.