It’s time to look again at solar thermal.

The strategic importance of this mature, proven technology is growing as our homes become more thermally efficient and require less space heating – we will continue to need hot water. The UK also needs to do much more to decarbonise heat, where we lag badly behind in Europe.

Solar thermal is well suited to smaller, urban homes, where space is at a premium and where good air quality matters. This makes it perfectly suited to crowded UK cityscapes. And it is particularly good for tackling fuel poverty given negligible running costs and reliable cost savings. Solar thermal is certainly solid technology; 91% of surveyed applications to the Renewable Heat Incentive (RHI) were satisfied with the reliability of their solar thermal system.

So now is the time to shake off UK preconceptions about solar thermal and to look again.  Solar thermal can do a lot more in our efforts to decarbonise and improve air quality than a hot shower.

Our new report Solar Thermal Now showcases the very wide range of applications of solar thermal today, including on health centres, farms, swimming pools, industrial processes and even as the heavy lifter in district heating. One of the largest solar thermal schemes in the world, in Silkeborg, Denmark, provides a fifth of the heat for the district heating for a town of 43,000. And yes, it does still do great hot showers – a new installation on the prestigious 100 Minories Hotel under construction by Tower Bridge will meet half the hot water needs of 268 bedrooms.

In the UK, support for solar thermal under the RHI is available for schemes up to 200kW in size and returns are decent. That gives lots of scope for action. Unfortunately, the RHI does not support other key applications of solar thermal such as space heating, now common in Europe, and innovative technologies like PV-T (in which solar thermal and PV combine).

Nevertheless, solar thermal has tremendous possibilities including for engineering together with other technologies in order to provide highly efficient and very low-carbon heating systems. Solar thermal works beautifully with other technologies. It can do the heavy-lifting during the warmer months, saving the boiler on inefficient start-ups for short bursts of hot water. And it can keep heat pumps focussed on lower temperature space heating, where they work so efficiently.

The EU LabelPack+ labelling scheme, which has been compulsory for products and packages up to 70kW in size since 2015, shows that you need to incorporate renewables in your system to achieve the top A+++ performance rating today. The label also allows you to understand how your solar thermal system will work alongside other technologies, such as boilers, heat pumps or PV. A ‘package fiche’ will show you how your system will perform overall.

It’s a common myth that solar thermal can’t work with combi boilers. That’s one myth we’ll be looking to bust when we take our new report to the big Chelsea Phex show tomorrow. The UK industry has engineered clever solutions that allow easy integration with combi-boilers. Major boiler manufacturers such as Worcester Bosch and Veissmann offer combi boilers that can accept preheated water from solar thermal systems. And yes, solar thermal can work even when its cold – as demonstrated across the Nordic countries, where it is prolific. 

Analysis by IRENA shows solar thermal could technically meet half of heat demand in the industrial sector. Indeed half of industrial heat requirements are for medium to low temperatures, such as washing, drying, sterilising & pasteurising. This makes solar thermal, which can do very hot process steam, well suited to sectors where heating needs are below 250c, such as paper, chemicals, tourism, pharmaceuticals & textiles. The farming industry also offers great opportunities. 

So we invite you to look again at solar thermal. We hope our new report will also help others to explain the tremendous value of this important technology. The economics can work. The carbon savings are solid. All we need to do now is get the word out.