Existing solar collectors have been categorised, reviewed and analysed. Areas where there is a paucity of information have been identified including the fixing and framing systems of solar thermal facades as well as cheaper lower efficiency solar thermal façade solutions.

A greater range of building integrated solar thermal collectors is required in order for the solar thermal market to expand further. For each application, location and facade typology a specific solution is best suited.

Colour inclusion has been identified as one common requirement for building integration by many authors. Using state of the art coating technologies to achieve blue and yellow collectors resulted in efficiency decreases between 3 and 11% when compared to un-coloured collectors.

Integrating the collector directly to the walls insulation reduces the heat loss through the back of the collector resulting in efficiency increases for any time and location where the temperature of the collector is greater than the ambient temperature.

Overheating risks are primarily associated with flat plate collector based STFs integrated into the building’s insulation.

Solar thermal façade products based on flat plate collectors or evacuated tube collectors exhibit the highest efficiencies.

While, novel and bespoke products often have lower efficiencies they fulfil other functions such as shading and building insulation, which can enhance building efficiency.

Novel solar thermal façade solutions include solar collectors integrated into balcony rails, shading devices, louvers, windows or gutters.