Case Study



Heriot-Watt University




Glasgow & Clyde Valley


Stuart Speake founded Soltropy Ltd in 2012 to bring to market an innovative solar thermal panel system.

Solar thermal heating systems reduce CO2 emissions by displacing the use of fossil fuels. According to the Energy Saving Trust (EST), a solar thermal panel saves between 230kg and 510 kg per year depending on which fuel it is displacing.

Most solar thermal systems have a separate antifreeze filled loop for protection against freezing and require a new tank fitted with a heat exchanger. When retrofitting, a perfectly good tank (usually copper) needs to be replaced. The Glasgow‐based company, Soltropy Ltd, has developed an innovative solution that allows the fluid in the panels to freeze without causing system damage, allowing the system to be set up to heat water directly, negating the need for a new hot water tank and potentially reducing the system cost by 50%. 


The company was looking for academic expertise to provide solid data on the overall system performance.


After hearing about Interface at an event, Louise Arnold was able to put the company in touch with Dr Tadhg O’Donovan from the Energy Academy at Heriot Watt University.  Thanks to the University’s support, Soltropy was awarded a £5,000 Scottish Funding Council Innovation Voucher, administered by Interface, which helped to offset the cost of the project.

The project is now finished with the software model developed. This has proved to be very useful to the company, indicating clear areas where the design can be modified, resulting in different characteristics.

Follow On

This collaboration lead to a grant of £6.5 K from the ETP consultancy fund being secured to build a prototype and carry out comparison testing with an incumbent solar thermal system.  Testing was carried out at the Heriot-Watt University Renewable Energy Test site with the installation of two evacuated tube solar panels.  One panel was modified to incorporate the Soltropy technology; with instrumentation installed to measure fluid flow rates and fluid temperatures so as to determine an accurate thermal performance for the duration of the project. The work was carried out by two Mechanical Engineering students, funded by student bursaries, as part of an MSc programme in the School of Engineering and Physical Sciences. 

In December 2014, Soltropy, along with project partners Heriot-Watt, succeeded in securing Innovate UK (formally Technology Strategy Board) funding with a grant of almost £175k as part of the Early Stage Energy Catalyst.

Tests at Heriot‐Watt University have shown that the Soltropy system behaves differently from the “old style” systems and requires a different control strategy.  The main aims of the year long project is to investigate what type of strategy would be appropriate along with some new innovations to further reduce the cost of the system. The project partners have received a grant of £90k which will fund a Research Associate full time, and ultimately extend their collaborative project.


Soltropy Ltd has benefited from the collaboration with a more optimised system through theoretical modelling.  It now has data to back up claims it will make when convincing potential investors and, ultimately, installers and consumers, of the superiority of the system.

The initial project brought the University increased understanding of solar thermal systems and gave them the opportunity to work with Soltropy under a larger funded programme to further develop the project.

As this system will be manufactured in Scotland and sold worldwide, the Scottish economy will benefit from an increase in employment and revenue.

“Interface has helped immensely with my journey from my initial idea to a validated tested product. They were the initial help in partnering us up with academia to help in taking it from this idea, through software modelling and then actual lab and onsite testing.”  Stuart Speake, Soltropy

“I can honestly say that without Interface I doubt that my innovation would have gotten off the ground” said Stuart after winning the Sustained Partnership award at the 2016 Scottish Knowledge Exchange Awards.


In June 2016, Soltropy were awarded the £100k Scottish Edge Higgs award.

Higgs EDGE is a special award aimed at entrepreneurs who have a company that has applied leading edge technology to an innovative product, or product under development in the Science, Technology or Engineering sector, which is potentially world leading and also has the potential for large scale global commercialisation.

Soltropy also received an Energy Technology Partnership fund of £6.5k to build a prototype and carry out comparison testing with an incumbent solar thermal system.

Two further projects involving Soltropy have recently been funded by the Innovate UK Energy Catalyst scheme:

1.       Reducing the Cost of Solar Thermal: Integrating a Novel Freeze Tolerance Approach with Flat Plate Solar Thermal Panels

2.       Reducing the Cost of Solar Thermal: Integration of Thermal Storage with Solar Collector Design

The combined funding for each of these projects totalled £200k.

Please note that Interface administers the Innovation Voucher Scheme on behalf of the Scottish Funding Council. All funding applications are reviewed on a case by case basis by the Scottish Funding Council, guidelines can be found here.