Development of a thermal and photovoltaic solar panel

Supporting the R&D of a coating for a thermal and photovoltaic solar panel

TRL9 Ltd is a technical research and development (R&D) company developing a solar fluidics device. This is a solar panel with a combined heat and power unit to provide hot water and electricity to small dwellings in off-grid locations or densely populated and impoverished communities.

TRL9 has worked with CPI on reviewing relevant technologies currently available and developing their solar panel. The aim was to improve the solar panel’s absorption of thermal energy and to integrate a photovoltaic (PV) layer to harvest electricity from incident light.

This work was carried out as part of CPI’s Project IMPACT (Innovative Materials via Precision Additive Coating Technologies), which was part-funded by the European Regional Development Fund (ERDF).

“ The highly supportive and skilled teams at CPI have helped us access the funding, research methods and expertise we needed to bring our solar panels to market. ”
Bryan Allcock, Group CEOTRL9 Limited 



An input is a unique capability, service or method of support that was provided, such as equipment or expertise.

  • ERDF funding via the IMPACT Project 
  • Additive manufacture and design expertise 
  • Printable electronics expertise 
  • State-of-the-art facilities 


An output is the result of the work, such as an experimental finding, an actual product or a pilot demonstrator.

  • Technical review and desk research of thermally absorbent black coatings and printable photovoltaic technologies 


An outcome arises from implementing the outputs, for example, a profit, an investment, providing jobs or delivering societal benefits. Outcomes continue once an innovation has been implemented and deliver benefit every year.

  • Understanding of the available options for black coating materials for most effective and efficient thermal transfer, with specific prototyping options identified 
  • Understanding of the available options for third-generation PV coatings for the solar panel 

The challenge

A low-cost solar heat and power panel is needed to support small, off-grid and high-density dwellings, particularly in the developing world. 

TRL9’s solar fluidics project is a solar thermal and third-generation photovoltaic combined heat and power unit. The triangular, tessellated unit is characterised by its low cost per watt per unit area. However, innovations are still needed to support its development.

TRL9 needed to develop a suitable black-body, spectrally selective coating for its solar thermal and photovoltaic panel to warm the water flowing through the heat exchanger using captured solar thermal rays. This black-body coating is needed to improve the absorption capacity and efficiency of its solar panel. This challenge required expertise in third-generation PV coatings, materials and research methods. 

To help achieve these goals, TRL9 approached CPI to access funding, expertise and facilities for research and development work.

How CPI helped

Working with CPI, TRL9 secured funding through Project IMPACT, which is delivered on behalf of the ERDF. The aim of this project was to gain a better understanding and conduct a technical review of black-body thermal absorption and photovoltaic technologies for TRL9’s thermal and photovoltaic solar panel.

CPI helped TRL9 with a literature review of potential materials that could be used to formulate a black coating with high thermal conductivity and emissivity for the solar panel. This included examining commercial coating materials available on the market, exploring ingredients for a novel formulation and considering viable methods to create a new coating system.

CPI additionally helped with a literature review of third-generation PV materials and device stacks to establish whether it could be applied to TRL9’s solar panel. As a result of the collaboration with CPI, the product has progressed to prototype development for a launch in 2021.




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