The British Library – a high-profile reference for PVT systems
Naked Energy reached two important milestones for its PVT technology in 2024. The British company received a Solar Keymark certificate for the VirtuPVT collectors in October 2024. A few days earlier, a press release was published about a high-profile reference using this type of hybrid collector on the roof of the British Library in London (see photo). A total of 240 VirtuPVT and 710 VirtuHOT collectors totalling 712.5 m2 supply space heating and sanitary hot water, and contribute to the heat-driven dehumidification system of the historic institution’s rare books section. Over the past two years, new certificates for several PVT suppliers have been added to the Solar Keymark database – these are Consolar and Sunmaxx PVT from Germany, Triple Solar from the Netherlands, Dualsun from France and Abora Solar from Spain. Naked Energy is the first company to be awarded a certificate for an evacuated-tube-based PVT collector. All the certificates can be downloaded here.
Photo: Naked Energy
“It’s an honour to partner with such an iconic British institution as the British Library and be a part of their journey to meet their net-zero goals,” said Christophe Williams, Founder and CEO of Naked Energy. First and foremost, the solar heat is used to supply sanitary hot water and space heat in the building, and also contributes to the heat driven dehumidification system of the rare books section, so that the books and texts, some of which are several centuries old, are always kept under ideal conditions.
Naked Energy has an online monitoring system with which the performance of the system on the roof of the library can be monitored constantly. The team is satisfied with the results of the first year of operation, which were presented by Naked Energy at Eurosun in August 2024. The solar thermal yield of the 180 m2 PVT field was 297 kWh/m2, which was more than simulated, whereas on the electricity side the yield of 72 kWh/m2 was slightly lower than expected (-2.5 %).
Figure 1: Design of VirtuPVT collectors. The mirrors between the tubes guide the light beams directly onto the absorber and increase the efficiency. Graphic: Naked Energy
Flexible installation by adjusting the incidence angle of the absorber
The elements consist of 19 cm-wide evacuated single-glass tubes, which include an aluminium absorber laminated with PV cells. According to Williams, the company is conscious of the carbon footprint of its products. Naked Energy purchases the glass tubes from Germany to profit from short transport routes. Only the glass caps are shipped from China. The assembling is done in the UK. A U-formed copper pipe carries the heat transfer fluid from the absorber to the manifold. The critical point is the metal-plastic-glass seal where the two metal pipes leave the glass tube to be connected to the manifold (see figure 2).
VirtuPVT collectors can produce up to 75 °C. They can be installed on façades as well as inclined and flat roofs as the incidence angle of the absorber within the tube can be adjusted according to the site and the installation.
Naked Energy also offers a vacuum tube collector without PV under the product name VirtuHOT which can reach up to 120 °C. The company was founded in 2012. Virtu collectors have been commercially available since 2018. According to Naked Energy, the Virtu product range has been sold to more than 20 countries and is well-established in the UK and Europe.
Figure 2: The critical part of the production is the seal between the glass cap and the metal tubes which carry the heat transfer fluid from the absorber to the manifold. Photo taken from the film about the British Library. See here: https://nakedenergy.com/case-studies/british-library
Heat-as-a-service offered in cooperation with E.ON Energy Infrastructure Solutions
Naked Energy secured a large amount of funding for the acceleration of the international rollout of Virtu collectors in summer 2024. In the first close of its Series B capital raise, the company received GBP 17 million from E.ON Energy Infrastructure Solutions (EIS) and Barclays, who are both shareholders of Naked Energy. “It’s clear that both E.ON and Barclays share our sense of urgency to decarbonize heat”, commented Williams when the deal was announced. According to the press release from July 2024 it took only one year from scouting to signing the strategic partnership between E.ON and Naked Energy.
“EIS is an accomplished partner providing integrated, sustainable, and digitally-enabled energy solutions for cities and industries to reduce their carbon emissions. Operating in over 16 European countries, EIS services 1.5 million customers through 4,500 plants”. This is how Naked Energy described the partnership in its press release last summer.
The major outcome from the new shareholder structure is that Naked Energy and E.ON EIS now offer heat-as-a-service contracts to finance large-scale industry and city decarbonization projects.
In such a heat purchase agreement everything is packaged into a reliable contract that meets the business’s needs and sets a heat price which is lower than the price of heat produced by fossil fuels. Importantly, the upfront costs are funded by E.ON EIS, so the installation costs don’t affect the client’s balance sheet, freeing up resources for other parts of their operation.
Websites of organizations mentioned in this news article:
Naked Energy: https://nakedenergy.com/
Consolar Solar Energiesysteme: https://www.consolar.de/en/home_en/
Sunmaxx PVT from Germany: https://sunmaxx-pvt.com/
Triple Solar: https://triplesolar.eu/
Dualsun: https://dualsun.com/en/
Abora Solar: https://abora-solar.com/en/ed?
