SolarSub Ltd, a UK solar technology firm developing passive cooling for photovoltaic modules, has closed a £1.34 million investment round to speed up the development and commercialisation of its solution.

The raise was led by Sustainable Ventures, with Zinc VC, Scottish Enterprise, Old College Capital — the University of Edinburgh's venture fund — SFC Capital and the British Business Bank also participating, alongside support from Innovate UK's Investor Partnership programme.

As solar panels heat up, they generate less power and deteriorate faster, cutting output and long-term value.

SolarSub's passive cooling approach is intended to keep modules nearer their optimal operating temperature. With no pumps or moving parts, it aims to increase energy generation, limit heat-driven degradation and enhance the economics of solar projects over time.

The new capital will fund the next stage of technical development and real-world validation, including further product engineering, independent testing and deployments with research, utility and industry partners.

Founded by two University of Edinburgh Engineering graduates, SolarSub plans to run trials across multiple international locations in the coming months as it progresses towards commercial-scale deployment.

Earlier testing has shown strong results in high-temperature conditions. Trials at the University of Edinburgh's FloWave ocean energy research facility recorded an energy uplift of up to 17.5%, while outdoor testing at Heriot-Watt University's Dubai campus delivered peak gains of up to 19%.

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Sebastiaan Schalkwijk, CEO and Co-Founder of SolarSub, said: "I'd like to thank all of our investors and supporters for backing us as we move into the next stage of SolarSub's development. It's been great to see the technology progress from the early days of research at the University of Edinburgh to the point where we're now preparing for larger-scale trials and commercial deployment."

James Taylor, Co-Founder and COO of SolarSub, said: "I am immensely proud of the team in getting to this point. This investment allows us to move from successful technical validation into the next stage of real-world deployment. Our focus will now shift to demonstrating the technology at increasing scale and building out our commercial adoption with industry partners."

Joshua Armistead-Wood, Investor at Sustainable Ventures, said: "The challenge of energy generation is one that, unsurprisingly, remains at the top of our agenda, particularly at a time of increasing price volatility. The solution the SolarSub team is developing stood out to us because, instead of trying to reinvent the wheel, they are focused on one simple root of inefficiency within existing solar systems: excess heat. We have been impressed by what the team has achieved to date and are excited to work with them as they deliver the next stage."

Derek Shaw, Director Company Funding & Investment at Scottish Enterprise, said: "Our investment in SolarSub Ltd underscores our commitment to creating an internationally competitive energy transition industry in Scotland. By supporting ambitious companies in areas such as clean energy technology, we can help them drive innovation and capitalise on the significant economic opportunities linked to the shift from the production and consumption of fossil fuels to sources of renewable energy.

Initially, the company will focus on the floating solar market — where access to water supports effective passive thermal management — before expanding into the wider utility-scale solar sector.

SolarSub has collaborated with organisations across the solar, utilities and research ecosystems and is advancing additional validation programmes in the UK and overseas.

The funding will also help build out SolarSub's engineering team as it prepares the technology for manufacture, certification and commercial deployment.