Edinburgh-based SolarSub raises £1.3m pre-seed led by Sustainable Ventures with Zinc VC
This article covers SolarSub, an energy startup spun out of University of Edinburgh research, which has raised £1.34m in a pre-seed funding round to develop and validate a passive cooling system for photovoltaic modules. The funding will support engineering, independent testing and larger-scale trials aimed at increasing energy yield and reducing heat-driven degradation, with an initial focus on floating solar installations.
SolarSub, an energy startup spun out of University of Edinburgh research, has raised £1.34 million in a pre-seed funding round to develop and validate a passive cooling system for photovoltaic modules — a technology aimed at increasing energy yield and reducing heat-driven degradation in solar arrays. The funding will support further engineering, independent testing and larger-scale trials, with an initial focus on floating solar installations where proximity to water aids passive thermal management.
Why it matters
Solar panels lose efficiency and suffer faster degradation as operating temperatures rise, a persistent problem for utility-scale and floating solar projects in hot climates. Improving thermal management without adding complexity or operating costs could raise lifetime energy output and strengthen project economics. Early test results suggest the approach can deliver meaningful gains under high-temperature conditions, which matters as developers and investors seek ways to maximise returns from existing solar assets and new deployments.
Inside the product
SolarSub is developing a passive cooling module that requires no pumps or moving parts. The system aims to keep panels closer to optimal operating temperatures, limiting temperature-driven performance loss and material degradation.
Independent trials cited by the company found energy uplifts of up to 17.5% at the University of Edinburgh’s FloWave ocean energy research facility and peak gains of up to 19% during outdoor testing at Heriot-Watt University’s Dubai campus. SolarSub says it is progressing validation programmes across the United Kingdom and internationally and plans to scale engineering capabilities for manufacture, certification and commercial deployment.
The company — founded by two University of Edinburgh engineering graduates — is initially targeting the floating solar market, where direct access to water provides a natural environment for passive thermal management, before expanding into the wider utility-scale solar market.
Who are the investors?
The round was led by Sustainable Ventures and includes participation from Zinc VC, Scottish Enterprise, Old College Capital, SFC Capital and the British Business Bank, with additional backing through Innovate UK’s Investor Partnership programme. The funding package combines private venture capital and public innovation support intended to move SolarSub from technical validation to larger real-world deployments.
In the announcement, 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.
In the announcement, 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.
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Founder perspective
In the announcement, Sebastiaan Schalkwijk, Co-founder & CEO at 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.
In the announcement, James Taylor, Co-founder & COO at 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.
The bigger picture
The SolarSub raise highlights continued investor interest in efficiency-improvement technologies across solar markets, including floating solar where new capacity is being added in the UK and overseas. The combination of university-led research, targeted public backing and venture capital here illustrates a common pathway for UK clean-energy ideas moving from lab to commercial trials.
If SolarSub’s performance holds up in larger deployments, the approach could offer a relatively low-complexity retrofit for improving yield and asset longevity — a pragmatic option for developers seeking incremental gains in project economics. For the UK and European energy ecosystems, this round is another sign that investors and public bodies remain willing to back technologies that squeeze more value from existing renewable capacity while supporting exportable clean-tech solutions.
They've invested in SolarSub
Get to know these energy investors
| Investors | Investment Focus | Startup Investments | Round Size | Connect |
|---|---|---|---|---|
 Sustainable Ventures( ) | ||||
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 Scottish Enterprise( ) The firm focuses on supporting early-stage and growing companies in Scotland, of... Glasgow  | ||||
 Old College Capital( ) Old College Capital (OCC) is the University of Edinburgh’s venture investment fu... Edingburgh | ||||
 SFC Capital( ) SFC Capital is a venture capital firm that focuses on investing in early-stage t... London | ||||
 British Business Bank( ) The British Business Bank focuses on enhancing finance accessibility for smaller... Sheffield | ||||
 Innovate UK's Investor Partnership programme( ) | ||||
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