INDUSTRY INSIGHT
Why solar thermal is finally getting its moment in the sun
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Electrification has become the word that’s defined the energy transition. This has been reinforced in the International Energy Agency’s special report on electrification. Here Christophe Williams, founder and chief executive of Naked Energy weighs up the benefits of the often overlooked technolody – solar thermal
t finds electricity’s share of final energy needs to climb from 23% today to 35% by 2035, and the IEA shows today’s cost-effective and efficient technologies, including solar PV, wind turbines and heat pumps, bring that within striking distance. However, what is not talked about enough is
the unsustainable pressure we’re putting on the electricity grid by entirely relying on electrification. In the next decade, electricity demand is expected
to increase by 30% and the National Grid projects that infrastructure upgrades will cost £90bn by 2031. With debates about AI and data centres getting louder by the day, these numbers will likely grow larger. We cannot rely on the Grid to meet this demand
by itself. Businesses are already waiting years for new grid connections and there’s a risk that the cost of grid expansion becomes too great a burden to the taxpayer. This doesn’t mean we should abandon electrification. The war in Iran highlighted the dangers of relying on volatile fossil fuels. Net Zero is no longer about safeguarding the planet and cutting carbon emissions, it’s a matter of national security and our only answer to reduce bills in the long run. However, we need to be smarter about what we electrify and where other renewable technologies can meet demand directly, we must consider the biggest energy demand: heat. Heat accounts for 70% of UK industrial energy
demand, much of it still met using gas. This is also particularly pronounced in the EU, where process heat accounts for three-quarters of industrial emissions. Net Zero cannot be reached without addressing this question. Currently, businesses are facing a heating
trilemma; they need their heating supply to be clean, reliable and affordable. Gas boilers aren’t clean, and in the wake of geopolitical events, it’s proven they’re not reliable or affordable either. The most common answer to this problem has
been to electrify via heat pumps. They’re certainly cleaner, but they’re not necessarily affordable, given the UK has the highest industrial electricity costs in the world. Heat pumps can be remarkably efficient, but this
depends heavily on how a system is designed. If every unit of heat relies on a constrained grid, businesses remain exposed to network capacity and power prices. Far too often, heating systems are entirely
provided by heat pumps or a boiler, and there’s never a conversation about designing a more
tailored heating system that works for the grid and end-user. It’s against this backdrop where ‘grid-edge’ (aka.
off-grid) technologies like solar thermal become important. It’s received far less attention than solar panels have, as shown by the IEA report that weighs up industrial heat pumps, electric boilers, mechanical vapour recompression and hybrid boiler fleets, but leaves solar thermal out of the toolbox. And yet, it has a big role to play in the journey
to Net Zero. Rather than generating electricity and then converting it into heat, it captures the sun’s energy as heat directly. If a hotel, hospital or factory needs large volumes of hot water, that heat can be produced on-site. Every unit generated this way is one less unit that needs to come from a boiler or the grid. Solar thermal may not always provide all the heat
a business needs. However, we can’t expect heat pumps, boilers or any other technology to solve the entire problem alone. The better question is how to make those technologies work together. Take a building using a heat pump. When
solar thermal is used to pre-heat water before it reaches a heat pump, it makes the heat pump more efficient in two ways. First, the heat pump receives warmer water, so it has less work to do to reach the required temperature, improving its
efficiency. Second, because the heat pump uses less electricity, it reduces demand on the grid, particularly at peak times. The same principle works with existing fossil fuel
boilers. For businesses that cannot secure enough electricity capacity for a heat pump, solar thermal can supply part of the heat demand and reduce gas consumption. The future of heat decarbonisation is not about
one technology winning. It is about designing the right system for the demand and using each technology where it works best. This is the future of Net Zero, and we’re at
a tipping point with this thinking becoming mainstream, as shown by GB Energy’s first major investment into solar thermal at £8.875m, alongside Barclays Climate Ventures. Public backing from such an influential body matters: it signals where they see strategic value and industrial potential. The energy industry knows we can’t get to Net
Zero just by producing more clean electricity, but that we need to think more holistically. Generating heat at the point of use with solar thermal does not eliminate the volatility of global energy markets, but it drastically reduces businesses’ exposure to them. When integrated into a sophisticated system design, it also greatly increases the control businesses have over their bills. The IEA is right that the future of Net Zero will still
be led by electrification. But it’s not the only player in the story anymore. The way forward will be based on integration, and solar thermal has a big part to play.
30 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2026 Read the latest at:
www.bsee.co.uk
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