ZESTEC RENEWABLE ENERGY: Unlocking Renewable Opportunities, Capex-Free
Zestec Renewable Energy is becoming a significant green power producer in the UK, positioning solar on rooftops and carports, owning and operating systems, while selling power back to building owners and tenants over a longer period. The company’s model allows for clients to embrace decarbonisation with zero capex and is proven across many high-profile projects.
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Interview with Simon Booth, CEO
Zestec Renewable Energy was already a business with momentum when Energy Focus profiled the company in late 2024. At that point, the UK specialist in funded commercial solar had established itself as one of the most credible operators in the behind-the-meter renewable market, pairing technical delivery with long-term Power Purchase Agreement (PPA) financing. 18 months on, that momentum has accelerated alongside client demand for energy security and affordability.
Backed by funds managed by Octopus Energy Generation, Zestec has continued to expand its footprint across some of the most recognisable commercial and industrial estates in the UK, building an increasingly varied portfolio that stretches from logistics hubs and manufacturing facilities to airports, visitor attractions and nationwide retail estates. The company’s fully financed model, under which clients receive energy benefits without the upfront capital burden, remains the cornerstone of that expansion and is increasingly proving to be one of the most effective routes for organisations seeking energy resilience.
“Business has continued to be really positive over the last two years,” says CEO Simon Booth. “We have a whole mix of projects and that is exciting.”
That breadth is now one of Zestec’s defining strengths. Booth points to international airport projects in England and Scotland, where construction of significant ground mount schemes will improve flexibility. At LEGOLAND Windsor, the company has recently energised a 1.4MW solar carport, adding to a project that already drew industry attention through Zestec’s collaboration with Mitie. Alongside that sits a completed 4.4MW rooftop installation for Leggett & Platt and an advancing nationwide rollout with Co-op that could ultimately touch hundreds of sites.
“We are now far into a rolling programme with Co-op across their portfolio in the UK, and that has been a very good multisite project for us,” Booth says.
For the CEO, volume is as equally important as visibility. The businesses now choosing Zestec are among the most operationally demanding in the country, and they are partnering because certainty has become commercially valuable. Airports, retailers and manufacturers are no longer viewing on-site solar as a sustainability gesture; they are treating it as infrastructure.
That shift has landed in exactly the market Zestec was built to serve. While established EPC providers continue to crowd into the solar space, many still offer only installation through a traditional sales structure. Zestec offers ownership, funding, operational management and long-term performance accountability in one package. Every project is financed through Octopus, while Zestec manages the delivery and lifetime oversight.
Booth is clear that the company’s approach has become more relevant as the industry evolves. “We have seen more entrants coming into the market and people are seeing great opportunities in the renewable sector. Smaller providers are migrating from other technologies and looking to offer solar as a complementary technology.”
Beneath that growing competition sits a tough commercial truth: customers are looking for partners that can stay with an asset for 20 years, not simply install it and leave.
GROWING VALUE
The economics are increasingly difficult to ignore. Research from the University of Surrey has reinforced what the global renewable sector has been arguing for some time: solar is now the cheapest source of electricity in the world. The International Energy Agency continues to identify solar PV as the dominant engine of renewable deployment globally, with investment and capacity additions outpacing every other technology class. Against that backdrop, the commercial case for on-site generation has shifted from attractive to urgent.
Zestec has 15 years of experience in finance, design, construction, and maintenance.
“Everything is fully funded by Octopus and we manage the delivery process, working with our approved installation partners,” Booth explains.
“We recently finished a project in the UK northeast where we put in a solar carport, solar on the roof, and then EV chargers – a holistic energy solution. We are seeing more demand for that as it is a real opportunity for clients.”
Capital remains one of the biggest barriers for commercial and industrial occupiers. Businesses may understand the savings case for solar, but they are reluctant to divert working capital from core operations into rooftop or land-based generation assets. Zestec removes that tension entirely. The client buys cheaper power through a long-term PPA, while Zestec retains ownership and operational responsibility.
It is a deceptively simple proposition, but one with increasing relevance in a period where macroeconomic caution still shapes boardroom decision-making. Inflationary pressures, volatile raw material costs and a fragile geopolitical environment have all created hesitation across the built environment.
“Without a doubt there has been upward pressure on pricing,” says Booth. “We are not expecting decreases across any part of the supply chain through 2026 and 2027.”
That reality has lengthened sales cycles. Even with no-capex solutions, clients are taking a more measured view of commitments. Yet Booth suggests this has strengthened, rather than weakened, Zestec’s customer relationships because the company has leaned harder into transparency.
“We have always tried to be very open and transparent with customers,” he says. “Working with clients, walking them through the underlying assumptions from the outset, and then showing any movements as we go through the development phase is something that we have seen as valued by clients.”
For a business built on long-term PPAs, trust is not a sales tool; it is a prerequisite. Booth is clear that Zestec is not simply selling hardware. It is underwriting energy outcomes over decades. That changes the diligence and the modelling of every decision.
“We are trying to understand customer objectives when it comes to managing energy and carbon,” Booth says. “Whatever claims we have made to a customer, we have to make sure it is delivered because, for us as the investor and owner of the asset, we might not achieve the returns we need. When you are the long-term owner and operator for 20 or 25 years, it has to perform.”
That owner-operator mindset is increasingly differentiating Zestec from transactional installers. The company is not motivated by the fastest margin; it is motivated by lifetime asset return and customer retention. As a result, technology is introduced where it makes commercial sense, not where it creates the biggest upfront invoice.
Booth points to battery storage as an example of where market enthusiasm can outrun practical application. “We are certainly seeing a good case when planning solutions for clients to include BESS, but it is not mainstream and it remains a niche business case.”
Solar, by contrast, remains the proven entry point because its economics are now immediate, understandable and bankable.
MARKET SHIFT
The consequence is that Zestec’s customer conversations are becoming broader and more strategic. Longstanding relationships, especially with major brands, are evolving beyond standalone rooftop arrays into integrated energy planning.
“Our relationship with Amazon stretches back five years and we see it as an important, strategic relationship in the UK,” says Booth. “We are looking at how we can incorporate energy storage and EV charging into existing schemes that we have developed for them.”
That kind of progression shows that funded solar is no longer a one-off intervention; it is becoming the foundation layer for wider decarbonisation infrastructure.
The same principle is appearing across newer projects. Carports are emerging as a particularly active area, giving clients another route to productive generation where roof space is constrained.
This widening of the addressable estate is important because one of the old misconceptions around commercial solar was that only owner-occupied, structurally simple buildings could participate. Zestec has spent years dismantling that assumption.
“A large part of the market is tenanted and the solutions are just as applicable for the tenants as they are for the owners,” Booth notes. “It’s a misconception that funded solar doesn’t work for tenants as well as it does for owners, but it absolutely does. For example, Amazon does not own the buildings on which we have worked, and they have reaped real rewards.”
That opens the market dramatically. Britain’s commercial property stock is heavily tenanted, fragmented and often capital constrained. The ability to finance generation without requiring occupiers or landlords to write a large cheque is precisely what turns latent demand into executable projects.
PARTNERSHIP PUSH
The next chapter in the company’s growth may be even more consequential than the solar arrays themselves.
At the start of 2026, Zestec signed an exclusive partnership with Kingspan aimed at solving one of the most persistent blockers in commercial rooftop deployment: ageing roof condition. For years, many viable solar prospects have stalled because buildings required refurbishment before panels could be installed, and clients lacked the capital or coordination framework to tackle both.
Zestec and Kingspan have now created that framework, combining funded solar and roofing works into one integrated commercial proposition.
“Having operated in this space for 15 years, we have seen an increasing number of situations where we talk to clients about rooftop solar and one of the key challenges is the condition of the roof,” Booth says.
The answer was to merge Kingspan’s global roofing pedigree, including its exciting new PowerPanel products, with Zestec’s funded energy expertise.
“We signed at the start of 2026,” Booth explains. “We are helping both the solar market and the roofing market to access the opportunity where there is demand but where there hasn’t previously been a financing mechanism that would enable this.”
That may prove to be a defining development not just for Zestec, but for the wider UK clean energy retrofit market. Commercial building owners are under simultaneous pressure to improve asset performance, cut emissions, strengthen roof integrity and manage energy costs. Historically those have been treated as separate capex decisions. Zestec is turning them into one coordinated energy investment.
In doing so, the company is moving beyond funded solar provider and deeper into long-term decarbonisation enabler.
At the end of 2024, Zestec was a flourishing business with a bright future. Today, it is a company translating early promise into large-scale execution, attaching blue-chip names to delivered assets and systematically removing the practical barriers that have slowed commercial solar adoption for years.
With Octopus providing financial muscle, with major national projects progressing, and with Kingspan opening an entirely new retrofit pathway, Zestec is not merely participating in Britain’s renewable transition. It is helping define how that transition gets financed, built and scaled.