As a former "creature" of the oil industry, Jeremy Leggett is well placed to promote greener alternatives. He worked as a consultant for BP and Shell in the 1980s but turned his back on the industry after reading a series of scientific papers that discussed carbon dioxide's role in global warming. To the astonishment of his colleagues, he joined Greenpeace as chief scientist, spending six years of his career fighting his former employers.

Leggett is now in what he calls the "third phase" of his career, as the founder and executive chairman of Solar Century, a company that supplies photovoltaic solar panels to large corporations, house builders and local government. He feels business is at the centre of the climate-change debate. "Governments are not going to solve this problem," he says. "If there is a solution—and the jury is still out on that—it will come from [the] leadership of the business sector intersecting with real concern among consumers."

Businesses like his haven't had much help from the government. In terms of subsidy, he says, they've had "nothing compared to what the nuclear industry has had". The stepping stones, what Leggett calls "short-term market enablement", haven't been laid for them. "It's about pumping technologies when they're in the growth phase," he explains. "What's disappointing about the UK [government] is that they aren't seeing what other governments, such as Germany, Japan and the US, are."

Solar Century has grown steadily since winning VC funding in 2000. A turnover of £30m is projected for this year. Leggett's biggest clients include Tesco and Scottish and Southern Energy, also an investor. "This is the most attractive field of the cleantech investments," he says. "Most people don't understand how potent it is. With the right partner in the construction sector, we could put up zero-emissions buildings within weeks, which would have no electricity bills."

Solar energy attracts as much controversy as it does plaudits. Last month, RICS, the professional body for chartered surveyors, released a report suggesting solar can take as many as 100 years for energy savings to pay back the initial investment in the panels. By Leggett's calculations, "payback" comes after only 13 years. RICS has, says Leggett, apologised—but that hasn't stopped "the high priests of the nuclear club" using it as propaganda.

Leggett defines cleantech as a "survival technology". Solar panels aren't a "magic bullet", he says, but consumers will eventually become sufficiently worried to turn their homes into a standalone power plant. "The lights will stay on, the shower will be warm and they will have done it themselves. That's what's coming in the future."