Mahon thinks that within a couple of years, PV will produce electricity at about US$0.10 a kilowatt.
"That's pretty competitive," he says.
Figures from Chris Davenport, at energy consultants McKinnon & Clarke, show that fossil fuels typically produce electricity at between around US$0.04 and US$0.08 a kilowatt hour in Britain, whereas wind is around US$0.11/kWh.
Solar thermal, which heats water, comes in at an average US$0.13 and solar PV at around US$0.29/kWh.
Biofuels, though, are less than US$0.08/kWh.
Jeremy Leggett, head of PV firm Solar Century and author of the book Half Gone, which predicts that oil will soon run out, said PV prices are quickly dropping.
"With manufacturing costs falling 20 percent every two years in solar PV, and the price of oil hooked to the cost of gas, and coal transportation, we can expect the falling cost of solar electricity to cross the retail price of polluting power in most industrialized markets within just a few years now. Huge as the investment into solar now is, it is going to rise further as the opportunity dawns on ever more people," Leggett said.
Ian Simm, head of Impax Group, Britain's largest green investment fund, says rising oil prices boost simpler products like home insulation and energy-saving devices, particularly for those who run central heating on heating oil.
"Energy efficiency is most obviously linked to the oil price. This is what people need to do first as it is an economic win irrespective of the price of carbon. Loft insulation now has a payback time of just one year," Simm said.
Mahon cautioned, though, that higher oil prices also gave an incentive to oil companies to explore and produce more of the stuff as well as processing coal into liquid fuel, something which is highly polluting.
"But higher oil prices will also create enough margin to allow people to develop dirty technologies, but in a clean way using carbon capture and storage," he said.