If you are thinking about putting solar panels on your roof - to help save the planet, or to get your hands on the absurdly generous subsidies that are being handed out - you could do worse than look at the example of Prince Charles.
He has just got planning consent to put 32 panels spread over 132 sq ft on the roof of Clarence House on The Mall in Central London - at a cost of £30,000.
These should produce about 4,000 kilowatt hours of electricity a year to help power and heat the 19th Century building.
The figure is equivalent to the energy used by an average family household each year and any surplus the Prince generates will be sold to the National Grid for 43.1p per unit of energy produced. What Prince Charles did not do, it is worth noting, is accept an offer from one of these new companies that will stick the solar panelson your roof for 'free'.
Generous: High feed-in tariffs mean panels pay for themselves in ten years
This means you don't have to pay the typical £12,000 to £15,000 up-front costs of fitting the panels to an average-size house.
The attraction is that you get perhaps £230 worth of 'free' electricity a year for some disruption, but you could be signing away as much as £35,000 worth of feed -in tariff (FIT) revenue over the next 25 years.
This is the potentially vast income the companies are after, which is why they have sprung up like ragwort since the feed-in tariffs came in on April 1.
The taxpayer-funded subsidy is estimated to cost between £6.7 billion and £8.4 billion over 20 years unless, as has happened in Germany and, last month, in Spain, there is a drastic rethink and the tariffs are cut back.
The most dubious part of the scheme is the generous subsidy for solar panels: while households with these receive FITs of 43.1p, large wind turbines and hydro plants earn FITs of just 4.5p, yet are far more productive and better suited to the UK climate.
'Those who hate environmentalism have spent years looking for the definitive example of a great green rip-off. Finally it arrives, and nobody notices,' says environmentalist George Monbiot, who favours wind farms and nuclear power over generous payments for DIY energy creation.
The Right-wing Taxpayers' Alliance is equally scathing about the scheme, which is a key part of the UK's commitment to cut carbon emissions and hit an EU target of generating a fifth of energy from renewable sources by 2020.
Since April 1, 8,618 microgeneration installations have joined the scheme, of which 8,143 are solar panels.
Whatever the scheme's flaws, the cash is being offered, so there is no reason at all why you should not hold out your hand.
'Free' panels from the likes of ISIS Solar, HomeSun, A Shade Greener and soon many others - set up by rag-trade millionaires and even the odd hedge-funder - offer a superficially attractive deal, but there are drawbacks.
They are interested only in the right sort of roof, which means Grade I listed Clarence House would probably have been turned down. Large, south-facing roofs in good condition with no trees or telegraph poles nearby are the most attractive, and the favoured locations are the South East and large conurbations.
But the deal means you lose out on feed-in tariff income that could be worth £900 to £1,450 a year, guaranteed for 25 years.
So if you have a suitable roof, you could raise the £12,000 to £15,000 yourself, remortgaging at typically five to six per cent, and paying off the cost of installing the panels within ten years.
Most households are likely to make a risk-free profit of £20,000 over the 25 years while enjoying lower electricity bills.
It is vital to be aware of the small print and be clear that the panels are properly insured to last 25 years. Also, ponder the effect on solar panels of the autumn gales in the UK that in the past have stripped barn roofs.
There have also been cases of housebuyers insisting vendors remove solar panels, either because they are unsightly or because the new owner doesn't want to risk a leaking roof.
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