Building DIY Gardening

Like many households in Britain, we have received leaflets through our door about fitting free PV (photovoltaic) solar panels, with free use of the generated electricity.

Solar PV from Building DIY ebook

This sounds too good to be true as even a small system can cost well over £10,000 so what is the deal? Is it a scam? How does it affect your house and mortgage?

The deal is this: a company (there are a few doing this, with varying standards) will buy and install a large grid of solar PV panels, typically 12 or more, onto your roof if suitable.

The panels will generate electricity (electrons) when receiving light (photons) from the sun (an action first postulated by Einstein in 1905, as an explanation for the photoelectric effect previously ‘discovered’ by Heinrich Hertz in 1887).

Solar PV fitting by the Green Home Company, who are accredited

How does it work – financially

So how does this work financially? What are the benefits to you and to the company?

The solar PV panels will generate electricity. Some is used ‘live’ in the house. However a lot of electricity is used in the evenings and night, when it is dark, so the actual percentage of ‘live’ electricity from the panels will be smaller than your actual overall electricity use. So you will still get electricity bills.

The company gets the excess electricity that is sent back into the grid. The Government has a new (April 2010) Feed In Tariff (FIT) scheme which means they make the energy supplying companies (like EDF, or First Utility etc) pay a set amount for any electricity put back into the grid, at a set rate that is over the market value. This could have been done 10 years ago by the supposedly ‘green’ Labour Party but was not… to busy spending money on other things.

The company is renting a large part of your roof space and has a 25 year lease. That will add complications if you want to sell your house, although they claim mortgage companies do not mind. I would like to see some actual examples of people selling their houses with this fitted. It might not annoy the mortgage company or their solicitors (although they are very picky), it might deter buyers, or it might encourage buyers. Generally, you are giving up rights to part of your house for a smallish return.

This FIT scheme is to encourage people to fit solar panels. It is the European model, used a lot in Germany, where people cover their house and gardens, in solar panels to get a profit from the FIT rate.

So the installing solar company make this profit from excess electricity that is fed back into the grid.

Now, this is easily the majority of the electricity generated, as the panels will be producing the most energy in day time and summer days when no lights or heater are on in the house. Also in the winter when an electric bar or convector heater might be used to warm up rooms, the panels will be least efficient and producing less electricity – so you will still be using grid (pay for) energy.

You will definitely save on your electricity bills, the companies claim up to 50% – but that of course includes 10% or so.

Note: solar panels can’t be fixed to normal slate roof tiles as they damage too much, only clay or solid tiles.

So in brief:

Summer – lots of solar power – no use for it – excess energy goes to the grid – FIT money goes to the installing Company
Winter – hardly any solar power – lots of use for it – no excess energy – no FIT either

So over the sunny months, the investment of the installing company does very well, in the winter, it is in hibernation. Of course if the UK was more southerly, the solar input would be more equal all year round.

So you can see how this is quite profitable for the solar company, but not so great for the householder. The solar company is renting your roof space for their profit. You will gain only a small part of the electricity benefit as explained above.

This is obvious once you think about it, as otherwise, why would they buy the expensive panels and go to all the trouble of fitting them and doing all the paperwork etc?

Despite this it still might be a good idea if you are running a home smelting company (or a home office with several computers), if you work mainly in the summer.

See the Building DIY section on Solar Panels and Solar Energy >

Advanced systems include PV-T which is Solar PV and Solar Thermal combined – see our advice >

To save a bit of money by using solar energy to heat water see the Building DIY Solar Thermal panels advice and fitting >

Solar thermal even works in the winter as the new high tech vacuum systems use a temperature difference not absolute temperature to generate heat.