Some companies offer to install photovoltaic (PV) solar electric panels on house roofs for free, providing the owner of the house with free electricity. This may sound "too good to be true", but in countries like Germany, where Feed-in tariffs (FITs) for PV panels have been around for many years, the idea of "renting out" a roof for a company to install their solar panels is not uncommon.
Under the UK FITs scheme, the generation tariff (tariff paid for every unit of electricity generated) income from a PV roof in a very good location should be enough for a company to repay the costs of installing the panels and make a decent profit - even when the electricity is given away for free (see How much will a domestic PV system earn?). Companies will only generally offer an installation like this on the best sites, where they can recoup their investment in a reasonable time.
For a home owner who can't afford the up-front cost of a PV roof, this could potentially be an attractive option to turn (south-facing) roof space into free electricity.
On the other hand, it is important to remember that it can be financially more attractive to buy your own PV panels. The savings you get from a 3kW (about 20 square metres) PV roof owned by someone else might lead to savings of between £100 and £150 per year, so perhaps two to three thousand pounds over 20 years. However, if you pay for the installation yourself and so receive the full FIT income, then your total income and savings over 20 years may be about £8,000 from panels which cost about £6,000 - so much more financially beneficial to you in the long term.
A Which? survey suggested that it was far more profitable to take out a loan to cover the cost of the panels (e.g. extend a mortgage) and claim the FITs yourself than to go to one of these companies. You can use our Solar Calculator to see roughly how much you could earn from a PV scheme if you pay for it yourself.
If you are considering to take up an offer for free PV panels, you need to take a very careful look at the conditions of the offer to avoid problems later on. The questions below were taken from a document produced by Consumer Focus (a body that has since been abolished and absorbed into Citizens Advice) and run through some of the things you should ask before signing a contract for free PV panels.
You can also see some feedback and advice about free solar roofs on some of the blog entries on the http://www.yougen.co.uk website.
Ownership and maintenance
Change in property ownership
Finally, as mentioned above, not all UK home owners will be able to benefit from such offers. As companies will try to maximize their profits, they will target the roofs with the lowest costs (i.e. easy access for installing the panels) and highest electricity production (south-facing roofs in sunny parts of the country - see Is my home a good site for PV panels?)