I'd be extremely wary of any company that claims to be able to calculate potential energy savings down to the last penny! Those figures of £5,907.15 and £16,708.85 look like they've been plucked out of thin air to me!
Further, scam companies in the solar sector (and there are many!) seem to be run by people who've been involved in several such companies before and who often hold directorships of many other companies as well.
The guy behind Project Solar UK Ltd is Simon John Peat, who was appointed as director of the firm on 18 June 2012, a year after the company was set up. (It was created by another guy whose main business interests seem to be in the leisure and catering sectors, such as running an Indian restaurant, which doesn't suggest a great deal of trade expertise in the solar sector to me).
However, somewhat mysteriously, Mr Peat resigned as a director just one month later, on 17 July. Even more mysteriously, he was then reappointed as a director on 1 September of that year, only to resign again just two days later on 3 September. He was then re-appointed as a director on 1 July 2013.
Mr Peat has previously been a director of Project Energy Distribution Ltd, Fun Power Renewable Ltd, Project Solar UK (North) Ltd, Project Better Energy Ltd, Project Energy Distribution Ltd and Bevan Construction Services Ltd, all of which have been dissolved.
As well as his directorship of Project Solar UK Ltd, Mr Peat is also currently a director of Social Energy Ltd, Clearview Property Ltd, Eco Energy Works Ltd, Curv360 Ltd, Project Better Energy Ltd and Project Solar UK Group Management Ltd.
All of that starts far too many alarm bells ringing with me; I certainly wouldn't have anything to do with company.