Evoenergysolutions 

I inherited my solar panels when I moved here 2 years ago. I was contacted by EVO a few months ago and took up their offer of an all inclusive Maint contract for £19.99 a month. Good job I did as my system stopped working a few weeks age. It took a few phone calls and I get the impression that their office systems Ahemmmm need working on. However a couple of engineers arrived today and a new inverter fitted which would have cost me over £500 so happy bunny here.

well known scam. Inverters do NOT need servicing

This company are still sending out unsolicited mail offering existing installations an MOT. This opens the door for them to "discover" issues that may or may not exist and charge for the work.
This report was issued by the MSC about this company: Consumer alert: EVO Energy Solutions. MCS have been made aware that unsolicited letters are being circulated, targeting consumers with Solar PV systems. Letters have been distributed from a company called EVO Energy Solutions offering “free MOT and services” on systems. ... EVO Energy Solutions are not registered with MCS.

Contacted by letter offering me a free solar panel system MOT and service. This is usually followed by an offer to install an inferior inverter from an unknown Chinese company with dubious warranty at considerable expense.

If your inverter breaks you can get it fixed or buy an new one from a reputable supplier. There's no need to replace an inverter that's working perfectly well!

Most inverters will continue working properly years after the warranty had expired.