Typically a return of between 7% and 14% can be expected on your investment year-on-year with a PV system, which easily outstrips the return that you would expect keeping your money in the Bank.
As part of your quotation, regardless of size, a financial model will be prepared for you, giving anticipated figures for your particular property.
How will it affect the value of my property?
The addition of PV panels will obviously enhance the appeal of your property and make it more saleable, especially for those customers that will be treating the system as an asset on their balance sheets.
The provision of free daytime electricity and a property with an income will obviously prove an attraction for most buyers too, especially in the case of premises with a large electricity demand.