The financial benefits of installing a Solar system include-

Feed in Tariff* currently 4.59p/unit
Export Tariff* currently 4.85p/unit
Cost savings depends on cost of grid electricity
* Feed in Tariff and Export Tariff are index linked and Guaranteed for 20 years. Tariff rates as at 01 April 2016

The amount of Solar electricity produced by a rooftop system will depend on a number of factors such as location (the further South the better), pitch of the roof and direction the panels are facing (South facing is best).

Other factors are shading and of course the quality of the Solar panels and the installation.
As a guide, a typical 50kWp solar system will require 200 x 250kW panels and these will generate up to 57,000kWh of electricity in one year.

This translates into
£2,616.30 – FiT (paid on all the solar electricity)
£691.13 – Export (assume 25% is exported)
£4,916.25 – Cost savings (assume grid electricity is at 11.5p/unit)
£8,223.68 – Total income and savings
400 Tons – Annual savings in CO₂

As a guide, solar installations start at around £1.25/watt. So a 50kW system will start at £62,500 + VAT. This cost includes all installation, commissioning and 10 year warranty. So you can see this provides 13.16% IRR. In addition to the financial returns you save on CO₂ emissions.