UK Feed-in Tariffs also apply to Commercial installations but the tariffs reduce  as the installations scale up to keep the returns similar.
They  change at 4kWp, 10kWp, 50kWp, 100kWp and 5MWp and the scale of investment goes up accordingly as do the returns.  Realistically sites above 50kWp (about the size of a medium warehouse) are probably not commercially viable.
Check for
  • Corporation Tax relief for companies
  • All the power that is produced, is paid for, whether used on-site or sent to the grid! 
    In addition
    • VAT is only 5% for domestic sales but 20% for commercial. [this may change]
    • Rights can be assigned not just to the property owner – which means the capital can be released if necessary – or that investors can lease suitable roof space.
    • There’s also the potential to take advantage of the market if the price of electricity soars though this probably only applies to the larger scale, lower tariff systems.
    • Landlords can sell the power generated to their tenants.
    Smaller commercial systems mirror domestic ones and outside of conservation areas and listed buildings should not need planning permission. Ask your local planning department. 
    Technically larger systems are not much different to domestic ones except in scale, however it may be worth investing in tracking systems to follow the sun or in more cost-effective less efficient systems if you have the space. 

     Getting British Business Online