The cost of running sufficent artifical lighting to generate enough wattage to cover the costs of that lighting..(not to mention the planning permissions) would not make it financially viable.
Huh? I was referring to the government in future years changing the payback scheme. ie: So it's not at the current (high) rate.
I was making the analogy with public sector pensions etc, where people were expecting a rate (pension) but are now having their schemes changed due to how impractical they have become in later years.