Re: 566 terawatts a day?
"Solar is a great idea, most roofs are empty with nothing on them, and could easily be built from solar materials, cover every roof in the UK and you would generate all the power we need..."
Lets take this an item at a time:
"Most roofs are empty" - For most roofs, this is a good thing. Most roof structures weren't designed to take the weight of the roof, plus solar panels - let alone the occasional high winds that hit.
"Could easily be built from solar materials" - Given the high price of housing already, unless you can make these "solar materials" as cheap as existing roof materials, not likely. On the flip side, better than putting a roof on a new property then lobbing panels on top. Subsidy is a bad idea in any context - using tax payers money to hide the sins of a questionable idea....
"Cover every roof in the UK and you would generate all the power we need" - except we wouldn't due to the number of south facing roof tops (as you rightly point out), and that UK weather isn't constantly good enough to generate that much juice all the time - particularly in the winter when it's needed most.