That's about 10x the size of mine, so actually not too surprised it's 10x the price!

To have that much solar power on my house in the UK I think I would need to register as a power station, if I wanted to also connect and input to the grid! (Don't hold me to that, it's just anything up to 5kW has a really simplifying process and no planning permissions or needed or anything).

In the UK average houses only really need 2-3kW system, which would basically meet all needs in the summer but not really touch the sides of usage in winter - we get so little sunlight in the winter it's not even worth trying.

It's very, very rare for a residential property to have above a 5kW system.

But then, we don't really use cooling and we tend to use natural gas for heating. So while we only use 10-15kwH of electricity per day, we use a lot more in natural gas for heating over the winter.