The UK government once had a Department of Energy & Climate Change, which no longer exists but has been incorporated into the Department for Business, Energy & Industrial Strategy, which sounds much more environmentally friendly. The former chief scientific advisor to this department, the late Sir David MacKay wrote a book trying to be quantitative about renewable energy, not political, and then gave it away for free online (withouthotair.com). In this book he discusses various uses of energy (heating in Winter, cooling in Summer, cars, TVs and consumer goods, for example), and quantifies the scale required for renewable energy to be an effective contribution to the energy budget of the UK.
Unfortunately the picture painted by the book is not very positive and implies that to become a sustainable country, or even a carbon neutral one (these are not necessarily the same thing) the UK must make an enormous effort now. Unfortunately the book was written almost 10 years ago, and although there has been some progress (before it was dissolved the DECC reckoned the UK was on ~20 % renewable electricity – not ~20 % of energy used was renewable by the way), however government support for renewables has decreased as well.
In 2016 the government decreased the feed in tariff for domestic solar panels (I.e. make electricity not hot water) from 6 – 13 p per unit in 2015 to about 4 p per unit today. There are arguments that solar should not need the feed in tariff (which is essentially a subsidy) as it should be able to stand on its own against traditional large scale power generation facilities, primarily based on fossil fuels.
If this is to be the case (as the current government seems to think) then substantial changes to will need to be made to the technology used and the implementation of the technology. Currently the solar panels that people would buy to put on their roofs convert about 20 % of the energy in sunlight to electricity. This number varies a bit depending on age of the installation, but is actually really good as the fundamental limit on the efficiency for a silicon solar cell (like on the majority of roofs) is 32 %. Prototype silicon cells have been certified at 25 %, but these are a long way off being put on roofs though, and even when they are they will only reduce the space requirement by 20 % for the same power output. This indicates that if we want to get really serious about solar energy there will need to be significant research effort into the materials and manufacturing engineering to bring down the price of existing technologies. It also indicates that additional technologies need to be investigated to try to squeeze as many joules of electricity out of the sun as feasibly possible to meet our future energy needs, as at present solar power only provides about 2 % of the UK's electricity, and the government doesn't seem to want to help us get there.