1/5 aint half bad...
...when you consider another energy story today about wind power generation not being able to provide a sustained energy source - surely this tech can take up the slack for that, when the winds die down throughout europe!
But yes the UK would probably see a very small fraction, perhaps 1/100th of that sunlight, until we get a lucky summer - this year hasn't been all that bad - I've got my dinky experimental 2.4watt solar panel powering a small 12v computer case fan permanently blowing into my dining room!
But the thing stops spinning as soon as the thinnest sliver of cloud covers it up.
I reckon it'll take about 10 or so large car batteries with some serious solar panel surface area (costing thousands in all) to even have the slightest chance of running my electrical needs.
Even boiling a kettle will take serious amounts of energy, and probably kill the batteries with its fast drain rate.
Lets not forget these curtains dont work without somewhere to store the energy - much more costs, less reason to come off the national grid!