Yes it looks like it would work, on cold sunny days.
Unfortunately in the UK much of our winter is cloudy which would greatly reduce its effectiveness.
yes it would work. just not very efficiently, black absorbs light and doesnt reflect it, and absorbed light turns into heat, personally i'd get a bunch of lenses and fit them to focus on a single copper pipe, which would heat water very efficiently, could use it to turn turbines or to simply have hot water, nice n easy, and a good use for all the speccy kids you hated at school who are now dead cause they arent preppers xD
Built one a couple of years ago, but instead of cans used an old metal radiator.
On a sunny day, pointed directly at the sun all day, had enough hot water to wash and brush up after work.
Most days though it was lukewarm water out.