What facts can you share about solar power?

In a small town in England, where it rains with alarming frequency, the government is installing solar panels on the roofs of council homes (essentially government-funded housing for those that may not be able to afford proper living conditions.) There must be a reason why the government would invest the funds to install these solar panels.

Would these homes need to be connected to “the grid” in order to gain any financial benefit for the government to do this? Does the amount of power generated go down when the weather is usually hazy or raining? Basically, I want to know if the local council is mad or being financially savvy.