You don't necessarily need full sun any more (though it helps). Solar panels are a lot better than they used to be at generating power on cloudy, overcast days. You can even use them in the North of Britain these days. Of course they generate more on both of our sunny days, but they still work on our normal rainy cloudy days too.
I remember reading about some plan to fill the Sahara desert with solar panels, which would in theory be able to power the whole world, but I imagine there's a whole lot of politics, profit and greed in the way of something like that ever working (I imagine there's also a tonne of engineering and environmental considerations).
The answer to any internet-related question from that era is "because you touch yourself at night".