What happens when I produce more electricity then I'm using?
It's sent to the mains grid or stores a battery.
Any time you produce more electrical energy than you need, it's automatically sent out to the 'grid', unless you have a storage facility of some sort. The grid connection is the set of cables in the road that is supplied by the local 'utility', in Guernsey this is Guernsey Electricity (GE). They are responsible for the 'grid infrastructure'. You get paid for that electricity according to the price set by GE at the time with your solar 'behind the meter' (BtM). If you have a storage system, rather than exporting you can charge during the day and offset electrical power at high rates coincidental to when solar is not operating, such as the early and later parts of the day.