There are various ways to optimise existing Solar panel installations thus increasing your return on investment.
Do you have a hot water cylinder?
By adding an Immersion controller to your system any solar electricity, you aren’t using that would normally be exported to the national grid, can be rediverted to heat your hot water.
By installing a battery storage solution, you can store the solar energy that would normally be exported to use on an evening and during a power cut.
Is there shading to one or more of your panels?
Conventional systems are wired in series, meaning your solar panels work as a team, if one of your panels is slightly shaded, then it will affect the performance of all the panels in that string. By adding a power optimiser to the affected panels that panel would then work on its own merit and not affect the performance of its team mates.