Can I get paid for exporting excess solar electricity?

Generally no. Standard export payment schemes usually require an MCS-certified installation, which DIY plug-in solar kits do not provide. You can typically only earn money for exported power if your energy supplier specifically supports non-MCS plug-in export tariffs, or if you already have an existing MCS-certified solar setup with registered export metering. Otherwise, any excess electricity fed back into the grid is uncompensated.