It depends on your situation. In the Netherlands it is possible to ‘net’ the taxes for energy produced against energy used, calculated over a 12 months period.
In my own case: I produce less energy per year than what I use. So I use the price including BTW and energy taxes. Even when the net price on the day ahead exchange is somewhat negative, I still want to deliver my solar energy to the grid, since the taxes are still providing ‘income’ for me.
Only when the price including BTW and taxes is negative, then I want to shut down my solar panels, since they will cost me money at that time.
For a detailed discussion on the NL situation you can visit here: Het grote day ahead / dynamische energieprijzen topic. - Themaforum: De Energierekening - GoT
