I looked into it about 2 years ago.
The cost for panels to produce 3.5Kwh was about 10,000 Euros. The requirement was to sign up for 15 years with the electricity board and they pay 25 cents per unit generated. You are connected to the national grid with a normal meter and charged the same rates as everyone else, you also have an extra metre which records the amount of energy created by your installation. The two are calculated and the net difference gives you a reduced bill or even a repayment should you generate more than you use.
The grant for installing the system is up to 55% (you still have to pay VAT on the full installation cost, not the subsidised price). The panels are not glass covered in the same way as water heating solar panels and maintenance is very low.
The installation should be on a south or slightly southwest/southeast facing roof or the electricity generation is dramaticall reduced. Also the 15 year/25 cents agreement sounds very good at the moment, with inflation it probably will not look so good in a few years.
Some of the grant is paid by all of us paying electricity bills. If you look at the bottom of your bill you will see a charge just after the VAT element that is a Ren. Energy Charge. This relates to the money the electricity company are paying towards the systems and the power generated.