What about the initial investment in Belfast when it is time to set up a new solar system? In general, the cost is going to vary depending on how many panels are needed but it tends to sit somewhere between €5,000 - €8,000 for PV systems and between €9,000 - €12,000 for PV & Battery systems.
Please note, this cost will come down because of the SEAI grant (€3000) that's tagged onto the investment by the government. Based on current numbers in Ireland, this can end up leading to a significant return on savings over 5 years. After 6-7 years, the investment will have paid for itself and everything else becomes an addition to your return on investment.