Net Present Value

The Net present value of the investment per residential unit in the solar PV project can be calculated [35] using Equation (14):

$$NPV = \sum\_{n=1}^{30} \cdot \frac{S\_n - C\_n + NE\_n \cdot t}{\left(1 + d\right)^n} \tag{14}$$

where,

*Sn* = Savings calculated in year *n*

*Cn* = System cost in year *n*, including capital costs in year 1, operating expenditures and inverter replacement where applicable Table A1 (Appendix A)

*NEn* = Net export or amount of excess generation for which the residential building owner is compensated;

*t* = Rate at which net export is remunerated;

t can be equal to retail rate (r) €0.133 per kWh in case of net metering or t can be equal to € FiT per kWh amount in case of FiT or t can be equal to €0 per kWh in case of where no subsidy applies

*d* = Discount rate (considered 0.55% reflecting mid-range of publicly advertised annual equivalent interest rates on savings account in Ireland).
