to consider whether such investments represent a good financial decision for firms in Belgium. The authors calculate key financial criteria such as NPV and PBP, taking the tax deductions applicable to PV in Belgium into consideration. The authors also conduct sensitivity analysis to determine the key factors influencing the financial variables. The costs include those for components, O&M, financing and insurance. The revenue stream includes saved energy expenses, and tax deductions and subsidies associated with green energy installations. However, for the example studied, the investment yields a negative NPV and that the payback period is long (between 8.3 and 10.2 years). Kahn and Iqbal [58] consider potential remedies to the problems of stand-alone decentralised energy systems which sometimes make them nonviable options – such as low capacity factors and excess battery costs. The authors suggest that stand-alone systems could be used as a hybrid with other sources of energy carrier (both renewable and non-renewable) so as to increase their cost effectiveness. They use HOMER software to find the optimal combination of energy technologies in Newfoundland. The results suggest that some hybrid systems (such as a wind–diesel–battery hybrid system) are commercially feasible, but that other systems (such as an environmental friendly hydrogen-based hybrid system) are too costly to be commercially viable.