There are many variables in estimating a payback period for investing in a Solar PV system. My statement in May was designed to show the change in payback period as a result of the VAT change. A worked example (based on a 4.5 kW system, costing on average €9,000 prior to the VAT change) is as follows :
Assumptions
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4.5kWp system, producing 800kWh per kWp per annum
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Electricity Tariff @ 0.32c per kWh
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80% Self Consumption
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Calculations
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4.5 kWp
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3600 kWh produced p.a
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800 kWh x 4.5 per annum
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2880 kWh self-consumed p.a
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@ 0.32c per kWh
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Saving €921.60 per annum
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Average 4.5 kW System Cost
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Minus Grant €2,400/savings p.a
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Payback Period
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€9,000 (pre-VAT Change)
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€6,600/€921.60
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7.16 years
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€8,000 (post-VAT Change)
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€5,600/€921.60
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6.07 years
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