The Ontario Power Authority's (OPA) microFIT program offers the best return on investment for a solar PV system. The current rate for rooftop solar is $0.396/kWh. Compare this to what you pay for using electricity, which is between $0.075 - $0.135 per kWh. This allows for a PV system that pays for itself in 7-10 years (depending on system size and financing), and with payments guaranteed on a 20 year contract (at the fixed rate of $0.396/kWh).
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