Ours cost $1,700 for a 1.5kW system. We get 50c/kW put into the grid. The first bonus was that TRUenergy completely stuffed up the billing and failed to bill us for ten months, so according to the consumers contract they had to give us the first bill free: +$290 for starters! Since then we have received credits for $401 for 802kWh input to grid, and are owed another $235 on our next bill. As it is dark, I can't find out how much solar power we've used! But in 18 months we've made $636 (excluding TRUenergy's cock-up) so we're probably well on track for a three year payback.
Our bills were about $300/qtr, but we've got rid of the pool since the last bill, so there should be an improvement there. Three teenagers, all electric house (no microwave).
