I appreciated this calculation. Although as you show it's unlikely that solar panels represent a net loss in energy, it's still kind of off-putting that, given my local power rate of 5 cents/kWh, I'd have to wait 16 years to make back my money if I buy solar panels to reduce the power I take from the grid. Of course, this results mainly from the government subsidy of residential power, a bizarre policy completely at odds with the same government's exhortations to be "power smart".