Thanks to two All-Sun Trekker solar panels in his backyard, Colin’s new house is electrically net zero – it produces as much electricity as it uses, or more. That’s pretty cool. But what’s even cooler is that Colin got the panels for free. Sort of.

Colin bought the panels from All Earth Renewables. He bought them with a PPA (pre-purchase agreement, or power purchase agreement), which is basically a lease-to-own option. For five years he pays monthly installments back to the supplier, and then he purchases the panels at a much-reduced price.

Doesn’t sound free yet. But the solar panels started generating electricity the moment they were hooked up. That means from the beginning of the lease, Colin has had a new source of income: selling that electricity back to the grid. (To be precise, the electric company subtracts the kilowatt-hours he generates from the kilowatt-hours he consumes, and then either charges him or credits him for the net-meter difference.) The terms of the lease are such that his regular payments more or less equal the value of the electricity he generates. In other words, Colin gets the panels for no out-of-pocket cost (compared to what he paid before), and when he owns them in full they’ll generate pure savings.

I usually write about small houses, but switching to renewable energy is another way to live a lighter and less expensive life. If you don’t have a roof or a yard, you can buy into a solar farm for the same benefit. And with a PPA, net-metering completely offsets the cost to own, and you get your power for free. Why don’t more people do this?