City Market/Onion River Co-op is going solar. The Burlington market will begin installing 154 solar panels on its rooftop beginning in January.

How much power do 154 solar panels produce?

If you're a Burlington house, they'd power you and five neighbors for a whole year. If you're City Market, they'd power 3 percent of your yearly energy needs.

That might not seem like a lot, but as the Co-op's Chris Lyon points out in this month's "Onion Skin" newsletter, "Grocery stores are full of energy gobbling refrigeration and freezers." Just think of the heat lost from the front doors sliding open and shut to the frigid air outside all day and night. That's a lot of juice.

City Market recently struck a deal with White River Junction-based groSolar to install the rooftop solar array. Once installed, the panels will generate 33,264 kWh of electricity each year — enough to satisfy roughly 3 percent of the Co-op's total yearly energy usage of 1,100,000 kWh.

By comparison, that's enough to power six Burlington homes for an entire year, assuming each home uses the average of 5,520 kWh.

This isn't just one more feather in the cap of Burlington's most eco-friendly supermarket — it's a shrewd business decision. City Market will use the panels for "net metering," which means they'll be selling power back to the grid. The Co-op will get a 13 percent return on the investment and have the whole solar installation paid back in five years, predicts marketing manager Nicole Fenton.

The panels will cost $187,912, but the Co-op will only pay a portion of that thanks to state grants and federal tax breaks for solar installations.

The Co-op secured a $53,900 grant from the Vermont Clean Energy Fund (part of the American Recovery and Reinvestment Act, better known as "the stimulus package"). City Market is also eligible federal tax credits worth $40,204 — bringing the co-op's total out-of-pocket cost for the panels to $93,808.

Click here to read an interview from this week's Seven Days with groSolar's cofounder and CEO, Jeff Wolfe, who was in Copenhagen last week for the U.N. Climate Change Conference.