By Jonathan Fahey

AP Energy Writer

NEW YORK — Solar panel installations in the U.S. grew 76 percent in 2012 as the cost of panels and the surrounding equipment continued to fall, according to an annual report by a solar trade group.

The U.S. installed panels capable of producing 3,313 megawatts of peak electricity, up from 1,887 megawatts in 2011, the report said. The panels installed last year will generate about the same amount of electricity over a year as a medium-sized coal plant, enough to power 400,000 U.S. homes.

Wal-Mart, the world’s largest retailer, revealed earlier this month that it has installed solar panels on a dozen of its Ohio stories, including nine in the southwest part of the state.

Solar grew in large part because prices continued to fall. The average cost of a solar system dropped 27 percent last year. Also, financing programs flourished that allow homeowners to install solar on their roofs for little or no money down while paying less overall for electricity.

While helping installers, utilities, and homeowners, the plummeting panel prices have devastated the finances of solar panel makers around the world.

Panel prices have fallen because demand for panels in Europe, which is world’s biggest solar market, has fallen as government subsidies have declined. At the same time, raw material costs have plummeted and manufacturing capacity, especially in Asia, has boomed. This has created a glut in panels that has persisted for the last three years.