SAN MATEO -- SolarCity's first earnings report as a public company was a disappointment Wednesday, as the solar installer posted losses that more than doubled analysts' forecasts and saw its stock price descend.

The San Mateo-based solar installer posted a fourth-quarter loss of $3.04 million, or $1.10 cents a share, compared with net income of $3.7 million, or 24 cents a share, a year earlier. Analysts had expected a loss of 49 cents a share, and SolarCity's shares were down more than 9 percent in after-hours trading. For the full year 2012, total revenues were $128.6 million, up from $59.5 million in 2011.

SolarCity said it signed up 30,950 customers in 2012, up from just 9,034 in 2011. The company now has more than 50,000 customers in 14 states and 287 megawatts of solar power installed.

"We plan to have 250 megawatts deployed in 2013," CEO Lyndon Rive said in a conference call with analysts. "Solar is still less than 1 percent" of electricity generation. "It's a massive growth opportunity."

Founded in 2006, SolarCity is one of the nation's leading installers of rooftop solar panels on homes and commercial businesses, including more than 140 Walmart stores nationwide. It made its name in the solar industry for pioneering the concept of "no-money-down" leasing and arranging third-party financing through leading banks and companies, including Google (