SolarCity’s shares drop as fourth-quarter losses pile up by Tom Huddleston, Jr. @FortuneMagazine February 18, 2015, 5:48 PM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons SolarCity, the solar power systems company founded by Elon Musk and his cousins, met Wall Street’s expectations with a 52% bump in revenue in the most recent quarter. However, growing expenses left the company with a net loss of more than $140 million. Here are the key points from Wednesday’s fourth-quarter earnings report. What you need to know: San Mateo, Calif.-based SolarCity posted fourth-quarter revenue of $71.8 million, up from $47.3 million during the same quarter the previous year. However, SolarCity SCTY said increased expenses led to the company posting a loss of $141.4 million, or 4 cents per share, in the fourth quarter after reporting a loss of $39.8 million during the same period in 2013. SolarCity’s net loss attributable to non-controlling shareholders was $1.43 per share. Analysts had predicted losses of $1.27 per share. The worse-than-expected losses sent SolarCity’s stock price plunging more than 5% in after-hours trading. The company’s stock price has fallen more than 20% over the past six months due to declining oil prices, which make alternative energy sources such as solar energy a less attractive option. The big number: The company’s fourth-quarter operating expenses doubled year-over-year, reaching $135 million, an increase led by a 135% jump in expenses related to sales and marketing. The good news is that SolarCity installed a total of 176 megawatts-worth of solar systems in the fourth quarter — that represents a 70% increase year-over-year. The company also added more than 21,000 customers during the period to reach nearly 190,000 total customers by the end of the quarter. SolarCity added more customers in the third quarter (nearly 28,000) — something the company on Wednesday attributed to the fact that the fourth and first quarters are typically the company’s “softest quarters of the year” due to seasonal dips in solar energy production. What you might have missed: SolarCity’s forecast for the current quarter includes expected installation of 145 megawatts of solar panels and as much as $52 million in revenue. In an earnings call Wednesday evening, the company offered assurances that the solar panel factory it is building in Buffalo is on pace to open during the first quarter of 2016. The company has said the factory, part of SolarCity’s ongoing expansion efforts, will eventually produce a gigawatt’s worth of solar panels annually, which would make it one of the world’s largest solar panel plants. The plant’s construction follows last year’s surprising purchase of solar panel manufacturer Silevo for roughly $350 million. That deal signaled SolarCity’s intention to enter the business of manufacturing its own solar panels after previously buying its systems’ panels from a variety of outside vendors. Earlier this month, SolarCity also leased a 200,000 square-foot facility in California that was once home to failed solar panel company Solyndra. The facility will house a new research and development center SolarCity is opening in the wake of the Sileva purchase.