Elon Musk-backed SolarCity Corp, the top U.S. installer of residential solar systems, increased the size of its initial public offering but said it expects a lower pricing, a day after an underwriter said the IPO had been postponed.

The company said it now expects to sell 11.5 million shares at $8 each.

The offering is likely to be priced on Wednesday night and start trading on Thursday on the Nasdaq, an underwriter said.

SolarCity earlier planned to sell 10.1 million shares that were expected to be priced between $13 and $15 each.

At the current intended IPO price the solar systems company will be valued at about $585 million, almost half its earlier proposed valuation of nearly $1 billion.

The company said in a filing that existing stockholders would also sell about 65,000 shares. (http://link.reuters.com/xyf64t)

The clean technology sector has suffered some recent high-profile flameouts with the bankruptcies of solar company Solyndra and battery maker A123 Systems.

SolarCity was promoted as the most promising alternative energy IPO candidate since the debut of Musk's electric car company, Tesla Motors Inc, in 2010.

Technology entrepreneur Musk is SolarCity's chairman and the first cousin of its co-founders, Lyndon and Peter Rive. He currently holds a 31 percent stake in the company.

SolarCity, whose revenue has more than quadrupled in the last five years, allows customers to lease its product by paying a monthly fee instead of an outright purchase. It also benefited from a sharp drop in solar panel prices.

The San Mateo, California-based company reported a net loss of $80 million on revenue of $103.4 million for the nine months ending September 30, 2012.

Google Inc and U.S. Bancorp have helped finance some SolarCity projects, but investors said that determining an IPO price was challenging because there are few publicly traded direct competitors with which to compare it.

Underwriters picked for the IPO include Goldman Sachs, Credit Suisse, and Bank of America Merrill Lynch.