Plymouth, Wis.-based energy efficient lighting company Orion Energy Systems filed today for a $100 million initial public offering.

Orion plans to list on the Nasdaq under the symbol "OESX."

The company said it would use the cash raised from the offering for working capital.

Not all the money from the IPO will go to Orion. According to the filing, certain investors are expected to sell some shares. The names of the selling shareholders and the amounts expected to be sold were not disclosed.

Orion, not to be confused with Oakland, Calif., windpower company Orion Energy, makes a high intensity fluorescent, or HIF, lighting system.

In its filing, the lighting company said it had installed its HIF systems in over 1,800 facilities across North America, to companies including General Electric, Kraft Foods, Newell Rubbermaid and OfficeMax

General Electric's GE Capital Equity Investments is one of the backers of Orion, with a 9.2 percent stake. The Clean Technology Fund, Orion's largest principal shareholder, holds 11.3 percent.

Founded in 1996, Orion said its revenue for fiscal 2007 was $48.2 million. Fiscal 2007 was also the company's first profitable year, taking in $600,000 in net income.

The company, which has a 266,000 square foot manufacturing facility in Manitowoc, Wis., said it does not have any long-term contracts with its customers.

Orion said no single customer accounted for more than 9 percent of its revenue over the past 3 years, but that one customer was responsible for 20 percent of its fiscal 2008 first quarter revenue.

Thomas Weisel Partners, Canaccord Adams and Pacific Growth Equities are underwriting the offering.

Orion is using Foley & Lardner for legal advice, with the underwriters turning to Latham & Watkins.