Shares of Energy Focus, Inc. (Nasdaq: EFOI) are rocketing after the energy-efficient lighting technologies company, formerly known as Fiberstars, Inc, said it will install its downlight system in a Wal-Mart Super Center and a Sam's Club in Cabo San Lucas, Mexico.

“By using our highly efficient lighting system, these Wal-Mart stores can expect to see significantly lower energy, maintenance and cooling costs over fluorescent, incandescent, and other traditional lighting technologies,” said Energy Focus CEO John Davenport.

According to the U.S. Department of Energy, lighting is the biggest energy expense for retailers, accounting for 37% of total energy use in retail buildings and more than 22% of electricity costs for the average grocery store.

The two Wal-Mart stores are part of Wal-Mart de Mexico, which includes 122 Super Centers, 78 Sam's Clubs and employs 142,000 people across the country. In 2005, Wal-Mart de Mexico net sales increased 13.7% to $15.4 billion.  

Shares of Energy Focus (EFOI) gained $1.30, or 23.21%, to $6.90 in midday trading.