Trust and estates has long been a sleepy corner of the law firm world, but knowing wealthy people has its advantages, as evidenced by Cravath, Swaine & Moore LLP's work for First Solar Inc. on its $400 million agreement to acquire OptiSolar Inc.'s project pipeline. The parties announced the deal March 3.

True North Partners LLC, an investment arm of the Walton family, owners of Wal-Mart Stores Inc., bought First Solar in 1999. David Finkelstein and Daniel Mosley, Cravath's two T&E partners, do work for the Waltons, and the firm's John Gaffney represented First Solar on its initial public offering in 2006.

As of Dec. 31, the estate of John Walton still held 28% of the company's stock. First Solar's market capitalization as of March 11 was $9.75 billion. Cravath's Erik Tavzel, Stephen Burns and Michael Schler represented the company on the OptiSolar deal. The acquirer did not use a banker.

OptiSolar tapped William Collins and Jack Bodner at Covington & Burling LLP. Collins has long worked for Calpine Corp., where Lisa Bodensteiner was the general counsel before taking the same position at OptiSolar in 2007. The seller used Kevin Genieser, Todd Giardinelli and Paul Leggett at Morgan Stanley.

In a more traditional corner of the energy patch, NRG Energy Inc. agreed to buy Reliant Energy Inc.'s retail businesses in Texas for $287.5 million in cash plus working capital estimated at $111 million on March 2. NRG tapped Mitchell Hertz and Elaine Walsh at Kirkland & Ellis LLP, where Stephen Fraidin is leading a team of lawyers helping to defend the company against a hostile bid from Exelon Corp.

For banking advice on the Reliant deal, NRG turned to Ahmad Masud of Credit Suisse Group, which along with Citigroup Inc. is representing the Prince­ton, N.J., power producer on Exelon. Credit Suisse in turn is using Denise Cerasani at Dewey LeBoeuf LLP.

Reliant used Jeff Holzschuh of Morgan Stanley and Bill Montgomery and Tim Kingston of Goldman, Sachs & Co., with Frank Bayouth and Michael Rogan of Skadden, Arps, Slate, Meagher & Flom LLP on the legal side.