NEW YORK ( TheStreet) -- Dell's ( DELL) board has urged shareholders to vote in favor of the $24.4 billion buyout offer led by founder and CEO Michael Dell. According to filings with the Securities and Exchange Commission, the board unanimously recommended the offer, which equates to $13.65 a share. In a letter to shareholders, the board said, "A sale to the Michael Dell/Silver Lake group ... is the best alternative available -- in a challenging business environment it offers certainty and a very material premium over pre-announcement trading prices." The letter did not mention a rival $21 billion bid for Dell led by activist investor Carl Icahn and Southeastern Asset Management. The counter offer led by Icahn would let Dell shareholders keep their stake in the company and give them $12 per share in cash or additional shares. Icahn previously vowed to try to convince shareholders to vote down Michael Bell's offer if his own was rejected. July 18 has been set as the date for shareholders to vote on the sale. Tesla Motors ( TSLA) is expanding its network of fast-charging stations nationwide. In a statement, Tesla said it is tripling the number of solar-powered supercharger stations in the country by the end of June so that Model S sedan drivers can travel from coast to coast. Using the supercharger network will recharge a vehicle to 50% of its battery capacity within 20 to 30 minutes. Tesla founder Elon Musk said the stations will always be free to charge the large-battery version of the Model S. Owners of the smaller-battery version will have to pay for the option to use the stations. According to Musk, the company's goal of 100 stations by 2015 is now on pace to happen twice as fast as the company originally planned. Twitter CEO Dick Costolo said the microblogging site has decided to "invest heavily" in TV. At the All Things Digital conference in Rancho Palos Verdes, Calif., Costolo said he sees television companies as valuable partners for Twitter, calling the social media platform "the social soundtrack for TV."