Wallingford-based Distributed Energy Systems Corp. has closed on a $12.5 million loan a Washington D.C.-based private equity fund. The fund, Perseus, gets a 12.5 percent interest rate on the loan, and five-year warrants to purchase nearly 8 million shares of Distributed Energy’s stock at 80 cents a share, slightly above where it’s currently trading. Bud Cherry, the newly elected chairman of Distributed Energy, called the deal a “critical step in the rebuilding” of the company. The deal contemplates a second, $15 million loan, although that must first be approved by the company’s stockholders.