Plug Power shares are tumbling on Wednesday after the fuel-cell maker reported first-quarter net losses wider than analysts expected. Over the three months to March, Plug lost 6 cents a share, a penny wider than analysts forecast. Meanwhile, revenue of $5.6 million slipped 13% but beat expectations. The drop in sales was primarily a result of a fall in orders. Plug shipped 165 GenDrive fuel cell units, a more than 30% drop in orders from a year earlier. However, the company expects business to pick up as the year progresses. In its second quarter, more than 650 units are expected to be shipped.