WAUKESHA, Wis.--(BUSINESS WIRE)--Generac Holdings Inc. (NYSE: GNRC) (the “Company”), a leading designer and manufacturer of power generation equipment and other engine powered products, today reported financial results for its first quarter ended March 31, 2015. First Quarter 2015 Highlights Net sales were $311.8 million during the first quarter of 2015 as compared to $342.0 million in the prior-year first quarter. Residential product sales were $156.8 million during the first quarter as compar