A system and method of drying wet items including roving packages, cakes and bobbins of wound wet glass fibers and/or wet glass fiber strand(s) by first preheating the wet items using waste hot gases coming from any source including a glass furnace, a dryer or a heat engine operating to generate electrical power prior to removing much, most or all of the moisture in the wet roving packages, cakes and bobbins using a dielectric or microwave oven, to save energy, reduce drying costs and to increase the capacity of dielectric or microwave dryers.