Solar power may be cheaper than electricity generated by fossil fuels and nuclear reactors in three to five years because of innovations, said Mark M. Little, global research director for General Electric Co. If we can get solar at 15 cents a kilowatt-hour or lower, which I'm hopeful that we will do, you're going to have a lot of people that are going to want to have solar at home,'' Little said. The 2009 average US retail rate per kilowatt-hour for electricity ranged from 6.1 cents in Wyoming to 18.1 cents in Connecticut, according to federal data. GE said in April that it had boosted the efficiency of thin-film solar panels to a record 12.8 percent. Improving efficiency, or the amount of sunlight converted to electricity, helps reduce costs. The panels will be made at a plant GE intends to open in 2013. Most solar panels use silicon-based photovoltaic cells. The thin-film versions, made of glass or other material coated with cadmium telluride or copper indium gallium selenide alloys, account for about 15 percent of the $28 billion in worldwide solar-panel sales. First Solar Inc. is the world's largest producer of thin-film panels, with $2.6 billion in yearly revenue.