A solar array gathers sunlight for electricity. But something has to convert that energy from direct current to alternating current before it can be fed into an electric power grid. Toledo-based Nextronex Power Systems says it has come up with a simpler and more efficient way of doing that. While competition is stiff, Nextronex claims an advantage over suppliers that provide only inverters -- the box that converts DC to AC. The company provides a complete system that it says can be easily installed. The Nextronex system also uses multiple inverters that switch on and off as energy from the sun ebbs and flows during the day, resulting in less loss of power than typical one-box systems. Founded in 2008, the company had 10 employees in 2010 but expected to increase that number substantially within a year.