For nearly 50 years, biophysicist and inventor Mária Telkes applied her prodigious intellect to harnessing the sun's power. She designed and built the first successfully solar-powered house in 1949 but was perplexed by the knotty scientific challenge of developing a reliable and economical way to store captured solar energy. Telkes held more than 20 patents at the time of her death in 1995.