Velux America. Now available for use in electric or gas water heating markets, the maker says its smaller one-collector solar water heating systems paired with a 60-gallon tank are ideal for projects remodelers may encounter. The smaller combination is designed to meet hot water requirements of most one- to two-person households. The systems are eligible for 30% federal tax credits through 2016 and are suitable for use anywhere in the country. 800.888.3589.