Apollo is a low-profile photovoltaic array that can be installed along with the shingles by a certified roofing contractor. It can also be set up on existing roofs. According to the manufacturer, the high-efficiency polycrystalline cells can produce 12 watts per square foot. The array is designed to be incorporated into asphalt shingle roofs with a minimum 4/12 pitch. Contractor’s costs range from $0.75 to $1.50 per watt. CertainTeed, 800/233-8990, certainteed.com
