BJ's Wholesale, Estee Lauder, Kohls, Target, Tiffany & Co., Wal-Mart. From "big box" discount giants to high-end jewelry retailers, solar energy has become big business in 2007. The most recent retail-outfitter to become part of this trend is Macy's, which announced earlier this month it will install solar power systems on 26 stores throughout California.

Along with the PV systems, PowerLight is assisting Macy's with energy efficiency upgrades at the 26 stores, including high-efficiency lighting and HVAC systems and energy management systems. According to the company, combining solar power with efficiency will allow Macy's to achieve an estimated 40% reduction in utility-provided energy, almost doubling the impact of the solar power alone.