The key to the installation was that Perpetual Power was brought in during the design process and could work with the contractor to use its proprietary "Oasis" roof mounting system, which uses minimal connections and a low weight per square foot to reduce stress on the building's rooftop. The new mounting system also passed a rigorous wind tunnel test to meet area requirements, and ensure stability and safety.

"This time we were able to install [the panels] as it was being built," Townsend says. The installation did not extend the construction period for the building, which took four months to erect.

The result is that the array is providing a significant portion of the power for the facility. The facility is not off the power grid, but in fact will be selling some power back to the utility. In fact, climatecare.org estimated the array will produce 600,000kilowatt hours resulting in an annual savings of approximately $100,000. That result is far ahead of plan.

"Initially, we were shooting to offset 40% to 50% of the power," Townsend says. "We will actually [offset] 60% to 70%. We've saved them money from year one."

Based on this estimation, the amount of carbon saved by installing the system is equivalent to driving over 22 million miles over the 25-year life of the system, or keeping 8,000 tons of CO2 from entering the environment. "A cold storage facility is an excellent example of a building that can gain immediate benefits from solar power," says Gina Heng, general manager of Mitsubishi Electric's photovoltaic division, in an announcement. "Due to the high temperatures and amount of refrigeration required for this facility, solar panels can help the company shave off its most expensive tier it pays to the utility, resulting in immediate savings."

But there are reasons why the Markstein facility is unique--so far. A similar array may not work in all circumstances, Townsend observes. "Initially, it's a high capital cost," Townsend says.

In addition, many existing roofs cannot hold the weight of a large solar array, while others may be populated with HVAC units and other equipment. But that may change. "Newer technologies are getting more sophisticated," Townsend says. "It's all about the building and the roof."