Light colors, such as white or ivory, are rarely recommended for most solar collector absorbers. However recently-developed solar technology using perforated glazing on wall-mounted solar air heaters made solar possible without bearing dark paint costs or altering the 26,000-square-foot building's exterior aesthetics. The solar air heater appears more like a wall of windows than a solar collector for Plastech (Sherbrooke, QB) a division of the MI Integration Group that supplies injection molded interior and sealing parts to the automotive industry.
Plastech's Lubi wall-mounted solar air heater manufactured by Enerconcept Technologies (Magog, QB) is the world's most efficient solar collector rated at an 80.7 efficiency by the Canadian Standards Association (CSA-International). On a black surface, the Lubi is 20% more efficient than any other wall-mounted solar glazing or metal collectors. On a white wall such as Plastech however, the Lubi is 58% more efficient than any other competitors.
With darker colors, the collector can provide air temperatures of up to 45°C above ambient outdoor temperatures and maximum outputs of 800-watts/m2. Since its installation at Plastech in late 2010, a 25°C temperature was recorded on sunny days, a performance which was previously unheard of in the solar industry for a white collector.
Using dark walls as an absorber is recommended for optimum solar performance efficiency, however the inherent performance disadvantages of Plastech's light colored wall were offset with a 40% larger collector. After incentives from Natural Resources Canada and a rebate from the Energy Efficiency Fund (EEF) of natural gas utility, Gaz Metro, the payback on the project is four years. Besides C$6,000 in annual savings, the collector reduces Plastech's CO2 emissions by 15 tons/yr.
Installed by Sherbrooke-based metal contractor, RTSI, the 90 x 24-foot-high wall-mounted solar collector has clear glazing that from a distance appears like windows. Sunlight radiates through the glazing where it is absorbed by the building's corrugated steel wall. The Lubi's efficiency is attributed to its patented design featuring 906 perforations per 3 x 1-foot-long panel. As the indoor ventilation fan draws collected warm air through the six-inch-deep collector, ambient air draws through the perforations and cools the panels. Unlike other wall-mounted solar collectors that suffer significant heat loss through the glazing or metal facade, the panel's airflow cooling minimizes heat loss and increases efficiency.
The addition of wall-mounted solar heating offers multiple advantages to Plastech. Throughout its minimum 15-year lifecycle, it will reap at least $90,000 (based on 2011 energy prices) in projected annual energy savings and eliminate more than 300-tons of CO2 emissions from the environment, while it simultaneously providing employees with better indoor air comfort. -[email protected]om