Solar Panel Roof Shingles
The National Research Council (NRC) of Canada released, in their December 2011 Construction Innovation newsletter, that they are evaluating the possibilities of using building-integrative photovoltaic (BIPV) shingles and turning the low sloped roofs, typically found on commercial supermarkets, industrial warehouses and school buildings, into energy producers. BIPV shingle products are expected to become available in Canadian markets sometime in 2012, if they already aren’t available.
A study published in November by the National Renewable Energy Laboratory (NREL), compared BIPV systems with traditional roof mounted photovoltaic (PV) systems. The study found on average BIPV systems had a reduced efficiency of around 6-14% conversation rate, compared to 15% conversion rate for roof mounted PV systems. The primary reason for reduced efficiency in BIPV vs. roof mounted PV systems was the lack of air flow beneath the solar cells, increasing the cells operating temperature, resulting in increased corrosion of the metalized key components.Overall the study looked at the unsubsidized levelized costs of energy (LCOE) between these systems. The levelized cost of energy is the installation costs, plus the lifetime maintenance/repair costs, all over the expected lifetime electricity production amount. The study looked at two locations: Tucson and Boston, the levelized cost per kWh was $0.19 and $0.25 respectively. Assuming Boston most likely represents an average Canadian environment, when compared against the peak electricity rate in Toronto, ~$0.15 (all costs in) per kWh, a BIPV system ends up being just less than twice as expensive as simply grabbing energy from the grid.
In this event a BIPV system might be beneficial if electricity prices increased by 70%, or if the costs of installing and maintaining a system was halved, or its operational lifetime doubled. The latter would be less desirable in regards to the time value of money, but could be considered as a hedge investment against a possible increase in electricity costs.
Overall a BIPV system does save common building material costs, such as asphalt for roof shingles or mounting hardware for roof mounted PV systems. However because BIPV are being directly installed on the building material, the products must adhere to higher quality standards and building codes. When compared against traditional mounted PV systems, in addition to improved quality over typical roofing systems, BIPV shingles could offer an aesthetic value to home or commercial building owners, interested in the look, or values that BIPV can represent.