United Solar Ovonic LLC has introduced PowerShingle, an integrated PV system into asphalt shingle roofing. It is expected to be commercially available in mid 2011. The product contains 193 mm wide strips of conventional roofing material with laminated 143 mm wide thin-film solar cells attached. The shingle is nailed to the roof like conventional shingles. An adhesive layer along the bottom of each strip attaches to the layer underneath. United Solar claims a 6.1% efficiency for the overall system, with cell efficiency at 8%. Connections are made with proprietary connectors located underneath the shingles. 600W units can be connected together into a string and the cable can be threaded through the roof. The shingle modules are expected to sell for $6.50 to $7.00.