Chinese regulatory agency General Administration of Quality Supervision, Inspection and Quarantine has found that about 23% of solar modules produced by Chinese companies for the domestic market fail to meet quality requirements, reports Bloomberg. The module defects found by the regulator are in the panels’ antireflective coating. The regulator did not identify specific manufacturers, but it did note that solar glass coming from the eastern province of Jiangsu was particularly flawed, with 40% of products from that region showing defects. Defective solar modules installed at solar parks typically will not show signs of reduced power output for several years. Thus, since most of China’s solar capacity has been installed since 2012, Chinese solar developers have yet to see the impact the flawed modules will have on their investments. The defective glass was found in tests conducted in the third quarter of 2014 with samples from 30 companies. These producers represent about half of China’s suppliers of antireflective glass. In a another recent quality test, the China General Certification Center found that 425 utility-scale solar parks built in China between 2012 and 2014 had flaws of some sort. These flaws include faulty solar modules, poor construction, design flaws and project mismanagement and will likely lead to lower power output than originally expected. The China General Certification Center conducted tests on 3.3 GW of installed PV project, or about 10% of China’s installed solar capacity at the end of 2014.