SolarCity has claimed the highest module efficiencies with 22.04% conversion efficiencies.

The company said that its 100MW pilot line in Silicon Valley would be producing the modules in “small quantities” in October, 2015. 

SolarCity noted that the module with the industry record conversion efficiencies was independently verified by the Renewable Energy Test Center, a third-party certification testing provider for photovoltaic and renewable energy products.

Source Solar PV tech: http://www.pv-tech.org/news/solarcity_producing_pv_module_with_industry_record_22.04_efficiency_from_pi