mdsolar writes "An Arizona utility commissioner is asking for all the key players in a debate over a solar energy policy in the state to reveal any additional secret funding of nonprofits or public relations campaigns. The probe comes after Arizona Public Service, the state's largest utility, admitted last week that it had been secretly contributing to outside nonprofits running negative ads against solar power. As The Huffington Post reported Friday, APS recently admitted that it had lied for months about paying the 60 Plus Association, a national conservative organization backed by the Koch brothers, to run ads against current solar net-metering policy. APS is currently pushing the Arizona Corporation Commission to roll back the policy, which allows homeowners and businesses with rooftop solar energy systems to make money by selling excess energy back to the grid. Solar proponents say that the policy has facilitated a solar boom in the state, and that changing it could have a huge negative impact on future growth."