Despite Phoney Tony’s Tea Party denials, ad infinitum, it’s actually mortgage belt and elderly folks who have been installing more and more rooftop PV. It’s these and wind farms which keep power prices low on dreaded, very occasional peak power days. At such times, big coal and gas power stations, as they tender for supply in peak time slots, can bid as $12.90 per kWH compared with usual wholesale of $0.50/Kwh. In just a couple of days, they can make 25% of annual profit. But more renewable energy means demand can be met with less fossil fuel power, which means they need to bid less to win a share of supply business.