Last week ... the wholesale price of electricity in Queensland fell into negative territory - in the middle of the day. For several days the price, normally around $40-$50 a megawatt hour, hovered in and around zero. Prices were deflated throughout the week, largely because of the influence of one of the newest, biggest power stations in the state - rooftop solar. Negative pricing" moves, as they are known, are not uncommon. But they are only supposed to happen at night, when most of the population is mostly asleep, [and] demand is down That's not supposed to happen at lunchtime. Daytime prices are supposed to reflect higher demand, when people are awake, office buildings are in use, factories are in production. That's when fossil fuel generators would normally be making most of their money. The influx of rooftop solar has turned this model on its head. The impact has been so profound, and wholesale prices pushed down so low, that few coal generators in Australia made a profit last year. Hardly any are making a profit this year. State-owned generators like Stanwell are specifically blaming rooftop solar. The problem for Australian consumers [comes] in the cost of delivery of [electricity] through the transmission and distribution networks, and from retail costs and taxes. This is the cost which is driving households to take up rooftop solar, in such proportions that the level of rooftop solar is forecast ... to rise sixfold over the next decade. Households are tipped to spend up to $30bn on rooftop modules. It is not clear how centralised, fossil-fuel generation can adapt. In an energy democracy, even free coal has no value.