When everybody cranks up their usage when prices fall and stop when prices rise then the whole system might be unstable wildly swinging between low and high usage. Added with natural changes from solar and wind it's a tough nut to crack.
>>_nalpl+(OP)
In particular I suspect that even the most reactive energy sources (which I suspect are fossil fuels) takes minutes to scale up or down to follow demand.
>>afiori+H23
This is not a problem, because in my market each day at 17:00 the fixed hourly prices for the next 00:00-24:00 period are published. Weather and therefore renewable energy yield is good predictable for 24 hours.