Good information from Bob Wallace
High quality source and fairly current....
This one is interesting because it shows the wholesale price of electricity falling below the production price of coal and nuclear. By August 2015 the price was down to 30 EU/MHw (top graph).
And this graph give some insight into why. The top set of lines is from a day before there was much solar installed in German and the bottom set on a sunny day after a moderate amount was installed. The effect of just a little solar is to knock out all the more expensive providers during the sunny hours and lower the wholesale price of electricity to that of late night (low demand) hours.
Hope this is what you're looking for. If not, let me know and I'll see what else I have squirreled away.