Media reports on renewables like to focus on record highs in output (if you wish to promote renewables) or record lows in production (if you want to denigrate renewables). In the long run, averages are probably what really matter. The medium term problems (until storage can be figured) are most commonly thought of as being caused by very low wind output. However the last two days of wind power output in Germany offer a nice snapshot of how highs in output are probably a greater medium term limitation.
So, pretty stable at around 22 GW all day yesterday. But a large drop from 22 GW to 5 GW in about 12 hours today. How does this output compare to demand? Total power supply is shown below (green stuff is wind, yellow solar, and gray is everything else.)
So, the percentage of Germany’s electricity coming from wind peaked at about 43%. Not bad, however let’s try projecting wind power into the future. Currently Germany is getting 8% of its power from wind. Let’s say we wanted to push that up to 20%. In this future scenario German wind production at 2 am this morning would have been almost 10% higher than total demand. So, a way of storing this power is going to be needed to get past 20% without significant problem, be it batteries or building a large number of inter-connectors to Norway to use their hydro plants as batteries. Germany could, for a while, just export the power. However their eastern neighbours are currently not so enthralled at the prospect.