I like data. So occasionally, I look at electricitymap.org. And to my surprise, it was 189.25 EUR/MWh! That's quite a lot, the highest I have ever seen. Usually it is not above 60-70 EUR/MWh during peak hours.
Highest prices were 189.25 EUR/MWh for Germany, France, Belgium, the Netherlands, Austria, and Denmark. Italy at 163.06 EUR/MWh, Great Britain 170.62 GBP/MWh, Spain 56.83 EUR/MWh, Poland (largely driven by coal) 84.74 EUR/MWh. At 05:00 the next day, the price for NL was at 39.80 EUR/MWh, and the peak morning was at 86.53 EUR/MWh.
What explains this? Well, I do not know. It was during peak hours on a week day, which is when there is the most demand. And, there was barely any wind through western Europe.(Unfortunately I do not have a screenshot of it, and a historic wind map is tough to find, the wind speed in Germany should give you an idea) And it is September, the sun is lower and setting earlier so less power on the early evenings. But I do not know if there was any reason for extra demand. Factories are open again, lockdowns are largely over, which is also a reason of course. Also, contrary to what I expected, EU ETS prices were among the highest in 10 years, near 30 EUR.s Though I still don't know exactly the price was so high.
You know, back in April, when I observed negative prices I didn't thought this would happen. Peak hours back then were also cheaper.
For future reference, German electricity prizes that week.
Update 2020-09-22: Yesterday at 19:00 CEST, a similar situation occured. For DE, NL, BE, LU, FR, DK, AT the electricity price was 200.04 EUR/MWh.