Germany’s Solar Output Eclipses Demand For The First Time

Solar subsidies are a huge discussion in Germany recently. The Feed-In-Tariff which made it economical for large swaths of the building-owning population to invest into Photovoltaics has led to a land rush into installing solar capacities. It turns out that the growth in production is far outpacing even the most optimistic predictions. Just how far have we come in terms of solar power?

Reuters had a story yesterday about how Germany’s Solar output was up to 22 GW, from 14 GW just a year ago. That would be a difference of 8 MW capacity. For reference, the biggest German nuclear power plant has peak output of 1.4 GW. ¹ This would be a staggering growth in solar capacity within just one year, even surpassing the record growth of 2010.

However, Reuters mentioned that this provided just about half of the German energy demand. Which would’ve been surprising because usually, the aggregate for Germany during lunch-time isn’t anywhere near the Winter peak-demand of about 50 MW. So, being the energy geek that I am, I decided to check on the data. And what I found was pretty surprising.

According to the reported data, solar production outstripped demand for the first time in Germany.

This graph shows the aggregate System Vertical Load as reported by the Transmission Systems Operators², which is a good gauge for aggregate demand, and the Solar and Wind production as reported by the EEX. On Saturday, 26. May, we can see that the curve for Solar output cuts the curve for vertical grid load. At the peak, we have solar output of 22.1 GW with a grid load of 20.9 GW, a surplus of 1.2 GW – approximately one nuclear power plant.

We know of this phenomenon from Spain and Portugal, where it is a somewhat regular occurrence for peak wind output to eclipse off-peak grid demand, but for Germany, this is a new situation. And it is somewhat surprising that it happens this fast.

This puts new pressure on the legislative approach to reduce the Feed-in-Tariffs paid to Solar Photovoltaics, and necessitates renewed urgency in Smart Grid approaches to balance the energy grids.

Update: It turns out Vertical Grid Load is not as good a measure for electricity demand as I initially thought, as it systematically underreports demand, especially under conditions of high production in the low- and mid-voltage distribution networks, which is the case in scenarios of high solar production. I am looking for better data sets and will amend this post accordingly once better data is found.