Yes, there was a decline in electricity prices, for the world as a whole. The cost was to Germany. Like I told you above, don't ignore that.

Are we talking about a specific policy or the whole transition?

The Wikipedia page on the EEG suggests that it's globally recognised as a success, and even when political pressure was being applied to reduce solar PV feed in tariffs faster than the original plan called for due to better than expected uptake, the merit order effect introduced in the same legislation was reducing the spot price of electricity by more than the cost.

https://en.wikipedia.org/wiki/German_Renewable_Energy_Source...