This is not so much a policy applied from the top, but requested from the bottom. People want to contribute to the transition, and balcony solar installs are a cheap and simple way to do this.
I do see it as the result of policy applied from the top, the policy that resulted in 2x household electricity prices compared to the US (which amounts to 3x difference if you adjust for median household income).
I replied in another thread but I still remember how in my childhood all the ordinary people had to grow potatoes. The state didn't order them to, it just created food shortages that's all. You can say it was voluntary, "not so much a policy applied from the top".
This is assuming people don’t want to go net zero, and people not understanding that going there requires change, which will be costly. I‘d argue there is a majority in Germany supporting the transition to green energy, accepting higher prices as a result.
I don't think that this is comparable. People who struggle with their electricity bills can not afford balcony solar. It has a ROI of a few years with a (low) but comparably large one time upfront cost.
This is not so much a policy applied from the top, but requested from the bottom. People want to contribute to the transition, and balcony solar installs are a cheap and simple way to do this.