What is plug-in solar?

Earlier this year I wrote about alternatives to rooftop solar, and all the many ways you can benefit from solar power without investing in a full scale installation. The most intriguing of those alternatives is balcony solar, which has been booming in Germany over the last couple of years. Known as balkonkraftwerk, there are now millions of balcony solar installations across the country.

Solar balconies have now spread to Spain, the Netherlands and France. Belgium recently legalised them and ...