Balcony solar panels can save 30% on a typical household’s electricity bill and, with vertical surface area in cities larger than roof space, the appeal is clear
To be a positive impact, they just need to be less carbon intensive thans the energy they displace. According to the first results on google, (presumably utility-scale) solar is about 12 times less carbon intensive than natural gas and 20 times compared to coal. So as long as you’re replacing base load and not utility solar, balcony solar could be as much as 10 times less efficient and still come out a net positive.
Keep in mind also that these numbers keep improving as solar panel manufacturing becomes more efficient and starts using more green energy itself over the coming decades
To be a positive impact, they just need to be less carbon intensive thans the energy they displace. According to the first results on google, (presumably utility-scale) solar is about 12 times less carbon intensive than natural gas and 20 times compared to coal. So as long as you’re replacing base load and not utility solar, balcony solar could be as much as 10 times less efficient and still come out a net positive.
Keep in mind also that these numbers keep improving as solar panel manufacturing becomes more efficient and starts using more green energy itself over the coming decades