3 ms·

Because the roof structure already exists.

• dashundchen 8y ago
  Expanding on that, built up areas are where the demand and grid already exists, but not necessarily the clear space. Little added transmission capacity is needed. In a neighborhood in my city where a few large electric users have expanded, the utility has been subsidizing rooftop panels for residential users to minimize summer peaks and avoid having to upgrade the old undersized grid. So far it has worked pretty well - peaks usually line up with the hottest sunniest days.