Our complex of 141 apartments is about to add solar to the roof which is flat. The return on investment is estimated at around 12% which is way better than what we get for the funds we have invested. We won’t need batteries as we will use all the power generated. Having conducted a full review of all power useage in our building we identified a number of inefficient practices and reduced power costs by about 30-40% with more to come so it’s worth doing if you haven’t already. If the solar installation is successful we will consider looking at more difficult parts of the building for solar installation eg outside walls with the only fly in the ointment being the issue of potential future shadowing from neighbouring developments ( a seperate but important topic in this era of rising power prices)