You can use hot water and/or solar electric panels on this project. A hybrid system that uses both would be best in my opinion because, the byproduct of electric generation is heat and hot panels operate less efficiently. By combining solar hot water with solar electric you can jump the efficiency of the entire system from 15% typically to as high as 60% and have all the hot water you need for free and more efficient electric production. Sun Drum is a product that attaches to any conventional solar panel system to make it a hybrid system. We've designed this in several locations. You can also install the system and run the whole building through 1 meter or split it up by apartment. If you split it up I'd suggest using microinverters which monitor and control power panel by panel rather than as a single array, which is more typical. We've used microinverters with a lot of success. Owners like them because if there's a problem with one panel or one inverter, the whole system does not go down. I'd also suggest you consider installing a battery backup system tied in to the panels, otherwise the grid is your battery and if it goes down so do your panels as systems are conventionally designed.