We need to know more. Is this supposedly the power supply to the whole site or the power available for a circuit in a block of share parking garages? Is it common property power or the supply to individual units we are talking about?
Each individual unit has its own garage, with at least 2 10 amp power points.There is not enough space in the common property to install a a shared EV charger. The power supply is such that 100 amps is shared by 3 units, so 300 amps for all 9 units (if that makes sense, I don’t really understand electricity!). The residents interested in EVs have roof top solar panels and smart meters. The complex is 25 years old and was set up for a mix of electricity and gas. It might be worthwhile having the wiring checked for the whole complex as people discard gas appliances in favour of electric ones.
Thanks for the extra info. 100A shared by 3 units is a bit tight. You certainly don’t want three units charging at 32A each leaving nothing over. However, what you can do is allow the existing 10A power points in the garages to be used. Most cars are supplied with portable charge cords that tell the car to draw up to 10A. Some are conservatively set to only 8A. Either way, you are likely to be fine at 10A if you make a rule that charging is not permitted for 4 hours during the evening, say 5PM to 9PM. This is the time of peak demand when people are turning on heaters or air conditioners, cooking, TVs, etc.
Units with solar will be aiming to charge during the day with solar. Most car models can be set to schedule when they charge and when they pause charging. So, you could have the car set so you can plug in any time you like but the car will only charge during solar hours or it will pause its charging during the evening peak period.
Nine cars each charging at 10A each overnight from a 3x100A supply is only 90A out of 300A. That is no problem outside of the peak demand period.