Can the roof withstand the weight of a solar system?  
     
  Yes! The heaviest normal REG family solar heater weighs totally about 225kg fully filled with water. This weight is distributed in 4 squre meters on 6 legs. The load on each leg is far within the permitted weight on roof stipulated by NY Housing Code.
 
     
 
 
     
 
Figure 1. Load and Footprint Dimensions
 
     
 
 
     
 
Figure 2. A solar water heater installed on a slope roof.