Process for technical site assessment

Site-specific criteria and trade-offs
The site-specific criteria are similar to the criteria covered in the privious blog roof requirement for a Solar system. At this stage, a key question might be how to mount the solar PV system on the roof and if a system should perhaps be elevated.
Depending on the location, the solar PV system could be installed with various tilts, or even almost flat within the tropics. Also to be considered is that a minimum tilt of 10° is favourable for self-cleaning of solar PV modules by rainfall.

Note that wind load affects elevated systems more than systems that are mounted parallel to the roof, as resistance to wind forces is less while uplift forces are greater when modules are free-standing.
Any kind of near shading should be avoided. To assess the suitability of a roof or a location on the premises, the sun path and resulting shadows at the longest and shortest days in the year have to be taken into consideration.

Technical design aspects for rooftop applications

Roof-mounted solar PV systems add weight load to roofs. Additionally, wind and potential snow loads need to be considered to confirm the structural integrity of the solar PV system and the building. Although most mounting structure manufacturers provide type-approved mounting structures, they do not take into account the building structure itself.
The weight of a standard solar PV module ranges from 15 to 20 kilograms per m², and it might be possible to install one or two modules even on top of a small building structure as long as it is reasonably stable. In other cases, the system designer has to consider the local conditions, including potential loading reserves. If it is not possible to install solar PV modules on a roof, a ground-mounted installation might still be possible or the better option.
However, for an SHS of around 3 kWp nominal capacity, solar PV modules would have a weight of more than 250 kilograms, so roof reinforcement might be necessary. In any case, experts should check the building in advance.