Mounting system types

Module frame with mounting holes. Left: A rail and clamp system. Right: A PV module with the proper mounting holes marked.

PV modules should be attached to some kind of structure to for pragmatic reasons like preventing damage from wind and loss to due to theft, but also to ensure that the tilt and orientation is correct to maximize energy production. A typical PV module comes with an aluminum frame for the purpose of protecting the rest of the module and to provide a means for it to be secured. A PV module be secured and supported properly. Module anufacturers provide holes in the frame for mounting with bolts, that serve to identify where it is appropriate to anchor the module. There are two primary ways in which a PV module is mounted onto a structure:

1. Through the bolts that are in the back of the module frame.
2. Using clamps that secure the module to a rail.

In either case the module should be supported and secured in the areas where the bolt holes are in the frame otherwise it may be damaged due to weather. It is important that the module is properly tightened down regardless of the system that is used to secure it, but not to the point that it distorts the frame at all. The manufacturer will have specifications for how tight is appropriate on the specifications sheet for a module, but an installer in many parts of the world will simply have to rely upon their judgement.

Either mounting style (using the holes or clamps) can be used with a variety of different mounting systems that have different advantages and disadvantages that typically make one type the most appropriate for a given application.

Roof mount

A roof mounted PV system using rails and clamps.

Mounting PV modules on the roof of a home is the most typical approach around the world. The PV modules sit on rails that are anchored into A system of this type the structure that underlies the roof (perlins, timbers, etc). Clamps are used to hold the modules to rails.

Advantages

• Low cost as the roof structure already exists.
• No custom fabrication required.
• Limited amount of material required. Easy to transport to the jobsite.
• Simple installation. No concrete.
• Does not occupy space around the home that could be used for another purpose.
• Out of the reach of children, domesticated animals and theives.

Disadvantages

• Existing roof structure may not be appropriate to work on or support a PV system. It needs to be evaluated.
• The tilt and orientation of the roof is typically used and is often not optimal. This can reduce system performance.
• Roof surfaces can generate significant amounts of heat that can reduce PV module production.