Mounting structures hold Solar Panel modules and arrays in the proper place. A mounting structure is supposed to bear various kinds of loads – wind, snow, mechanical pressure, thermal influence, as well as the load of the mounting structure itself.
Solar array mounting and related wiring should be reliable yet simple to enable Solar Panel easy module replacement, without the need of dismantling the whole system.
Racking components hold the Solar Panel array to the spot where the solar modules are placed.
There are various ways for Solar Panel array mounting.
The solar array can be mounted on a roof. Another option, which is becoming increasingly popular, is building-integrated mounting where a Solar Panel array can actually be a physical replacement of the roof covering (on modern office buildings). Very often a Solar Panel array can be mounted on the top of a pole rack – as is the case of solar lamps in parks.
The Solar Panel array mounting type is selected by carefully considering:
- Orientation towards the sun
- Site shading
- Weather at the location
- Roof material and bearing capacity (in case of roof mounting)
- Soil type and condition (in case of ground-mounting)
Don’t forget that:
- Not every mounting construction is suitable for any kind of module. Furthermore, certain kinds of modules are designed for a specific mounting type.
- To ensure sufficient cooling of the Solar Panel modules, which leads to higher system efficiency, enough room has to be provided beneath them.
- A design visa and a building permit are usually required.
- All the necessary applicable construction regulations must be complied with. The best plan is to ask the supplier of the Solar Panel modules to install them on the roof.
Mounting types: Pros and Cons
The main types of solar panel mounting are as follows:
- Sloped roof mounting
- Flat roof mounting
- Ground mounting
- Roof-integrated mounting
- Facade mounting
We’ll briefly review them by stressing on their benefits and drawbacks.
Sloped roof mounting
- A recommended mounting method
- Above and parallel to the roof slope
- Promotes array cooling by allowing air to circulate beneath the array, which:
- reduces heat gain into buildings by separation from the roof, and
- provides underside access on the rooftop for diagnostics and maintenance
- Can be used effectively for new construction on existing homes
- Cables should be selected according to the outdoor environment
- Supporting structure should be designed for at least 30 years of lifetime
- Preferred materials: aluminium, stainless steel, and glass fibre.
Benefits of sloped roof mounting:
- It is the easiest, the quickest and the most economical way of Solar Panel modules mounting. Often such constructions are installed without any external help
- Can be usually installed on existing roofs
- Easy to dismantle and not so easy to be stolen
- Solar panels are mounted in high, so shades from trees and neighbour buildings are avoided
- There is sufficient cooling in the rear part of every Solar Panel module
Drawbacks of sloped roof mounting:
- Often roof orientation and slope are not the best for achieving maximum performance of the Solar Panel array
- If the roof needs to be repaired during the next 15-20 years, the best moment to do that is before installing the Solar Panel array. This means that the system installation costs are going to increase.
Flat roof mounting
Benefits of flat roof mounting:
- Easy, quick and economical to install Solar Panel modules can be installed in an optimal orientation and tilt
- Easy to uninstall for repair and maintenance
- Sufficient air flux in the rear part of every module
Drawbacks of flat roof mounting:
- Not every module type is suitable for flat roof mounting. The wind effect on the construction should be carefully considered since Solar Panel arrays act like ship sails to the wind. Therefore, the constructions have to be balanced by concrete blocks or another type of counterweight, which appears as an additional load for the roof.
- Modules mounted on flat roofs are more vulnerable to shading than modules mounted on sloped roofs, especially in winter when the sun is low in the sky and shadows are longer.
- On high roofs, due to wind exposure, reinforcing the construction (e.g. by fixing the mounting construction of the strings at several points on the roof) might be needed which is an additional load for the roof. Furthermore, enough spacing should be provided between rows of solar modules in order to avoid inter-row shading.
- If during Solar Panel modules mounting, hydro insulation of the roof gets compromised, a piece of advice from roof repair experts might be needed.
Benefits of ground mounting:
- Easy, quick and economical to implement
- Solar Panel modules can be installed at optimal orientation and tilt
- Modules are easy to uninstall for repair and maintenance
- Sufficient air flux in the rear part of every module
- Solar Panel modules are even easier to install than on flat-roofs since no load-carrying capacity of the roof is to be estimated
Drawbacks of ground mounting:
- Occupies a part of an area that could possibly be used otherwise
- Vulnerable to shading (from the neighbouring modules and from the nearby buildings and trees)
- Vulnerable to soiling
- Solar Panel modules are easier to be stolen than when mounted on the roof
- Replaces conventional roofing materials thus enabling cost savings in new buildings
- Amorphous modules are suitable for roof integration
- There are special Solar Panel tiles – a specific design of Solar Panel modules designed for roof integration
Benefits of roof-integrated mounting:
- Such constructions are usually quite agreeable aesthetically
- They are mounted in high, thus shades from trees and neighbour buildings are avoided
- Solar modules are hard to be stolen
- The module wiring is not exposed to outdoor conditions
- Self-shading is avoided
Drawbacks of roof-integrated mounting:
- Labor intensive Limits planning any possible roof repair activities, at least in the near future
- Dimensional tolerances are important
- Relatively more difficult access to module wiring
- Increased operating temperature due to warming the surrounding air layer – therefore efficient venting elements should be provided
- Solar Panel modules can be used not only for producing electricity but also to present a certain corporate identity
- Facade mounting is usually related to the mounting methods of conventional façade construction elements
Benefits of facade mounting:
- Solar Panel modules mounted on the facades of prestigious buildings could be certain kind of alternative of expensive facings
- Usually, there is enough area available for modules mounting
Drawbacks of facade mounting:
- Low performance (sunlight is not falling at an optimal angle)
- Facade mounting is to be done by experts rather than by amateurs
- Not every module is suitable for facade mounting
- Careful research of regulatory documents related to facades might be required
Sources: German Energy Society. 2008. Planning and Installing Photovoltaic Systems – a Guide for Installer, Designers and Engineers. Antony, Falk, Christian Durschner, Karl-Heinz Remmers. 2007. Photovoltaics for Professionals: Solar Electric Systems Marketing, Design and Installation, Routledge.