In view of the steady decrease in solar module prices, in Europe, with its high proportion of diffuse radiation, the use of solar tracking systems generally does not pay, particularly in view of the higher investment and upkeep expenses entailed by these devices. That said, the use of solar tracking systems could be justified on the grounds that such systems allow for a higher number of full-power hours. The most prevalent mounting modalities for solar generators (which are normally mounted in a fixed position) are specially designed mounting racks in open spaces and mounting on building facades or pitched/flat roofs. In some cases solar generators are installed on existing terrain elements such as highway or railway sound barriers.
Framed modules are as a rule more mechanically robust than laminates. A metal frame also provides good edge protection and is beneficial for lightning protection as well. Framed modules are particularly suitable for installation in open spaces and for systems that are made for and installed on existing buildings. Framed modules are often secured to mounting racks using bolts and to a lesser extent module clips. Myriad mounting systems are available that allow solar modules to be attached with relatively little effort. However, framed modules have drawbacks relative to laminates in that grit tends to accumulate at their lower edges and snow takes a relatively long time to slide off them.
Moreover, laminates are more aesthetically appealing for building integration purposes. Most laminates weigh about the same as framed modules owing to the thicker (6-10 mm) glass that is needed for the requisite sturdiness. Laminates are often integrated into fagades or roofs in the manner of plate glass, although it needs to be borne in mind that laminates are exposed to more extreme temperature fluctuations than is the case with standard building glazing. Laminates can also be installed using special module clips (with inserts made of elasticized plastic such as neoprene) or can be glued in place using
Figure 4.44 Ground-based installation comprising Siemens M55 laminates (53 Wp) for the Mont Soleil system (560 kWp) at 1270 m above sea level. The tilt angle is b = 50° so as to allow snow to slide off (the space below the installation allowing). The laminates were glued onto the galvanized steel mounting rack using a special silicone adhesive (Photo: Siemens)
silicone adhesive. However, owing to the absence of a frame, laminates must be handled with extreme care in order to avoid breakage.
For mounting solar modules on pitched roofs, various manufacturers sell special solar roof tiles that are used in lieu of standard roofing tiles. However, if the weight per surface unit of these solar roof tiles is less than that of standard roofing tiles, additional fastening elements must be used to prevent the solar tiles from being blown off by the wind.