KRANNICH SOLAR BLOG

global solar distribution
Flat roof systems from K2-Systems

Flat roof systems from K2-Systems

When should I use which flat-roof elevation and why?

S-Dome System

S-Dome System (10°, mostly south elevation)

Solution for:

  • Maximum power yield per module, i.e. over the module lifetime, a south elevation (in the northern hemisphere) at midday produces the highest yield.
  • Power grid feed-in, i.e. if the electricity is fed into the public power grid during the day or can be temporarily stored without direct own use.
  • Large roofs, i.e. if there is enough space on the roof for a width-dependent row spacing to avoid shading.

Where:

  • Generally: Useful on any latitude if maximum module yield per module is the main criterion.
  • Special: The closer the system is to the equator, the closer the module rows can be, i.e. the less shadowing caused by the previous module rows.

Advantage:

Individual system design possible, as the components can be mounted on the rail at a flexible distance from each other.

D-Dome System

D-Dome System (10°, mostly east-west elevation)

Solution for:

  • Optimum utilization of roof area, i.e. more modules can be installed on the roof since no shading distances between the rows have to be considered.
  • Use of electricity for own consumption, e.g. in the manufacturing industry. The system produces an even yield from sunrise to sunset, which can be used directly without an additional storage tank.


Where:

  • In general: Useful at any latitude, with direct power consumption.
  • Special: In northern latitudes (Central and Northern Europe and corresponding latitudes around the globe) more yield per roof area is possible compared to the southern elevation.


Advantage:

Lower costs for assembly and substructure per module compared to a single-sided module support.

 

 

S-Rock System

S-Rock System (15°, mostly south elevation)

Solution for:

  • Maximum power yield per module, i.e. over the module lifetime, a south elevation (in the northern hemisphere) at midday produces the highest yield.
  • Power grid feed-in, i.e. if the electricity is fed into the public power grid during the day or can be temporarily stored without direct own use.
  • If slightly lower shading losses or a larger distance than necessary can be accepted, since the prefabricated components correspond to two standard dimensions (S-Rock and S-Rock Short).

 

Where:

  • Generally: Useful on any latitude if maximum module yield per module is the main criterion.
  • Special: There are two length variants of S-Rock: S-Rock and S-Rock Short. The original S-Rock component has been dimensioned for a row spacing of 1.76 m (module width up to 1000 mm) and keeps systems at latitudes from ≤ 48.8°N to the winter solstice (21 December 12:00 noon) "shadow-free". The S-Rock Short has a row spacing of approx. 1.5 m and can be used for lower latitudes, ideal for ≤ 41°N.


Advantage:

  • Completely assembled component, railless
  • Cost advantage through handy and quick installation on the roof
  • Direct ballast absorption in the component
  • 5° higher elevation for slightly higher module yield with correspondingly adapted row spacing

 

Mounting systems with south elevation: S-Dome and S-Rock

Mounting system with east-west elevation: D-Dome

Why do the systems have "only" 10° and not 30°?

Mounting systemAbout the advantages compared to a standard triangular mounting system
In our latitudes (Central and Northern Europe), the optimum angle of inclination for PV modules is between 25 and 55 degrees, depending on location and season. When elevated (90° azimuth) in accordance with the opposite angle to the angle of solar radiation (azimuth), a PV module then produces the maximum yield.
Nevertheless, it often makes more economic sense not to place the modules in a system at the optimum angle to the sun, even if this results in a lower yield with the individual module.

  • The steeper a flat roof system is installed, the more it has to be ballasted or fixed against wind (i.e. lifted off). Most roofs have only a limited load capacity, which may be applied in weight or a roof substructure, to which may not be fastened. The S- and D-Dome as well as S-Rock system are therefore ballast optimized.
  • Due to the smaller installation angle of 10° or 15°, the module rows can be assembled more closely. This means more modules can be brought onto the roof and thus more yield from the roof.
  • A smaller angle of elevation also means less material to be used. This in turn reduces weight, resources and costs.
09.04.2018 14:57
by Sina Glaser

Go back