As architects all over the world continue to focus on the potential for sustainable design solutions, there is one question that VELUX gets asked often: Is it possible to fit skylights with solar cells?
Skylights already represent an eco-friendly way to light up buildings and with solar cells on top, you have pretty much achieved green roofing.
This is the reason why Velux Modular Skylight has developed a solar cell solution for our customers. Or two solar cell solutions. We’ll get back to that.
In this article, we take an in depth look at how VELUX Modular Skylights integrate with solar cells.
What are the different styles of solar cells that VELUX Modular Skylights can be fitted with?
VELUX Modular Skylights offer two different solutions for architects that want to match solar cells with their skylights:
With the semitransparent option half of each skylight module is transparent like any regular skylight module and the other half is covered with solar cells in the shape of black squares. The solar cells are 15 x 15 cm and are evenly distributed over the skylight area.
The other option is a skylight module that is fully covered with solar cells without any transparency. This is known as the opaque module.
Now, you might be wondering why an architect would choose a modular skylight system without any transparency. Very few would. The opaque solution usually requires a formation of modules where some skylights are opaque and other skylights are entirely transparent.
Most often with some variation of transparent skylight modules facing the north, and the opaque skylight modules turned south to maximize solar radiation.
Which sizes and types of VELUX Modular Skylights are available with integrated solar cells?
VELUX Modular Skylights integrated with solar cells are available in all standard module widths from 800 mm up to 1000 mm and standard module heights from 1200 mm. to 2400 mm.
Both fixed and ventilated modules can be integrated with solar cells.
How do the solar cells function?
The skylight modules with integrated solar cells are nearly always connected in series (known as strings) in order to build up voltage.
The strings are connected to an inverter that converts current from the solar cells into alternate current that functions like regular electricity from the grid. This is how skylight modules fitted with solar cells generate free electricity to the building and its users.
The “water hose-challenge” One aspect of solar cell technology that is essential to understand is the so-called “water hose-challenge”. The serial connection of the skylight modules need each module to produce identical amounts of electricity.
If one module produces less electricity than the surrounding modules, it could weaken the whole module string. Similar to a water hose that when squeezed in just one place limits the water transport in its whole length. One module, that is suddenly in the shadows or otherwise dysfunctional, could weaken an entire string’s production of electricity.
In order to prevent one “shadowed” module to weaken a string entirely, VELUX Modular Skylights equip each module with 1 by-pass-diode. The diode allows the electricity flow to by-pass the inefficient module. This means that a weak module would not contribute to electricity production, but also not limit it either.
Are skylight modules integrated with solar cells as durable as standard modules?
Monocrystalline solar cells are not only very efficient, they are also extremely durable. One of the first solar cell technologies developed, there are monocrystalline solar panels that were build more than 25 years ago and still produce electricity to this day.