Solar and Energy Technology

Highest corrosion protection for the photovoltaic industry

Strip galvanised steel offers durability and best corrosion protection

The requirements for mounting systems in photovoltaic systems are extraordinarily diverse: In addition to the different types of systems such as open space or roof, the statics and the structural design, as well as in particular the durability, play a decisive role in the planning of a base frame. The basic material steel manages this balancing act, especially if it is provided with a long-lasting and maintenance-free protection against corrosion and mechanical stress. With its surface-treated steel strip, Wuppermann offers high-quality and resistant products for solar park operators. Wuppermann Austria in Judenburg currently produces piling sections, support tubes and C-rails for the PV industry. Wuppermann uses high zinc coatings (Z) as well as alloys of zinc, magnesium and aluminium (ZM).

 

Wuppermann produces strip steel with runs of 1200 g/m² in pure zinc and 1000 g/m² in zinc-magnesium

The standard for corrosion protection (DIN 55634-1) takes into account runs up to 600 g/m² for pure zinc (Z) and 430 g/m² for zinc-magnesium (ZM). But with these values, the production possibilities are by no means exhausted. In the strip galvanising plant of Wuppermann in Judenburg, Styria, runs of up to 1200 g/m² in pure zinc and 1000 g/m² in zinc-magnesium (Wuppermann Zink-Magnesium, short: Wzm) are produced - optionally with powder coating. This makes Wuppermann the only company in Europe that can produce such high Z and ZM runs. The high Z and ZM coatings open up undreamt-of possibilities for the harshest environmental conditions or piling profiles.
Even relatively new designs such as floating solar plants or agro-photovoltaic systems, where solar plants are installed on agricultural land, have particularly high requirements for corrosion resistance. In the case of floating, the steel is exposed to an increased salt and/or moisture content in the ambient air, and in the case of agro-photovoltaics, the fertiliser places particular demands on the steel. In addition, areas that have been contaminated by different previous uses are increasingly being used to produce renewable energy and are being upgraded accordingly. Steel coated with high zinc or zinc-magnesium coatings, such as Wuppermann Zink-Magnesium, is predestined for these applications.


Short delivery times and flexibility for rapid realisation of PV projects

Solar fields are project businesses with complex approval procedures. As soon as all approvals are available, rapid implementation is required. This means: fast deliveries, absolute adherence to schedules and flexibility. During the short construction phase, the material must be delivered "just-in-time", in the right quantity and in the right order according to the progress of the construction work. In addition, the pile-driving posts are the first components of an assembly system to be installed in a solar park. These logistical peculiarities can be mastered by close cooperation between a very experienced team at Wuppermann and the customer. This enables exceptionally short delivery times of 14 days to be achieved. The customer also gains even more time thanks to the already hot-dip galvanised steel: Wuppermann delivers a finished product - no on-site reworking is necessary.


The popularity of zinc-magnesium is growing steadily

In addition to the classic pure zinc coating, an alloy of zinc, magnesium and aluminium (ZM) is increasingly used. Different proportions of magnesium (Mg) and aluminium (Al) have different effects on the properties of the alloy and ultimately determine the area of application. For the partly very heterogeneous requirement conditions in the PV industry, an alloy composition with a slightly higher proportion of Mg and Al (about 3% each) than the most corrosion-resistant one has been found. Standardised laboratory tests and knowledge gained from practical experience in the meantime certify that this ZM alloy has about twice the corrosion resistance of pure zinc.


Advantages of continuous strip galvanising for the PV industry

As early as 1989, Wuppermann developed a then new technology for galvanising hot-rolled strip steel, thus laying the foundation for today's continuous strip galvanising process. In addition to the continuous process, there is also piecewise galvanising, in which the already finished components are dipped into a zinc bath. In the strip galvanising process, the steel is drawn as a strip continuously, i.e. continuously, through the pre-treatment and the zinc bath. The desired zinc layer thickness is then precisely adjusted by means of a stripper nozzle before the steel strip travels over a cooling section to cool down to ambient temperature. This results in two major advantages, especially for the PV industry, with regard to the zinc layer and the associated corrosion protection.

Firstly, the thickness of the zinc coating can be adjusted more precisely according to the application - only as much zinc as necessary to achieve the required corrosion protection is applied. Secondly, the very quick application of the zinc results in a more homogeneous and cleaner zinc layer. One argument put forward against continuously galvanised steel is that cuts or punchings made in the subsequent production process are uncoated and thus exposed to the weather without protection. This statement can be refuted by a very positive property of zinc. Zinc "sacrifices" itself as a less noble metal and protects the steel against red rust formation during natural weathering by means of an electrochemical process. This is called active corrosion protection or cathodic protection. Nevertheless, especially in the case of pile-driving profiles, the recommendation of longitudinally galvanised edges is advisable, as there is a particularly high risk of the formation of corrosion products in uncoated areas, especially in the soil-air transition. Wuppermann Austria in Judenburg offers correspondingly galvanised longitudinal edges up to a maximum width of 410 mm.

 

Reference products from Wuppermann:

  • Slit strip up to Z1200 (pure zinc)
  • Slit strip ZM1000 (zinc-magnesium)
  • Profiles with Z1200
  • Profiles with ZM1000
  • Holding frame for cells
  • Substructures
  • Anchorages
  • Connecting and fastening elements