Building with the Sun in Mind: Galvanized (Zn) Steel (Hot Dip, Pre Galvanized), Posmac (Al+Zn+Mg+Si) and Galvalume (Al+Zn+Si) for Solar Power Plants
The sun’s energy is a powerful resource, and solar power plants are increasingly harnessing it. But what holds up all those solar panels? Solar Structures of galvanized steel and Galvalume steel – durable, cost-effective, and weather-resistant metals that form the backbone of countless solar farms.
Galvanized (Zn) Steel (GI): A Time-Tested Champion
Galvanized steel is steel coated with a zinc layer through a hot-dip process. This zinc layer acts as a sacrificial barrier, protecting the underlying steel from corrosion. The general coating for Zn varies from 80GSM to 550GSM, with 80, 120, and 275GSM being the most common grades available in the market. Coatings and usage are as follows:
- 120gsm – Cost effective but life is not up to the mark. Most widely used in Rooftop Plants
- 275gsm – Good Rooftop EPC contractors use it. This is the bare minimum for a good life for a Solar Plant
- 350gsm and more – used in ground mount projects and highly corrosive environment
The zinc layer acts as a sacrificial layer on steel, thereby preventing the underlying steel from corrosion and granting it long life in outside weather. This long life is essential to sustain the 25yrs promise for solar plants.
Galvalume (Al+Zn+Si) Steel (GL): The Next Generation
Galvalume offers an upgrade on galvanized steel. It combines a zinc layer with an additional aluminum layer, creating a more superior corrosion barrier. The most common coatings for AZ are AZ70, AZ150, but many other variants also exist. Typically, an AZ70 performs better than 120 GSM GI Steel, and AZ150 performs better than 275 GSM GI Steel, for some comparison.
The aluminum layer provides additional protection, particularly in coastal environments or areas with high humidity, and in general would improve the longevity of your plant structure in an external environment. In addition, Galvalume’s lighter color reflects some sunlight, potentially reducing heat absorption in the structure. Al being a lighter element with the same micron coating weighs less creating a cost-benefit, which can be seen in big projects.
POSMAC (Al+Zn+Mg+Si): The Champion
Posmac, with addition of Magnesium (Mg) to its composition, provides a 5-10 times stronger corrosion resistance than the products above. The company even guarantees corrosion resistance for 20 years. This additional resistance is due to the formation of a dense and highly stable corrosion product called “simonkolleite” (Zn5(OH)8Cl2·H2O) when Mg comes in contact with environmental elements (Details).
While this is the most expensive product among the three, it can over the years be more cost effective in highly corrosive environments, through reduced maintenance cost and longer life. The usage of POSMAC, however, would be recommended only in specific areas where corrosion is a huge cause of concern, due to its cost.
Building a 1 MW Solar Power Plant: A Steel Skeleton
Let’s use a 1 MW solar plant as an example. Here’s how galvanized steel and Galvalume might be used:
- Ground Screws: These screw piles made from galvanized steel provide a secure foundation for the structure, especially on uneven terrain.
- Support Posts/Columns: Heavy-duty galvanized steel posts form the vertical supports for the racking system.
- Rails/Rafters, Bracing and Purlins: Galvanized steel rails or purlins are used to create a horizontal framework that holds the solar panels in place. Galvalume can be used here as well, depending on the specific environmental factors.
A typical plant would use ~ 40% Galvanised Steel and 60% Galvalume Steel for its structure, with a typical quantity requirement of ~20 tonnes of steel for 1 MW plant. Cost could vary between ₹90-100/kg as per current steel rates (subject to change).
India’s Solar Push
The Indian government has set ambitious targets for solar energy as part of its plan to make the country’s energy consumption more sustainable. Galvanized steel and Galvalume steel, known for their durability, affordability, and corrosion resistance, play a vital role in supporting India’s push for solar power.
Here are a few key points to consider:
- Government Initiatives: The government has introduced various initiatives and policies to promote solar energy adoption, such as the National Solar Mission and the rooftop solar scheme (PM Surya Ghar) with subsides and a promise of zero electricity bill for the masses. These initiatives have created a conducive environment for the growth of the solar industry in India.
- Make in India: The government’s focus on promoting domestic manufacturing aligns well with the use of galvanized steel and Galvalume steel. These materials are manufactured in India, contributing to the growth of the local steel industry and creating employment opportunities. They are also cost effective solutions for large scale projects and are hence a viable option for our ambitious targets.
As India strives to become a global leader in sustainable energy, these versatile metals will continue to be instrumental in harnessing the power of the sun. And they will also help you save costs on your electricity bills significantly with the solar plant paying back in 4-5 yrs on average (Solar calculator), and giving you returns for 25 years.
The Takeaway: How can our firm help achieve your Solar goal?
Galvanized steel and Galvalume are the go-to materials for building robust and reliable solar plant structures. Their strength, affordability, and corrosion resistance make them ideal for supporting the sun’s energy revolution. As solar technology continues to develop, these versatile metals will likely remain a key component in harnessing the power of the sun.
We at BLD Steels Private Limited are here to help you build great “Make in India” structures for your Solar Plants. We help make structures from leading steel companies in India like JSW, Tata Steel, AMNS and have our deliveries from Delhi, Navi Mumbai, Gujarat , Ghaziabad and Haryana. We generally have material ready in all grades of galvanized and galvalume steel, and can customize the structure based on your requirement. Please reach out to us, share your BOQ (Bill of Quantities) with us, and help us get you solar ready.