Solar is the fastest growing renewable energy in the world. With the increase in its affordability and the per unit cost coming at par with other conventional sources of energy, the government is giving thrust on addition of renewable energy capacity. Most of the investment in the solar plant goes into the steel structure that supports the energy generating solar panels for three decades. The role of mounting structures is two fold, one is to optimize the costs involved and make a solar power plant economically viable and the other is to ensure the durability of a solar power plant. Solar Plants which are more than 5 years old, have started facing the issue of corossion.
The life of a solar PV system may be seriously effected by corrosion. Even the galvanised structure gets corroded after some time. Corossion can happen due to:
- Insufficient deposit of zinc in Galvanisation Process
- Mechanical damages during transportation and erection
- Atmospheric conditions
- Lack of periodic maintenance, etc.
This can cause serious structural failures in racking and mounting components. This can hamper the design life of the solar panel, since if the underlying structure supporting the panel gets corroded, it shall in turn affect the solar panel. The best method of protection of the underlying structure is application of Proper Coating System.
We, at Mohan Paints, have developed a specialised coating system for solar panel module structure, which saves the underlying structure from corrosion. The specialised coating system has been tested at Acme’s solar plant in Khambat, Gujarat. We are delighted to share that the painting system has shown excellent results and has stayed intact for more than five years. It has saved the corroded galvanised structure from further corrosion.
To overcome the corrosion at Solar plant, we recommend manual cleaning of the surface and application of our customized painting system specially designed keeping in mind the existing site conditions. Since the painting has to be done at the erected site, blast cleaning is not practically possible. Following method of surface preparation and painting system needs to be followed:
Surface Preparation
The performance life/durability of painting primarily depends upon good surface preparation. The following methods need to be adopted for surface preparation:
- Clean the surface with chipping hammer to take out heavy corrosion rust/scale.
- After the initial hand tool cleaning, use Hand Grinder with Metal Wire Brush as the accessory and clean the affected area to a standard of SSPC SP 3. In other words, when this Power Tool is applied over the affected area, the surface should become free of any visible rust/ contaminants and become smooth and shining and devoid of any coating whatsoever.
- Replace the Metal Wire Brush with the Sand paper and roughen the surface so that it creates a surface profile of around 15-20 microns (signifying that the surface metal has become rough with angular peaks and troughs) to enable it for accepting the first coat of Surface Tolerant Primer. Just after this cleaning, use sturdy cloth / jute soaked in Washing Solvent for wiping the surface clean.
Painting System
Once the Surface Preparation has been done, the following Painting System needs to be followed:
- Apply MOHPOXY Surface Tolerant Rust Converter Primer (DFT- 15-20 microns per coat). Care has to be taken that this primer is applied within 60 minutes of sanding.
- After overnight drying of Surface Tolerant Primer, apply a coat of MOHPOXY HB Red Oxide Zinc Phosphate Tolerant Primer (DFT- 40-50 microns per coat). Allow this to dry overnight.
- Apply Two Coats of MOHTHANE Hi Build UV-Stabilised PU Coating (DFT- 35-40 microns per coat). The two coats have to be applied after a gap of one day.
Paint Application
- The paint shall be applied brush or by spray or combination. The paint should penetrate into all crevices and corners.
- Sufficient number of drop cloth should be provided and care shall be exercised to protect all finished surfaces and other work and all the spots and marks from such surface shall be immediately removed. Care should also be taken to avoid falling of paint on the moving element of equipment. Use tarpaulins to avoid falling of paint on finished products or running equipment.
- During the preparation of paint / primer mixing with catalyst or thinner, time lag between inter coat, maturation time, pot life etc. should be maintained strictly as recommended.
- Prior to removal of paint material from container, stir the content thoroughly. Care should be taken to properly stir the contents of the drums after opening for at least 20 minutes before using them. Improper mixing may not give adequate corrosion protection. This is essential for overcoming settlement effect and maintaining uniformity of product.
- Do not plunge the painting brush too deep in painting material, this results in overloading brush bristles and in filling “heels” with paint. Remaining excessive paint also give lesser covering of paint.
- Hold brush normally at 45 degree to the work; make several light strokes of brush with paint. Ensure uniform spreading / wetting of the surface, in one direction and cross wise lapping strokes be continued.
- Do not pull dry brush on wet paint. This will break the wet film, reduce hiding capacity and DFT will be poor. This is uneconomical way of paint saving.
- When the surface is completely covered, again take little paint and brush the surface with light strokes to smooth up the brush marks when the surface is just covered with paint.
- Surface so painted has to perform with result of uniform gloss, uniform hiding of under surface, uniform dry film thickness, no porosity, no breaking of film and no over stretching / flexibility failure on drying.
- The paint shall be applied in accordance with recommended standard and should have good workmanship.
- The thickness of each coat of paint shall be regularly checked by means of a “Dry Film Thickness Gauge” or similar instrument. The paint coat build up shall be checked in dry condition.
Protective measures to be taken:
- Protective eye gear and gloves should be worn at all times before commencing any cleaning/ painting operation.
- Paints should be stored under shade and within temperatures of 20-35 degrees celsius.
- Paint shall not be applied under the following circumstances:
o Relative humidity is above 80%
o Ambient temp. is less than 15 degree C
o During rain, fog and mist
About Mohan Paints
Protective Coatings from Mohan Paints offers cost effective solutions to all corrosion problems, designed to protect assets against the specific corrosive environment they are exposed to. Our coatings are tested under extreme conditions to ensure that they are durable and can withstand the vagaries of the different climatic conditions. Today our coatings find use across diverse industries such as steel plants, solar plants, nuclear or thermal power plants, chemical, petrochemical or fertilizer plants, equipment manufacturers, sugar, pulp and paper industry, onshore/ offshore structures, etc.
