Installing solar plant near coastal area is always a concern for the solar installer. Choosing right kind of material which resists all kinds of corrosion is the key for the successful running of solar plant for a longer periods.
Corrosion is nothing but the degradation of metal parts due to chemical or electro-chemical reaction. It is a natural process which affects the various components of solar plant over a period. The most familiar form of corrosion is rust which results from the oxidation of metal.
Corrosion affects the solar panel frame, mounting structure, electrical wires and contacts in the solar panel and its junction box.
Types of corrosion in solar plant
- Salt Mist corrosion
- Galvanic corrosion
- Amonia corrosion
Salt Mist corrosion
It is predominant in coastal area where salty air breeze contiously flowing and there are most likely chance of salt mist deposition over metal parts and junction boxes. The chemical reaction accelerates with temperature. The solar panels are made from Aluminium alloys. Oxidation of aluminium forms a protective layer which stops further degradation.
Warmth and humidity increase the rate at which corrosion occurs. Salt corrodes when its wet and high temperature accelerates chemical reaction. In places where the weather and waves tend to be wilder then 200 meters is the danger zone. We need to ensure that we use solar panels that are corrosion resistant.
Galvanic corrosion
It is electro-chemical corrosion. It occurs when two different metal comes in contact with each other. Salt water forms an electrolyte and two different metals form an anode and a cathode. More vulnerable of the two metals will start corroding. For example when aluminium frame of solar panel comes in contact with steel iron structure, galvanic corrosion starts.
Ammonia corrosion
Ammonia corrosion occurs when solar plant is nearer to animal farm where lots of animal excretia is present. This is least affecting solar plant.
How to protect various components of solar plant from corrosion?
Solar Panels
Choose wisely those solar panels which are in confirmity of IEC61701 standard. If you are going to install solar panels in danger zone, then select Level 6 resistant solar panel.
There are six levels of corrosion resistance to the IEC 61701 standard. Level 1 is suitable for marine environments such as on roofs by the beach. Levels 2 to 6 represent increasing levels of corrosion resistance. To receive a level 6 rating panels have to survive 112 days of testing that simulates decades of exposure to a salty environment with less than 2% decline in power output. While they’re not quite suitable for use on submarines they should be able to handle any exposure that doesn’t require being submerged in salt water. Technically level one resistance should be all that’s required for solar by the coast, but fortunately most panels that are certified have better than level one resistance, with level 6 resistance being very common, so you are unlikely to have to settle for the lowest level of protection.
Most solar panels meet the above criteria and they proudly declare in their datasheet confirming IEC 61701.
Solar Inverter
Solar inverters can also corrode. High quality inverters are normally quite resistant with IP65 protection mandatory for them. In an area with heavy sea breeze, it is recommend that either it should be installed inside a room or providing some form of shelter such as cabinet.
Cheaper inverters will be more likely to suffer from corrosion. But it is probably still be a good idea to either install them inside or give them some kind of protection.
Mounting structure
Best way to protect your mounting structure from corrosion is to use hot dip GI material. Generally 80 micron thickness of galvanizing coating is all required to increase its life.
If required painting with silver oxide at interval of 10 years can suffice.
Galvanic corrosion can be minimized by using hot dip galvanizing iron structure in combination of with stainless steel nut bolt.
Junction Boxes
All junction boxes should be IP65 protected. It should be installed in a enclosed space where water dripping or sea breeze can least affect. Regular checking of cable terminals to clean of any oxidation will be a good practice.
Moral of the story
To sum up if there is any chance that solar panels will suffer from sea salt corrosion, then get panels that meet the IEC 61701 standard for salt mist resistance because if you are installing quality panels anyway it is likely to cost you very little or nothing.
If you are in a location that does get a lot of salt spray, consider installing your inverter in a cool garage or providing it with some form of protection. Also consider adding an extra panel to your roof to make up for power lost due to salty grime on your panels.
Use of hot dip GI structure with painting at regular intervals will be a good practice.
All junction boxes must be IP65 protected and should be installed indoor.
If you follow above instruction, you will be at peace of mind.
