A life of any system is as good as the life of an individual component. You would normally hear from any system integrator system would last for more than 25 years. In India, the first solar industry started only a decade ago as such we haven’t seen a solar plant complete 25 years. However, there are still power plants in Countries like Japan that are running even after 30 years, which gives us hope that the systems could last longer. With time, Operation and Maintenance become more important so that system performs to its full capacity and lasts for longer time. Let’s look at maintenance involved with various components of a solar plant.
Life of a Solar Power Plant:
The main component of the solar plant is a Solar module. As solar modules are exposed directly to the sun, there are a lot of chances that dust in the environment could block the sun light hitting the solar cells. Any blockage of sun light due to dust, or foliage or bird droppings would not only reduce the solar generation from the solar module under shade but would also limit the generation from the clear solar modules that are connected in the same string as the modules under blockage. A string in a solar power plant is the series of solar modules connected in series. Usually, you have 16-20 modules in series. See Example below on how a soiling effect on a certain panel would affect the generation. In the above test set up, Panel A and Panel B are generating solar independent of each other. In case if both the panels were part of a single string, then even Panel B would have generated 57W like Panel A. It’s therefore important to clean up the modules occasionally. The frequency of cleaning of modules depends on the level of soiling that happens at the site. It could be weekly once to monthly once, depending on the geographic location of the site. Proper care should be taken to ensure that there are no scratches on the panel glass caused due to excessive use of abrasive cleaning materials like metal. It’s important the panels are cared like your glass windows of your home or like your car windshields. Since the solar modules are exposed directly to the sun, there are a lot of chances that dust in the environment can block the sun light reaching the solar cells.
A solar panel might last for 25 years, but the mounting structure that is holding the solar panels might weaken over years and can fall apart making the entire solar plant vulnerable. So it’s important that the components that we use for the mounting structure are durable and rust resistant. At Ecosoch Solar, we use Aluminum Structure which is practically rust resistant and can last much longer than the Solar Panels. Other than the rust formation, it’s possible that the structural stability of the plant has been maintained even during or after the windy storms. It’s important any reinforcements are done if the structures are found to become unstable over time. In case if the mounting structure is Mild Steel, there are more than certain chances that it will get rusted over time of 5 years depending on the salinity in the air. One way to avoid any rusting is to paint the structure with epoxy primers on the bare metal followed up by a paint of your choice.
In normal household applications, it’s common to see MS bolts and nuts. However, mild steel rusts over time especially if it’s exposed to weather elements. MS bolts and nuts to be avoided at all cost. Most solar installers use Galvanized nuts and bolts. There are relatively corrosive free. However, galvanized steel has zinc layer on the surface level, which when there is scratch, it tends to corrode.
The best is to use Stainless steel. Stainless steel is different from other steels as it doesn’t corrode or rust due to the higher percentage of chromium present in it. SS bolts and nuts are much costlier than the GI and MS fasteners. As said before, the other set of fasteners that are available in the market is Aluminum. Due to its relative strength, usually, only the Rivets are made using Aluminium. At Ecosoch Solar, all our fasteners that are used to fix the structure is made out of SS or Aluminum. This will ensure that the mounting structures last longer.
Unlike the solar modules that come with 25 years of warranty, the next expensive and important component of a solar plant is the inverter. Typically, these inverters come with 5 to 20 years of warranty depending on the manufacturer. However, they need to be frequently checked to ensure that they are not being turned off for errors like ground fault, overvoltage or under voltage even under normal conditions.
Unlike the regular AC cables found in the house hold applications, Solar cables used in the power plant systems are mostly used for outdoor use. These cables should withstand the weather elements like high temperatures and high UV radiation. It’s important that the DC string cables used are class II double insulated to protect against any short circuits and ground faults. It’s important that these cables are not exposed to direct weather elements and are routed inside UPVC weather resistant pipes. Unlike the pipes used for AC wiring inside a building, these pipes are available in only few stores and need to be special ordered.
All the electrical components come with ratings and have a limited lifespan. Any failure of an electrical component or any loose cable that is not properly fastened might eventually lead to higher short circuit currents or voltages which could potentially damage any electronic components like inverters or even solar panels. It is important that these components are checked periodically, at least once every six months to ensure that there are no hot and loose wires dangling inside the junction boxes.
Electrical components – Fuses/Circuit Breakers/SPDs:
A junction box or distribution box is where the breakers are installed. A junction box must be IP 65 compliant so that it is protected from any water ingress from any direction.
Apart from that, there are many other items like glands, clamps, screws that are used in balance of systems need to be frequently checked.
Last but not the least is the ability to remotely monitor the health of the rooftop PV system. There are various types of monitoring systems that could be used to monitor remotely. The type of monitoring depends on the type of inverter. A monitoring system helps in pre-emptively find out the fault and rectify the system. A typical monitoring device gives the information like Power, Energy generated today, Life energy, Life savings in Rupees, voltages, and frequencies in each phase. All this information could be used for preventive maintenance of a solar plant and reduce the downtimes drastically.