India is a strong, emerging solar PV market but it has a long way to go. With population exceeding 1.2 billion, India is in a rush to increase its power generation to meet its increasing demands with the ambitious Jawaharlal Nehru National Solar Mission (JNNSM) scheme. Solar installations in India recently grew to mo
re than 2.5GW, according to recent data released by the Ministry of New and Renewable Energy (MNRE). Although the growth has been impressive, there has been lot of concern about quality and maintenance.
Harsh conditions for solar installations
Despite its high degree of sunshine, India experiences ruthless weather conditions ranging from hot sunny days to monsoons and extreme winters. Solar panels have to hold up in all of these intensive environments, which can affect the overall maintenance and operations. Unfortunately the attention given to operations and maintenance (O&M) in India is negligible compared to other developed countries.
Other issues like theft and local vandalism are also problems in developing countries like India. So, more emphasis on security by fencing and night lighting is a musst. India also experiences conditions such as humidity and pests including rats, lizards, etc., that can also damage cables and inverters or other power electronic components.
The grid is not as stable as in many developed countries and this instability leads to frequent down time of solar plants. This instability leads to loss in revenue for the project developers. Grid feasibility analysis must be done carefully while choosing the site and also future developments should also be considered.
Rakesh Sigh, the co-founder and Director of Staten Solar said , “As far as failures are concerned the usual issues are found with the inverter due to insulated gate bipolar transistors (IGBT) failure or capacitor rupture. We also faced frequent down times due to cable damage by rat bites. Vandalism by the locals causes damage on solar panels and this affect the plant performance. Due to high moisture and humidity the MC4 connectors on the panel junction box have higher chance of rusting and can be a very big issue in the long run”.
Most of the MW-scale solar plants are sited in remote dessert regions due to low land cost, which leads to high soiling losses and hence regular panel cleaning is required. This further creates more loss when central inverters are used owing to less number of individual MPPT tracking is done. Therefore inappropriate cleaning of panels or damage or bird droppings or partial shading can guide to generation losses. So, appropriate emphasis should be given on panel maintenance and this should be taken care more where central inverters are used, says Giridaran Srinivasan, Senior Engineer from Zigor Corporación S.A.
He added that maintenance of off-grid/hybrid installation in remote regions can be very difficult during monsoon season and there are chances of battery draining below the Depth of Discharge (DOD) percentage. Also battery maintenance should be done regularly for lead acid-based conventional systems, which is done by noting the density of electrolyte and also making sure that regular top up of distilled water is added. It is also recommended to keep the terminals and metal connections coated with something like petroleum jelly.
General O&M services
The broad services include maintenance of the PV array, finding faults, ordering replacements, periodic cleaning of arrays, infrared checking for hot spots, checking for junction box or combiner box overheating, remote monitoring of power generated and matching with past performance to uncover abnormalities, seasonal power output monitoring versus predicted power, etc. And as said earlier the customization may include services like technical plant upgrades with time, depending upon the developer’s needs.
Preventive maintenance should be carried out by the EPC, which can be performed by effective fault finding. This requires continuously analyzing and comparing the plant generation with past performance to uncover any ab-normalities, after which they can take corrective action. The monitoring system can help the customer locate the bad performance by any particular string and also help to identify any issues with the inverters. Hence choosing a good monitoring system is a must to do preventive maintenance and fault finding.
Likewise attending the service calls by technical experts can be an issue in case of remote installations and these have to be calculated in advance by the EPC or the suppliers. Sometimes relocation of talented technical manpower is required, which can be a real issue because most of the site is located in remote regions. And it is a challenging task to get the experts out to such remote locations to work.
Little or no O&M of solar plants directly affect the power generation and in turn affects the capital invested. Levelised cost of energy (LCOE) is directly dependent on the performance, system costs and the on-going O&M of the solar plant in the long run. While system cost is an upfront investment, the O&M costs are a recurring expense that repays itself quickly by maintaining the plant performance and efficiency and in turn, safeguards the return on Investment by assuring the calculated generation figures/ revenue generation to attain the desired LCOE. Therefore preventive, corrective and condition- based monitoring for the solar power plant should be carried out.