Solar PV System - Key Asset Management Considerations

March 10, 2020   Energy

Solar PV system – Key Asset management considerations

Last decade has seen a consistent growth in new capacity addition in Solar PV systems in almost every part of the world. This growth has been achieved through new installations of both small and large size solar PV systems by retail and corporate segments.

However the growth in new capacity addition has not resulted in proportionate growth in energy availability from installed capacity due to number of factors of which one of the most important is the deficiency in the operations and management of the installed solar plants.

A Solar PV system, which apparently has no moving parts  seems like a silent machine which might require only little attention but in reality, a solar PV systems employs dangerous levels of DC current and voltages and has its own design and Engineering complexities thus require prudent care and attention by all solar PV assets owners and manpower working on them to ensure optimum energy generation, overall plant reliability, safety, and long life.

In order to achieve the maximum possible usable life and optimized plant efficiency in terms of generation output and plant availability, carefully planned operations and maintenance procedures can be a source of extended life and faster payback. We will deliberate on various factors that play a crucial role in determining the performance of a solar PV system, along with an evaluation of prudent O& M approaches to achieve optimum performance in terms of energy generation and ROI.

 A) Design Stage Considerations

Factoring O&M requirements before construction

When the design and the engineering team is working on the initial project concept due to consideration should also, be given to various requirements by the operations and maintenance team .Wherever required ,sufficient tolerances should be made in the design to  facilitate operation and maintenance of the Solar PV system. Due consideration to operation and maintenance requirements before construction will also minimize unforeseen costs arising out of unplanned modifications post-commissioning.eg. provisions must be made for walkways and safety lines so that modules and workmen safety can be facilitated for Rooftop installations.

Due consideration to standards and benchmarks

Plant performance and safety of operations are interlinked. A good performance can only be achieved if proper consideration has been given to safety and security of the assets , manpower power and environment.  It is imperative that design and Engineering be entrusted with the agencies that have proper qualification and adequate experience of working with standardized practices and procedures for Solar PV system design and construction in accordance with standardized norms and specifications.

Lifelong costs of operations and maintenance to be factored

Investment decision for solar PV system return on investment is generally made on the basis of upfront capital investment without serious consideration on future recurring O&M costs. There can be a sizeable cost in the form of component replacement, repairs, obsolescence, breakdowns and unpredictable failures. Additionally, there can be unforeseen influences due to changes in business scenario, manpower cost, and nonavailability of human resources in later years of plant life. We should factor in such cost while evaluating a project from returns perspective and only invest if ROI is good even with all costs factored in.

 B)During Projects Execution, Considerations

Supervision by the owner during construction

It is advisable that owner of the Solar PV system engages his manpower for general supervision when the plant is still being constructed , this will facilitate his team to understand and learn the typical demands and challenges which might arise in future due to the complex working of components in the plant itself. This proactive approach should be preferred because during construction face it is easier to grasp the complexities of.

Preparation, handover and maintenance of Technical records

The solar PV system is warranted to work for around 25 years; it is important that it’s all necessary records are maintained and handed over to the Asset owner once the plant has been commissioned. If in the later years there is any component breakdown then warranties can only be availed when there is proper documentation available and records can be verified for the proper execution of the project. After receiving the records from the execution team onus is on the owner to maintain these records on a regular basis so that faults diagnosed in future can be traced back and proper corrective actions can be taken with the help of good documentation.

Clarity over the scope for parties

A solar system requires coordinated efforts by different parties for supplies, execution, and post-commissioning performance. It is highly desirable that there are clearly defined responsibilities for parties participating in the execution, operation, and maintenance of the Solar PV system. This will help to avoid any misunderstanding related to handling the responsibilities during various phases of project life cycle.

C) Post Commissioning Considerations

Post commissioning technical due diligence

Once the plant construction has been completed it is prudent on the part of the owner to ensure that plant has been commissioned in line with the contracted requirements by the EPC contractor. In general asset owners are not qualified to evaluate a commissioned plant regarding these requirements. A competent technical Agency may be employed who can inspect and certify that EPC activities have been completed by the contractor in line with the contractual agreements and in case there is any deviation they have to be corrected or the owner has to be compensated in line with the scale of such deviation.

Ensuring safety management post-commissioning

The EPC contractor is required to fulfill all the regulatory requirements related to safety procedures and compliances during construction phase but once construction has been completed it becomes the responsibility of the Asset owner to comply with any safety norms and provide for any resources which are required to comply with regulatory requirements for safety of the operations, assets and men power. So it is advisable that owner deputes a qualified person to evaluate the work till commissioning and decide what kind of safety requirements have to be met by the owner and necessary arrangements should be done  plant has been handed over to the owner and plant operations and manpower safety becomes the responsibility of the Asset owner.

Independent evaluation of O and M activities

Generally O&M  activities are contracted out to third party companies which only visit the Solar PV system for scheduled maintenance purpose as per their contracted schedule. In most such cases, the Solar PV system owner is not technically qualified or competent to evaluate the work done by a third party agency. In a worst-case scenario, even the third party agency which is doing O&M might be employing unskilled manpower to cut costs. It is suggested that an independent, qualified expert is brought in to supervise and evaluate the quality of work done by the third party agency so that there are enough checks in the system to identify a big potential breakdown.

D) Technical Considerations

Shading of solar panels

Although due care is taken during design and Engineering stages to ensure that there is no shadow on solar modules,  in later years we have to pay the attention that any vegetation, tree, etc which may cause the shadow on solar panels has to be trimmed, removed to maintain optimum energy generation from a solar PV system. The manpower engaged in day-to-day supervision and maintenance has to be duly instructed and regularly followed up with for this purpose.

Soiling effect on solar PV systems

In most of the countries solar PV systems are preferred to be installed at the rooftop or  on a large tract of land which is located far away from populated areas. Ambient air almost always causes some soil and dust particles to be deposited on solar panels which is further aggravated by the stickiness caused by  humidity, dew and entrapped pollutants.

The soiling on the Solar PV module can drastically reduce the efficiency and energy generation from the Solar PV system. If a proper arrangement has not been done to clean the dust from the Solar modules generation of energy from a solar PV system can reduce even by 30% due to soiling impact.

As a good industry practice, it is recommended that solar modules must be cleaned at least twice in a month so that to keep performance degradation by soiling within bearable limits. If possible we should prefer modules that come with specially coated glass for lesser soiling. In certain places ambient air might contain contaminants and chemical pollutants like cement and limestone dust, acid fumes etc. In such cases, it is recommended that modules are cleaned with specialized cleaning agents made to take care of the effect of contamination by soiling.

Due to the critical importance of module cleaning, a dedicated module cleaning system has to be part of every solar PV system with provisions for supply and storage of clean water in adequate quantities along with properly designed pumping and piping arrangements to facilitate the cleaning of solar PV systems.

As module cleaning requires clean water in ample quantities, we should make provision for recycling and reuse of water once it has been used for module cleaning. A good alternative to water-based module cleaning can be robotic cleaning which employs dry cleaning with the help of cleaning brushes.

Overall any investment made in a good module cleaning system will result in higher energy generation and increase in useful plant life for the Solar PV systems.

Array performance imbalance

Different arrays in a big solar PV system will tend to perform at different performance levels and their operating current and voltages will differ from each other. The performance of the system will be impacted by the least generating array hence different arrays have to be regularly monitored and balanced to maintain optimum energy generation and module life. We can do this by carefully monitoring the data from different arrays in the Solar PV system.

Thermal imaging equipped with drones plays an important role in identifying faulty, underperforming arrays and specific modules.

Once an imbalance has been detected among the different arrays proper diagnosis should be done and underperforming array has to be given due treatment to achieve a balanced performance for the Solar PV system. For this, we should regularly analyze the data received by the monitoring system and we should highlight the errors and specific modules that are underperforming.

Once the underperforming array and specific module have been highlighted for under performance we can use a PV analyzer or IV curve tracing instrument to check the module behavior in comparison to theoretical performance. Depending upon the specific condition we may like to replace or repair the modules in question to achieve balance among the performance of different arrays in the Solar PV system for optimized energy generation and system.

Cabling and connectors

During regular operation cables are subject to Extreme voltages and current, humidity, stresses and unforeseen influences. This may cause damages to the conductor or sheath. Also  we should carefully pay attention to watch out for improper cable bending and cable routing which might be causing inappropriate twisting and strains in the cable thus might be a potential reason for damage to the cable or life of the workman maintaining the plant.

Damaged cable can be reason for both loss of energy and dangerous electrocution to the workmen. Cables can also be damaged due to biting by rodents and other creatures. Regular supervision by operations team can avoid a big unattended loss to the Solar PV system.

Inverters and accessories

Inverter is like the heart of a solar PV system. If the inverter is not functioning then simply there will be no energy generation from the installation. A well maintained, good performing inverter may be operating at around 98% efficiency level however if proper O&M is not being done  its efficiency can even drop to 70% which will bring down the efficiency of the complete solar PV system . For optimum performance, an inverter should be in a clean, well-ventilated environment protected from unnecessary exposure, flooding and unauthorized access.

Plant condition monitoring

Regularly collected, carefully evaluated and duly acted upon condition monitoring data will help us to plan maintenance activities so that Scheduled shutdown time can be minimized. Based upon the inferences derived from the condition monitoring data we can make provisions for stocking required standby components ,consumables and spares so that minimum time is lost due to troubleshooting.

For utility-scale solar PV systems it is always advisable to keep spare units of critical components like modules, connectors, inverters  etc. Required and Scheduled repair, maintenance activities must be sacrosanctly performed when they are due as per schedule and there should be no exceptions to this rule.

Safety procedures and vigilance

No unauthorized access is to be  allowed as it may cause a serious damage to the Solar PV system  or for the unauthorized person due to dangerous DC current and voltages in the system or unpredictable faults occurring due to unskilled person’s intervention. All cleaning, repairing, supervision must only be performed by well trained, qualified and designated persons only.