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After completing all stages of design and construction (regulatory, land, engineering, acquisitions, installation and commissioning) of the photovoltaic plant – as well as, in some cases, the measurement cabin, substation and connection line – it is necessary to start the O&M (Operation and Maintenance) plan to ensure the correct functioning and durability of the equipment.
The actions and good practices involve controlling and managing the operation in real time, as well as monitoring the system's performance and carrying out any preventive and corrective maintenance to solve problems that may interfere with energy generation and result in loss of productivity, reduction in the expected functionality time of the plant's main products and systems.
Another point to be highlighted in these processes is the importance of reducing operational costs, eliminating the risk of injury to employees and mitigating the occurrence of generation interruptions.
In other words, the O&M segment is directly related to OPEX (Operational Expenditure), which is the cost of keeping the system in operation and in good condition, including expenses with materials, equipment, properties and real estate. In the context of the solar sector, it is the cost necessary to keep the plant in full operation.
We can therefore say that within the concept of O&M there are definitions of the following activities:
- Operation: monitoring the performance of the functioning and operability of equipment and systems;
- Maintenance: corrective and mainly preventive actions (actions taken 'on time' to avoid future problems and generation losses) of situations that interfere with electricity generation and UFV productivity.
Most common problems encountered in PV plants
Before we get into the processes and stages of operation and maintenance, it is important to highlight, firstly, the main problems encountered during the operation of a photovoltaic project.
O Strategic Study: Distributed Generation 2021 | Photovoltaic Market 2st Semester, developed by Greener, highlighted the biggest difficulties reported by consumers.
Among the most common are inverter malfunction and burnout; transformer burnout; problems with circuit breakers, cabling and connectors – as well as with the monitoring system; tiles breaking during installation; poorly positioned modules and their breakage.
When it comes to panels, for example, they can present several problems during their useful life. Most of them occur due to the use of low-quality materials and manufacturing processes.
The most common are: cell cracks and fissures; blistering; delamination; discoloration of the encapsulant; snail trail, cell misalignment; solder and metallization failures; hot spot, junction box and MC4 connector failures; and the PID-induced degradation effect (potential induced degradation).
O&M activities: preventive maintenance
To prevent these cases mentioned above and others from arising, preventive maintenance work is necessary, which, as the name suggests, is the prevention of problems and system malfunctions.
“A 12 to 32-month contract is drawn up, offering a schedule of services and measurements to be taken, which ensure more effective operational predictability,” said Kleber Alota, a PMP (Project Management Professional) certified professional and technical director at AK Energia Solar.
According to him, the main activities of the team that performs these functions include:
- Cleaning of photovoltaic modules;
- Vegetation control (brush cutting);
- Wildlife control;
- Drainage and flood control (unclogging/unblocking ditches);
- Cleaning, conservation, painting, lubrication, fixing, tightening of mechanical components;
- Alarm response and repair of non-essential components in energy generation;
- Reparameterization of equipment to improve availability and efficiency;
- Maintenance on MV circuits and cubicles located in the electrical center.
- Retightening screws;
- Thermographic analysis of modules, inverters and main connection points (hot spots).
We can therefore say that preventive maintenance consists of inspecting, performing tests and periodic measurements on strings, inverters, fixing structures and electrical connections. Some equipment such as a thermographic camera and IV curve tracer can help”, highlighted Elvis Almeida, Director of New Business at MySol.
Geraldo Dias, operations director at GLD Energia, shares the same idea and added that, with regard to hiring an O&M company to carry out preventive work, regardless of the scope contracted and the size of the system, it is recommended that a detailed mapping of the property and plant boundaries be carried out regarding the following items:
Organization
- Conservation status and points of attention of the perimeter fence;
- Internal or external drainage that may affect generation;
- Type of soil to define the tools that will be used for maintenance;
- Access and availability of drinking water for washing modules;
- Assessment of vehicle traffic or the existence of plantations around the property to estimate the need for washing modules or, in large projects, map which areas require more washing than others in the park.
Generation
According to Dias, it is suggested that, with regard to contracting maintenance of generation items, the company carries out a new commissioning, even if the plant has only recently started generating, to attest and understand the system in detail regarding:
- Measurements obtained;
- Torque of screws of energized connections;
- Condition of the module support tables;
- Status of modules.
“With this data, the plant report is issued upon receipt and from this date onwards, generation monitoring begins, always using the project data for reference,” he reported.
Corrective maintenance
If, even after the work carried out above, low plant performance is identified, it is recommended to call specialized technical assistance to restore the initial and ideal operating conditions of machines and equipment, eliminating any sources of failure that may exist.
In other words, adhere to corrective maintenance, which acts in a specific and targeted way to solve one or more problems that are preventing the operation of the photovoltaic plant.
“When a product or system stops operating or stops working properly, there is a need for immediate action to replace the damaged component and get the plant back up and running,” explained Alota, who also listed the main points identified by the O&M team at this stage:
- Detection (and correction) of faults and alarms;
- Mitigation of problems that caused failures and alarms and composition of plant control reports;
- Replacement of damaged parts and pieces;
- Repair of modules, inverters, combiner boxes, skids, transformers, electrical centers;
- Appropriation of causes of out-of-warranty failures;
- Reporting production failures to the end customer;
- Analysis of product or component degradation, implementing repairs or awaiting orders for recovery;
- Readjustment of warranty terms, when necessary;
- Repairs to external lighting circuits;
- Repairs to monitoring systems, CCTV (Closed Circuit TV) and fiber optics at UFVs.
Operations
When it comes to the operation of the photovoltaic plant, it is based on the activities carried out by maintenance, stated the technical director at AK Energia Solar.
“This is because, as a system is a significant investment, it is crucial that it can function well for a long time. This longevity is possible – the plant is designed to operate for many years – but it requires constant inspections to maintain itself,” he stressed.
For operations and functionality management work, the specialist commented that online monitoring of the plant is normally offered, especially if it has CCTV.
“Monthly (or biweekly) monitoring reports are generated showing the performance of the project and the components that are part of the project (substation, measurement booth, connection line, medium voltage network, etc.),” he explained.
In fact, one of the most important parts of operating a business is precisely monitoring all the data and various components that make it up, since the return on investment depends on continuous and reliable energy generation.
Because of this, the use of a Scada system – an acronym in English that means Supervision and Data Acquisition System – can help improve the plant's performance, which can be useful for both GC (centralized generation) and GD (distributed generation).
It is a technology that uses monitoring and supervision software to obtain more detailed information from plants, allowing monitoring, configuration, data storage and resources to be made available so that the owner can intervene manually or automatically in the process, whenever necessary.
In real time, for example, it is possible to view and monitor this information, such as identifying possible energy overloads in inverters.
In the GC segment, it is even possible to change, in just a few seconds, the positioning of the trackers to obtain greater sunlight capture at certain times of the day.
School subjects Can a Scada system improve the profitability of a photovoltaic plant? published in the 10th edition of the magazine, has more details. Visit the website canalsolar.com.br/revista-canal-solar.
Problems arising from the lack of efficient O&M
Often, due to the lack of maturity or even technical knowledge of the client or supplier who will perform the O&M, inadequate execution can lead to undesirable system functioning.
In the midst of this scenario, the operations director of GLD Energy listed the problems commonly encountered with regard to assets. They are:
- Wasps, bees found in inverters, strings and transformers;
- Bird nests in table structures or under panels;
- Rats in the junction boxes;
- Poisonous animals that hide in tall vegetation and feed on rats;
- Soil degradation due to lack of or inadequate drainage;
- Breakage of plates due to pruning of vegetation with inappropriate machinery;
- Microcracks in modules caused by inadequate washing processes.
Regarding generation, in Geraldo Dias' opinion, the most harmful problem is the breakage of modules when pruning vegetation. "When a panel breaks during washing, the problem is quickly noticed and the module is replaced immediately, thus reducing generation costs."
“However, when a panel is broken by a stone, even a small one, thrown by a manual or mechanized brushcutter at the back of the panel, which is a place that is not very visible, this will make it difficult to identify and, therefore, it will take longer to replace it, thus causing a loss of generation,” he explained.
In addition, he cited other problems that cause loss in energy generation, such as:
- Failure to follow equipment manufacturers' instructions regarding the frequency of retightening screws on energized connections;
- Detailed investigation of systemic failures of equipment and components;
- Dirt level of modules above expected;
- Low frequency of washing the panels.
According to Dias, the consequences of these occurrences can cause a fire or even the burning of equipment. When replacing a piece of equipment is necessary, other components in the surrounding area must be analyzed to ensure that they have not also been affected.
“The low frequency of washing the panels may not be affecting the expected generation, but the accumulation of excessive dust and dew will encrust the panel, subsequently generating the need for aggressive washing, which could cause micro-cracks and void the warranty,” he added.
In his view, the way to avoid or mitigate as much as possible is to define the maintenance plan in detail, including the necessary frequency and the correct tools to carry out the actions.
“Furthermore, good plant operation involves using equipment that is not rotary, such as a knife/wire for clearing, but rather a brush, and that does not come into contact with the module for cleaning,” he explained.
It is essential that there is also a weekly visual inspection to check for dirt on the plates, height of vegetation, presence of animals, birds and insects housed, as well as inspections of the generation system as indicated in the datasheet of each piece of equipment and indication of current standards.
“We should not save on O&M. When designing the project, we should already use CAPEX (plant implementation cost) with components that will increase the project’s useful life with low OPEX (operating cost),” he concluded.
How much does the O&M of a PV plant cost?
Having said the concept and the activities that guide the O&M plan, it is time to say how much it costs to acquire such services. According to experts, it is a little difficult to price, as this is linked to the physical size of the system (generation power), whether it will be a rooftop or ground-based plant, and also the deadline for accepting the team's services.
Kleber Alota commented that, normally, for a 5 MW ground plant, at least two people are hired (electrician and assistant) for day-to-day work.
“When there is a longer intervention (cutting vegetation, cleaning the land and washing the modules), the team increases seasonally to carry out the actions described in the O&M tasks,” he said.
“Therefore, for a plant with 5 MW of installed capacity, where we will have 2 full-time operators (administrative hours), the monthly value can vary from R$28.000 to R$35.000”, he reported.
O&M projects gain importance in the sector
With the huge growth of solar systems installed on rooftops, ground and carports, Alota stressed that issues related to plant maintenance are gaining a lot of attention, evidenced by efforts made by various institutions and companies, which aim to develop best practices for operations.
“Many of the problems mentioned can be mitigated through O&M procedures that help identify potential failures, resulting in an increase in the plant's useful life with visual inspections, thermography on modules/inverters (which can be done using drones, for example), cleaning, IV curve measurements and data monitoring,” he pointed out.
According to him, the reliability of a good O&M program (seasonality) for solar plants can prevent major financial losses, as well as guarantee the functionality of operations throughout the system's useful life.
“In order for us to increase energy generation, have equipment and systems operating properly and maintain the expected revenues from our plant, O&M activities have proven to be fundamental and essential, as well as representing a large (expanding) market with high potential for future business and growth,” he emphasized.
Elvis Almeida also sees that O&M projects have been gaining more importance in the solar sector, as the number of medium and large-scale plants has grown.
“The operation and maintenance of a plant are mandatory items within the project, since photovoltaic projects have a long life cycle”, concluded the Director of New Business at MySol.
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