Utility Scale O&M Practices

India has been moving ahead aggressively with an ambitious programme to reach an installed capacity of 100GW solar power by 2022. Many states are setting up Multi-megawatt solar power installations to herald the arrival of the renewable energy generation. Solar Power Plants are built to last 25 years or more. However, after the Engineering Procurement & Construction period is completed, the Operations & Maintenance (O&M) activities have to be seamless and a well-oiled exercise. This ensures that energy generation is in the expected range through the decades, though there is an expected degradation of about 4-6% in panel output after a decade. These plants need to be maintained to ensure sustainable energy generation.

Contrary to popular belief, that solar power plants are not maintenance free; they too require a regimen of periodic inspection, continual monitoring, service calls and scheduled preventive maintenance. These actions address unplanned outages, repair and restart, and various O&M activities needed to enhance performance, long term uptime and economic viability. Though, PV O&M practices are still emerging and evolving, a number of utilities and third party service providers are working on these practices and developing a better sense of what level is required for system- and site-specific costs and benefits.

According to the report from GTM Research, the global market for utility-scale PV and operations & maintenance (O&M) will reach 200GW-220GW by the end of 2017. The figure represents a 40% annual increase in deployments over 2016. The report notes that more than half of the addressable market has been deployed in the last two years alone. In fact, only 5 percent of the total global capacity has been operating for more than five years. However, the pace of annual installations is expected to drop in 2017 due to a contraction of the Chinese market.

Forecasts estimate that by 2021, China will represent 35% of the global installed capacity for large-scale PV plants, with the US the second biggest market at 20%, followed by India at 13%. ‘‘New construction markets like the U.S. and India feature large plant sizes and consolidated ownership landscapes that result in very large portfolio sizes,” says Cedric Brehaut, lead author of the report. GTM Research identify the five major goals of solar O&M throughout its report:

• Optimization of plant production for increased asset revenue

• Reduction of risks for asset owners and investors

• Protection of asset value and longevity

• Compliance with applicable regulations (e.g., those set forth by the grid operator or environmental governance bodies)

• Transparency on plant production, performance, issues, risks and O&M activities

Rising Importance of Growing Utility Scale Solar O&M Practices

The Indian solar industry has grown dramatically in the last few years. Cumulative installed solar capacity has reached 9GW and the amount of solar installed annually has continued to grow. As the number of installations has increased, the average size of Utility-scale solar facilities has increased as well. Just as the industry is evolving, so are the best practices. The increased size and number of systems has led to the development of portfolio O&M strategies, and a greater focus on efficiently maintaining solar facilities.

As the solar industry continues to grow and evolve, corrective strategies for operations and maintenance (O&M) are being replaced with more advanced preventative and condition based regimes. There are several major approaches for handling the O&M of solar PV systems that exist in the marketplace today, each with different system efficiency and system/component lifespan. At their core, each approach, listed below, attempts to achieve the three key aims of an effective O&M strategy: to reduce costs while improving availability and increasing productivity.

Preventative Maintenance (PM) entails routine inspection and servicing of equipment to prevent breakdowns and unnecessary production losses. PM regimes are becoming increasingly popular because of their perceived ability to lower the probability of unplanned PV system downtime.

However, the upfront costs associated with PM programs are moderate and the underlying structure of PM can engender superfluous labor activity. In addition, increased inspection and maintenance activity has the potential to contribute to site wear and tear and perversely expedite system malfunctions.

Corrective or Reactive Maintenance addresses equipment breakdowns after their occurrence and, as such is instituted to mitigate unplanned downtime. The current industry standard, this “break fix” method allows for low upfront costs, but also brings with it a higher risk of component failure and accompanying higher costs on the backend (putting a premium on negotiating beneficial warranty terms). Though a certain amount of reactive maintenance will likely be necessary over the course of a plant’s 20-year lifetime, it can be lessened through more proactive PM and condition-based maintenance (CBM) strategies.

Condition-based Maintenance (CBM)

uses real-time data to prioritize and optimize maintenance and resources. Though largely incipient, an increasing number of third party integrators and turnkey providers are developing CBM regimes to offer greater O&M efficiency. The increased efficiency, however, comes with a high upfront price tag given the communication and monitoring software and hardware requirements. Moreover, the relative novelty of CBM can produce maintenance process challenges caused in part by monitoring equipment malfunction and/or erratic data connection. On the whole, the PV segment is trending toward O&M approaches that promote greater oversight and management capability. Based largely on budgetary constraints and the relatively low level of importance assigned to PV production (which represents a small fraction of the generation portfolio), utilities are employing—either directly or via a third-party, a combination of PM and reactive maintenance strategies. However, CBM is anticipated to play a larger role as PV assets proliferate, associated information technology and deployment costs fall, and the overarching cost-benefit equation improves. Somewhat unsurprisingly, nascent CBM efforts are being predominately developed by third-party monitoring and services providers whose livelihoods have historically been more closely aligned with PV system performance metrics.

Important Attributes for Providing Reliable O&M Services

Location

Solar Power plants are usually installed in remote areas because of the low cost of the land and an added benefit of good insolation for the amount of solar radiation reaching a given area. O&M Vendor should have a committed team to tackle all the issues and able to reach the service team of the equipment OEMs in case of major faults that can lead to break downs. Availability of JCBs on rent for addressing transformer failures and other major break downs will be handy; machine repair outlets needs to be identified in these remote locations where one can work on machining critical parts. It could be a potential ingredient for losses, if such a facility is not in the vicinity.

Moreover, presence of a client representative in the premises can help in communication being seamless and ensure better O&M services being provided by vendor and tasks can be prioritized. Periodic visits by the O&M team management needs to be there to the far flung sites to ensure that their field personnel are motivated enough to work and offer the client continuous and reliable O&M services.

Inventory

It is recommended that a healthy Spare & Consumables inventory is the key to ensure smooth operations whenever break downs occur; appropriate replenishment of inventory is required at re-order levels. A good understanding between client and vendor is necessary as to which of the items’ inventory will be handled by the client, especially the costly spares and which of the items by the vendor. Client has to be prepared more than the vendor in this area as some critical spares may be costly and the O&M provider may not necessarily have enough resources to procure these at short notice. Some clients prefer to handle this area as their responsibility as they can control the inventory & costs through bulk purchases being made for their plants across the country. Usually clients with a good ERP system can help the vendor in this exercise, otherwise there can be a gap seen in this area.

Training

Training for the O&M team is very vital to provide better O&M services. With the kind of growth likely in the solar space, India needs trained manpower to man these private/government plants. India lacks good vocational and skilled hands. There are few institutes in the country offering expertise in the Solar Power plant training. O&M providers are sometimes motley of petty contractors providing maintenance with semi skilled staff while some providers deploy best in class practices but juggle around with a few trained staff. Plants are set up across the country side and one has to rely more on local labor to do the work as that will be beneficial for the vendor to avoid employee turnover. The local populace in many states may not be exposed to working in MWp size plants. Technicians from other parts of the country would have to move in to work in these remote areas to fill in the gap – mostly those with a passion for the field only take up such opportunities. Building up a sound O&M team at each site gives the client the confidence that the plants are in safe hands and can be run independently by the vendor. In any case, training on technical, safety measures is important for the success of O&M activities at the plant. Training programmes, especially on the Inverters, High Tension (HT) side can be very useful in the long run.

Safety & Security

Safety should encompass safe working practices like Lockout/Tag out procedures, safe handling of venomous snakes & scorpions that may be residing in the plant premises. Hospitals near the plants should stock reasonable quantity of anti venom and emergency numbers of the hospital staff should be readily available. Fire handling capability is also a significant requirement, which the O&M provider has to be prepared for. The client on their part should ensure that a few of the personnel at site are well versed on Cardiopulmonary resuscitation (CPR) to handle medical emergencies. Security needs to be tight as thefts are not uncommon in such utility plants. Copper in the cables are usually the target. Security team has to patrol sensitive areas close to the boundary of the plant bordering villages when cases of vandalism arise. Electric fencing and cameras at vantage positions may be an option to go for.

Module Cleaning & Vegetation Growth

Water availability for cleaning is very important as it is a prime fixture in O&M activities. Periodic cleaning is preferred by clients to ensure good irradiance and thereby better energy generation. Avoiding major construction activity during the post EPC phase can be helpful for the Module cleaning activities as the dust level in the plant will be minimal. However, it is more a wish and it never materializes as many infrastructure issues surface 3-6 months after EPC and may involve the EPC vendor’s services for a longer time.

Vegetation growth is always a concern in solar plants as shadow effects can bring down generation. So trimming the vegetation growth all year around may be necessary, particularly after the monsoons. This will require clearing grass growing across large acreage of land. More mechanization in this area can help otherwise conventional methods of grass cutting using labor will be relatively slow and may be costly. With labor rates going up across the country the cost of clearing acres of grass can hit bottom lines of the O&M provider.

System Monitoring

Continuous monitoring is required of plants performance, and more analytical information can be built rather than plain reporting. This requires uninterrupted communication of data, as major technical glitches during the time of data disturbances will not be known and may be catastrophic, if it occurs during that interval. The internet system should be stable and reliable to provide for effective monitoring. A SCADA system with provision for string level monitoring is ideal though costs can be prohibitive for certain clients, who may just go in for String Combiner Box (SCB) level and inverter level monitoring. The speed of addressing issues and resolving them will go down, if string level monitoring is not available. Auxiliary supply should be always available for the SCADA system. The O&M provider has to ensure that these are addressed in the Preventive maintenance activities.

Technical Aspects

These are the most critical areas, which need attention all throughout the year. The heart of any Solar Plant is the inverter. More reliable the inverters, easier the O&M exercise. Otherwise the O&M provider has to live with unreliable inverter(s) and spend more time and money on repairs or encounter frequent break downs. It all boils down to the warranty support in the first few years. If the support is erratic, then the O&M provider will be unable to help the client in their energy generation expectations. A proper hand off from the client/EPC provider to the O&M provider in the post EPC stage will go a long way in stream lining O&M activities. Otherwise the lingering EPC problems, mainly the technical ones potentially can stall operations, if it had been neglected or passed off as minor issues by the EPC vendor. The client has to be supportive of the O&M provider and have a clear cut process for the hand off. Module damages are common and result in loss in energy generation. Stress related damages to ‘Thin film modules’ are seen in tropical conditions and needs to be studied in detail. Moreover, the availability of technology driven tools like ‘Thermal Imager to detect string faults, early module damages, heating problems in inverters and Cable fault detectors to detect cable faults quickly can be very helpful to contain downtimes and generation losses. The importance of O&M is often overlooked by many developers. Considering the fact that the plant has to generate returns over a period of 25 years, a good O&M contractor, a good monitoring system and above all, a very good O&M process is very critical for the success of the plant. Understanding the cure for Utility Scale Solar Plants leads to a better evaluation of Operating and Maintenance Practices. Of course, the process sounds problematic if the O&M service provider is not well equipped and prepared, but with the latest technological advancements and methodologies- the task seems achievable now.