Operational and maintenance of Solar plant

Operation and Maintenance of Solar Plants Operations and maintenance plays a critical role in deciding the lifetime of solar power plants. Contrary to popular belief that in comparison with most other power generating technologies, PV plants have low maintenance and servicing requirements, is a thing of past. At present in order to maximize the life of the system, it requires a regimen of continual monitoring, periodic inspection, scheduled preventive maintenance, and service calls. Grid-connected solar photovoltaic (PV) systems are expected to proliferate over the coming decade and higher penetration levels will put a premium on achieving optimal performance and reliability. Also since solar energy is based on power purchase agreements that run for up to twenty years, it is vital that renewable electricity facilities remain efficient and viable over the long term. To support these long-term projects, there is a need of utilities and third party service providers to work on developing a better sense of system and site specific costs and benefits. Concept of O&M of Solar PV Plant Once your solar park has been commissioned, there are few efforts that has to be made in order to enhance the span of the plant, one usually enters into a contract with a suitable counter party to undertake operation and maintenance (O&M) or as in many cases this may be fulfilled by the original EPC contractor. One of the major aspects of the O&M contract will be continuous monitoring of the performance of the plant and all of its primary subsystems, which is normally undertaken remotely. This enables performance to be compared with the anticipated output under the climatic conditions actually experienced. It also provides data to enable the scheduling of both rectification and preventative maintenance. Apart from monitoring there are efforts made to improve PV performance and reliability in the near- to medium-terms via monitoring, operations procedures, and maintenance techniques.  Maintenance consists of: Warranty Coverage: An Essential O&M Ingredient  Warranty terms that clearly define system performance thresholds and assign responsibility for system repairs, eligibility, and response time requirements are a vital part of a successful O&M program.  There is no such thing as perfect warranty language; there are simply too many potential problems that may arise. However, making stipulations that cover the biggest problem items is an effective approach that can maintain a healthy relationship between plant owners, system managers, EPC contractors, site integrators, and component suppliers—and keep the overall labor costs of warranty enforcement down. Meanwhile, performing rigorous initial site commissioning, to ensure that the sum total of equipment and plant components are functioning correctly can help to guarantee performance adequacy and lessen lifecycle O&M costs. Most integrators provide some form of warranty coverage for the systems they construct—though terms can vary widely—while some localities mandate specific warranty coverage. Inverter warranty coverage, which is improving, is particularly important given their high breakdown rates. Beyond the 10-year industry standard, certain manufacturers like PV Powered offer 20-year coverage. And inverter warranty extensions, though potentially cost prohibitive given project dynamics, are also available to 15 years and beyond. Specific warranty terms, such as the potential need to be trained to inspect a particular inverter for the warranty to hold up, should be carefully reviewed. Separately, most communication components tend to fall under a one-year manufacturer’s warranty, during which time nearly all communication issues tend to arise but be non-critical in nature. Panels, which have a low post project commissioning failure rate have, to date, not caused significant warranty claims. However, of note, vandalized or stolen panels can fall outside of warranty items. Requirements for timeliness, defined according to a “critical” and “non-critical repair” hierarchy, represent an additional layer of warranty coverage. Critical repairs encompass those that affect production or the recording of production, and require immediate action. All other repairs are considered non-critical and do not require immediate action. Given the nature of critical repairs, warranty stipulations can require their resolution within 48 hours of detection or a negotiable time frame  Failure to meet agreed upon resolution deadlines can result in payment by the integrator to plant owners in the amount equal to the calculated revenue lost beyond the repair time frame  Meanwhile, the time frame for resolving non-critical repairs is more relaxed given their lesser priority. Warranty terms specify perhaps a 10-day window of resolution once notification is given to the warranty provider. Failure to meet deadlines can result in a flat, per day penalty payment. The O&M model is shifting As utilities learn more about operating solar power plants, a shift to running operations and operations in-house is emerging. Several major approaches for handling the O&M of solar PV systems exist in the marketplace today, each with different system efficiency and system/component lifespan tradeoffs. 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 “breakfix” 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. The major strategies for O&M include a “corrective maintenance” model. This is the historic method of addressing equipment breakdowns after they occur, which is the current industry standard.  An advantage is lower up-front costs but a back end consequence is a higher risk factor of component failures.  In some studies, the lost production is significant, as 80 percent of the production losses are caused by only 20 percent of the equipment failures. Independent power producers (IPPs) and turnkey PV services companies, responsible for meeting PPA guarantees, are employing novel O&M practices to maximize PV plant output. There has been a wholesale movement to a preventative maintenance strategy to prevent failures before breakdowns occur. These ids of regimes are under development in the industry, but involve more up-front costs. A third, cutting edge is condition based management using real-time data to prioritize maintenance. This method has been spearheaded by third parties to optimize business and bring efficiencies to the process. Whatever method is followed, adoption of best practices are being fine-tuned as solar penetrates a greater share of the utility market.