638.6 kwp Solar Power Plant

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1 SunEdison s 25 MW power plant at Gujarat Solar Park Our 100 kw Rooftop System at Airtel, UP Our 50 kw Rooftop System at Punjab Agriculture University First Canal Top Solar Power Plant at Narmada Canal, Gujarat 1 MW kwp Solar Power Plant Getting your money s worth From a Solar PV plant A white paper BEST SOLAR POWER PRODUCER IPPAI POWER AWARDS 2012 Chennai, Tamil Nadu May 2013

2 Getting your money s worth from a Solar PV plant: based on operational and asset management experience of over 1300 MWs of Solar PV plants Amit Kaushik, Director Energy Analytics, and Renewable Operations Center, SunEdison Energy India Pvt Ltd Introduction Solar PV industry is gearing up for rapid growth in India. The growth will continue as long as a PV project continues to make economic sense for the stakeholders. While, the magnitude of initial capital invested in the PV project plays a big role in the financial feasibility of a solar PV project, the efficiency with which the plant is maintained to maximize energy production will ensure that the PV assets continue to generate maximum cash flows for next 25 years and beyond. Solar PV Plants that are not designed to last and are not operated and maintained well, will suffer from poor performance. Based on rough estimates, a 1% increase in the yield of a solar PV plant can lead to a basis point increase in the project IRR. A 4%-5% improvement in yield is achievable through prior planning for the entire asset lifecycle and focused O&M services after the asset is operational. Levelized cost of energy (LCOE) is a metric commonly used in the industry to compare the cost of energy generated from a solar PV plant with other sources/methods of energy production. LCOE is defined as: LCOE = Currently, there is a strong industry wide focus on minimizing the initial capital invested in developing a solar PV project to minimize LCOE. However, an important and often underestimated lever to reduce LCOE, is maximizing the energy output of an existing PV plant. This can be achieved by careful planning for the entire lifecycle of the asset during the project development phase. This includes design for operability, construction quality, crisp handover between EPC and O&M, robust monitoring platform, and strong O&M. One must also incorporate learning from the operations of existing solar PV plants in Indian conditions in developing future projects. Such a continuous improvement approach where failures are analyzed and lessons learned from them are incorporated in the future projects allows for a systematic improvement in LCOE. About operational assets in India In year 2012, a portfolio of approximately 54 MW (SunEdison s fleet in India) of solar PV assets, experienced 1500 failure events leading to a loss of approximately 3.9% of the total energy produced during the year. These failure areas can be divided into five broad categories:

3 % of Total Energy Lost 1. Inverters related 2. AC Subsystem: All equipment and wiring after the inverter towards the AC side 3. DC Subsystem: All equipment and wiring before the inverter towards the DC side 4. Support Structure: All mechanical (or non-electrical) components that can lead to energy loss. Module mounting structures constitute this category 5. External: All failures beyond the point of evacuation and/or perimeter of the PV plant Figure 1 below demonstrates failure area and cause of failure from these assets; only failure events leading to energy loss in the year 2012 have been incorporated in this analysis. 40% 35% 30% 25% 20% 15% 10% 5% Cause of Failure Vandalism Other Parts/Materials Failure Grid (Fluctuations/Shutdown) Construction Quality 0% AC Subsystem External Inverter DC Subsystem Failure Area Support Structure Figure1: Failure area and cause of failure from a 54 MW portfolio of solar PV assets in the year 2012 Such an analysis offers a tremendous opportunity for developers, EPC, lenders and policy makers to understand the true behavior of solar assets and work in tandem to make solar PV a viable industry. Some of the key aspects of the above analysis are discussed below. Construction Quality The above analysis clearly highlights construction quality issues as one of the foremost causes of energy loss in the PV plants. Interestingly, the analysis carried out above includes most solar PV plants in the first year of their operational lives. A diligent corrective and preventive action plan by the operator should reduce the impact of this issue in the future life of these assets. However, in order to avoid repeating such issues in future projects appropriate preventive plan is required to minimize/eliminate energy losses right from the inception of the asset. Some recommendations are:

4 a) Strong quality assurance plan (QAP) and frequent quality audits during the construction phase: An EPC contractor must clearly define the QAP committed to the owners and appropriate checklists need to be maintained so that quality audits clearly demonstrate if the QAP is being adhered to. Unlike other type of power plants (thermal or Nuclear), Solar PV plants have a relatively very short commissioning period (only a few days for a MW scale plant) which makes it difficult to catch construction related issues during commissioning phase. Hence, some of the construction related defects show up only once the plant starts functioning. This makes it even more important for the EPC contractor to pay extra attention towards developing and following a comprehensive QAP. b) Ensure overlap of O&M operator s mobilization during the construction phase and operators input during design phase. This may be practical only in case of large assets but adds tremendous value in ensuring a healthy tension between the designers, construction managers and the operators. c) Strong defect and workmanship warranties: This is more of a corrective planning measure rather than a preventive planning approach but is still necessary and generally insisted on by the owners from EPC contractors. d) Selection and training of the EPC workforce: The quality of construction is a strong function of the quality of the workforce. No amount of contractual obligations and incentives can ensure quality unless the staff is qualified and trained to deliver quality work. As solar assets continue to get build in remote and geographically distributed areas, maintaining a quality workforce remains a challenge. However, this is an area which needs strong focus by serious EPC players in order to tackle construction quality issues. External failures due to grid fluctuations/shutdown A grid connected solar PV asset without reliable grid availability is a nightmare for the owners. Prior planning during selection of land and sub-station is generally advised during the project development phase. This however, is a macro scale issue and needs to be tackled by appropriate government authorities to make renewable energy flourish in the country. The effect of this issue manifests in many different ways. Not only does it lower the CUF of a solar asset, but undue fluctuation in the grid also leads over-stressing of the inverter and may potentially impact the life of an inverter. From our experience, the grid stability and availability in the Charanka solar park (Gujarat) sets a great example for rest of the country to follow. During the past year of operation, availability of grid at Charanka solar park has been more than 99.5%. Inverter failures During an earlier analysis of failure frequency in [1] and [2], inverters were reported to be the most frequent failure area leading to maximum amount of energy loss. However, the assets considered in [1] and [2] were mostly located in North America and Europe with stable grid conditions and minimal construction quality defects (as the asset life was greater than one year and most of the construction related defects have been taken care of). In the present analysis,

5 inverter failures are third most impactful failure area in terms of energy loss. Most of the failures observed in inverters are IGBT failures while a very small number of firmware related failures are also observed occasionally. From an operator s perspective, the downtime from such failures can be significantly reduced by maintaining appropriate amount of spares and training operators (by the inverter manufacturers) on basic (and even advanced) level servicing of the equipment. It would not be surprising that the rate of inverter failure events in the coming years increases further because of external factors (e.g. grid) leading to early life failures and with the arrival of new inverter vendors with minimal experience in India conditions. Operations, Maintenance and Asset Management During the past two years of operations of solar assets in India, it has become evident that the industry needs to take a comprehensive approach to managing solar assets. Cleaning modules and managing daily preventive checklists, although highly labor intensive activities (especially in larger MW scale assets), constitute only a very small portion of activities required to make solar assets deliver the desired returns. The intention of this paper is not to provide an exhaustive scope of an O&M service provider but to highlight the importance of some of the key elements of the scope of work carried out during the life of the asset: 1. Warranty management: As much as all asset owners would like to avoid finding themselves in situations where field failures occur leading to warranty claims from the manufacturer, such situations are inevitable during the life of an asset. O&M operators providing warranty management services to the owners ought to take a corrective action/preventive action approach (CAPA) to, first contain the problem to avoid further energy loss, and then perform technical failure analysis and advise the owners if warranty claims can be made. A detailed documentation of the events, testing and analysis done either independently or through a third party lab is generally required for any warranty claims to be accepted by the manufacturers. The challenge in handling warranty claims is allocation of the cause to the event and the experience of an O&M operator comes handy in staying prepared for demonstrating that warranty claims are valid. 2. Reporting: Periodic reports provide owners/lenders with the necessary visibility in their assets. A detailed and accurate report allows them to account for every unit of energy that the asset is capable of producing. This includes actual energy produced and energy lost because of each failure event along with detailed root cause analysis of the failures. One of the biggest challenges in KPI (PR, CUF etc) reporting for solar assets is proper handling of data gaps. Data gaps could occur on the account of communication failures in the data acquisition system or, sometimes, because of equipment failures (like meter and weather station). There are various ways to handle the data gaps and appropriate analysis is required to either backfill the gaps (using advanced modeling techniques) or ignore the gaps depending upon the extent of the problem. Besides the data gap problem, other uncontrolled parameters (like temperature gradients within the plant, systematic and random errors in measuring instruments, random shading of modules by

6 stray causes) introduce uncertainties in plant performance reporting. A perfectly operating solar asset can have 3-5% uncertainty in single day performance ratio. A longer time duration (a quarter or a year) performance ratio reduces this uncertainty. Hence, this uncertainty should be kept in mind while doing performance assessment within the same plant between two time periods or between two different plants. An accurate report should reflect this error for the benefit of the owners. 3. Maintenance based on real time monitoring of site conditions (also known as condition based maintenance): This is a relatively newer concept in solar PV assets and allows better efficiencies both in terms of cost reduction and improved energy production. Some of the examples of this approach are modifying the cleaning schedule based on real time soiling losses, scheduling visual checks based on inverter heat sink temperature etc. Such an approach is possible only if the asset is equipped with a robust monitoring and data acquisition system supported by a real time smart alerting engine. For larger sized assets, this is done at the plant location as well as from a remote monitoring center whereas for smaller size assets (like rooftop installations) remote monitoring center is almost always the only way to achieve this. 4. Forecasting: Solar assets require both short term and long term forecasting. SLDCs require next day (short term) forecasting at 15 minute intervals from solar assets. As the solar industry scales up to constitute a substantial fraction of the total energy supply, the forecasting will help SLDCs match solar production with other power plants for efficient load dispatching. With the help of an independent weather forecasting service providers an O&M operator can predict energy production based on past behavior of the solar asset with reasonable accuracy. As performance modeling methods improve short term forecasting accuracy is bound to get better. Long term forecasting is needed by the lenders/owners to correct their financial models for revaluation of the solar asset. A full service operator must be equipped with statistical modeling tools to incorporate system reliability (derived from field failures) into probabilistic production models for accurate long term forecasting. IT infrastructure and software platform as the backbone of solar assets management An end-to-end solar asset management requires best in class data management architecture that is smart and scalable. A large scale solar asset (say a 25 MW plant with string monitoring capabilities) generates approximately 16 GB of time-series data per year. A robust software application should be capable of handling such large amount of data and allow real time troubleshooting and exception handling to detect failures quickly. An O&M operator attends to a failure incident by asking what failed, when it failed, why it failed (root-cause), what is the correction schedule, and what is the level of impact (energy loss and number of equipment failed). Recording all of the above critical information for easy traceability and developing useful business insights through analytics also requires highly customized software tools. In addition, a

7 unified spares management, service ticket management, warranty management applications brings in a complete tool set necessary for an operator to deliver quality service at an optimized cost. The service architecture of such an O&M operator is summarized in Figure 2. Local Plant Weath er Data acquisition system SCADA = ~ Preventative Corrective Ge n. Me Commissioning Util ity Me Network Gear [router, Deskto Field Operations and Maintenance Renewable Operations Center (ROC) Data Collection Project Billing, AR/AP Client Services Asset Management Site Monitoring Analysis Reporting Remote Energy Forecasting & Grid Integration Services Service Figure 2: End-to-end service architecture for solar asset operations Conclusion Often developers and IPPs debate over a buy versus build strategy for O&M services. Irrespective of the choice, the data presented in this paper highlights the fact that the operations during the life of an asset need careful planning and attention. In addition, a systematic approach to building a quality asset and considerations to reduce cost of poor-quality (the cost

8 which may be incurred for the entire life of the asset) during the EPC phase of the asset will ensure that the asset delivers the expected return. When it comes to reliability, the stakeholders must look at system level reliability from operational assets in addition to component level reliability assessment (usually) done based on lab data provided by the manufacturers. This allows for much better assessment of failure risks associated with the system. Vendor selection and provisioning for spares becomes much more effective with this data than simply relying on lab tests on individual components. Acknowledgement Author would like to thank Pashupathy Gopalan and Raju Rajagopalan for reviewing this article and providing valuable inputs to the content. References: [1] Kaushik A., Golnas A., PV system reliability lessons learned from a fleet of 333 systems Reliability of Photovoltaic Cells, Modules, Components, and Systems IV, Proc. of SPIE vol. 8112, 2011 [2] Golnas A., PV System Reliability: An Operator s Perspective, 38 th IEEE Photovoltaic Specialist Conference, June 3-8, 2012, Austin, Texas

9 Global Locations Our 100 kw Rooftop System at Airtel, UP First Canal Top Solar Power Plant at Narmada Canal, Gujarat 1 MW North America Europe Asia Canada Germany China Malaysia Puerto Rico Greece Dubai Singapore United States Italy India Taiwan South America Spain Japan Korea Thailand Brazil Sub Saharan Africa South Africa SunEdison Menon Eternity, 10 th Floor, New #165, Old #110, St.Mary s Road, Alwarpet, Chennai SunEdison 600 Clipper Drive Belmont, CA MEMC 501 Pearl Drive St. Peters, MO