Operation & Maintenance – Best Practice Guidelines / Version 4.0 – Dec 2019


Welcome to Version 4.0 of SolarPower Europe’s Operation & Maintenance (O&M) Best Practice Guidelines. This new version produced by SolarPower Europe’s O&M and Asset Management Task Force, led by BayWa r.e., has achieved a very high level of maturity and is now well established as a reference in the solar sector. It builds on the previous versions, led by First Solar and subsequently Alectris, and has been further fine-tuned and upgraded with the help of leading experts that joined our Task Force in 2019.

O&M is a segment of great importance for the solar industry in Europe and worldwide. It is the segment that creates the most jobs and economic value in Europe, and drives important solar innovations globally notably in the field of digitalisation and data processing. The first version of these Guidelines was published in 2016 to address service quality issues in solar O&M and by 2019, the guidelines have become a living document powered by an active community of experts.

The Version 4.0 provides updates which are considered important to keep pace with the fast development of the industry. We thank our members, as well as partners including the Solar Trade Association (STA) and the National Renewable Energy Laboratory (NREL), for the thorough review. For example, in the chapter on Data and Monitoring requirements updates were incorporated to reflect state-of-the-art communication technology and cybersecurity requirements. We also included an overview of existing international standards in the field of solar O&M, and new innovative field inspection techniques such as fluorescence imaging and magnetic field imaging. In the Key Performance Indicators (KPIs) chapter, we added an explanatory section on how to interpret Performance Ratio and included new KPIs such as Trackers Availability and Schedule Attainment. We have updated the Contractual Framework chapter according to the Open Solar Contracts, which were published by IRENA and the Terrawatt Initiative in June 2019. We have also aligned the chapter on Technical Asset Management with our new Asset Management Best Practice Guidelines. Last but not least, we improved the user-friendliness of the report by adding new figures and streamlining the document’s structure.

In terms of spin-off activities, 2019 was a very rich year. Most importantly, we completed our well-established O&M Guidelines with the development of Asset Management Best Practice Guidelines, a new report looking at the commercial and financial management of solar investments. The Asset Management Best Practice Guidelines address the professionalisation of solar investors and the globalisation of solar investment portfolios, which lead to rapidly rising service quality expectations that put increasing requirements on solar asset managers. As part of our efforts to disseminate the best practices in Europe and beyond,after publishing a Spanish-language Mexican edition in cooperation with ASOLMEX and the German development cooperation GIZ in 2018, this year, we translated the O&M Best Practice Guidelines into German. We are also working on a French translation for the Tunisian market and an adaptation for the Indian market in cooperation with the German development cooperation GIZ and the National Solar Industry Federation of India (NSEFI). Moreover, we have launched www.solarbestpractices.com, a platform which collects all our reports and tools for quality solar service provision, including the Best Practice Guidelines in all available languages and self-evaluation checklists for O&M contractors, monitoring tool providers and aerial thermography providers. Theplatform also features a directory of companies that comply with the best practices.

We thank our members for their extraordinary level of engagement, which reflects the importance of O&M and Asset Management for our sector. We will continue the work in 2020 and invite interested stakeholders to join our Task Force activities and help us improve even further our contribution to even more performant solar O&M services.


Operation and Maintenance (O&M) has become a standalone segment within the solar industry and it is widely acknowledged by all stakeholders that high-quality O&M services mitigate potential risks, improve the Levelised Cost of Electricity (LCOE) and Power Purchase Agreement (PPA) prices, and positively impact the return on investment (ROI). Responding to the discrepancies that exist in today’s solar O&M market, the SolarPower Europe O&M Best Practice Guidelines make it possible for all to benefit from the experience of leading experts in the sector and increase the level of quality and consistency in O&M. These Guidelines are meant for O&M contractors as well as investors, financiers, asset owners, asset managers, monitoring tool providers, technical consultants and all interested stakeholders in Europe and beyond.

This document begins by contextualising O&M, explaining the roles and responsibilities of various stakeholders such as the Asset Manager, the Operations service provider and the Maintenance provider and by presenting an overview of technical and contractual terms to achieve a common understanding of the subject. It then walks the reader through the different components of O&M, classifying requirements into “minimum requirements”, “best practices” and “recommendations”.

Environment, Health & Safety

Environmental problems are normally avoidable through proper plant design and maintenance, but where issues do occur, the O&M contractor must detect them and respond promptly. Environmental compliance may be triggered by components of the PV system itself, such as components that include hazardous materials and by-products that may be used by the O&M contractor such as herbicides and insecticides.

In many situations, solar plants offer an opportunity to provide for agriculture and are a valuable natural habitat for plants and animals alongside the primary purpose of power production. Solar plants are electricity generating power stations and have significant hazards present which can result in injury or death. Risks should be reduced through proper hazard identification, careful planning of works, briefing of procedures to be followed, documented and regular inspection, and maintenance. Personnel training and certification and personal protective equipment are required for several tasks. Almost all jobs have some safety requirements such as fall protection for work at heights and electrical arc-flash, lock-out tag-out, and general electrical safety for electrical work; eye and ear protection for ground maintenance.

Personne& training

It is important that all O&M personnel have the relevant experience and qualifications to perform the work in a safe, responsible and accountablemanner. These Guidelines contain a skills’ matrix template that helps to record skills and identify gaps.

TechnicaAsset Management

Technical Asset Management (TAM) encompasses support activities to ensure the best operation of a solar power plant or a portfolio, i.e. to maximise energy production, minimise downtime and reduce costs. In many cases, the O&M contractor assumes some technical Asset Management tasks such as planning and reporting on Key Performance Indicators (KPIs) to the asset owner. However, in cases where the technical asset manager and the O&M contractor are separate entities, close coordination and information sharing between the two entities is indispensable. Technical Asset Management also includes ensuring that the operation of the PV plant complies with national and local regulations and contracts, and also advising the asset owner on technical asset optimisation via e.g. repowering investments. For more information about Asset Management, please refer to SolarPower Europe’s Asset Management Best Practice Guidelines, which can be downloaded from www.solarpowereurope.org

Power Plant Operation

Operation is about remote monitoring, supervision and control of the PV power plant and it is an increasingly active exercise as grid operators require more and more flexibility from solar power plants. Power plant operation also involves liaising with or coordination of the maintenance team. A proper PV plant documentation management system is crucial for Operations. A list of documents that should be included in the as-built documentation set accompanying the solar PV plant (such as PV modules’ datasheets), as well as a list of examples of input records that should beincluded in the record control (such as alarms descriptions), can be found in the Annex of these Guidelines. Based on the data and analyses gainedthrough monitoring and supervision, the O&M contractor should always strive to improve PV power plant performance. As there are strict legal requirements for security services in most countries, PV power plant security should be ensured by specialised security service providers.

Power Plant Maintenance

Maintenance is usually carried out on-site by specialised technicians or subcontractors, according to the Operations team’s analyses. A core element of maintenance services, Preventive Maintenance involves regular visual and physical inspections, functional testing and measurements, as well as the verification activities necessary to comply with the operating manuals and warranty requirements. The Annual Maintenance Plan (see an example in Annex B) includes a list of inspections and actions that should be performed regularly. Corrective Maintenance covers activities aimed at restoring a faulty PV plant, equipment or component to a status where it can perform the required function. Extraordinary Maintenance actions, usually not covered by the O&M fixed fee, can be necessary after major unpredictable events in the plant site that require substantial repairworks. Additional maintenance services may include tasks such as module cleaning and vegetation control, which could be done by the O&M contractor or outsourced to specialist providers.

Revamping and repowering

Revamping and repowering are usually considered a part of extraordinary maintenance from a contractual point of view – however, due to their increasing significance in the solar O&M market, these Guidelines address them in a standalone chapter. Revamping and repowering are defined as the replacement of old, power production related components within a power plant by new components to enhance the overall performance of the installation. This chapter presents the best practices in module and inverter revamping and repowering and general, commercial considerations to keep in mind before implementation.

Spare Parts Management

Spare Parts Management is an inherent and substantial part of O&M aimed at ensuring that spare parts are available in a timely manner for Preventive and Corrective Maintenance in order to minimise the downtime of a solar PV plant. As a best practice, the spare parts should be owned by the asset owner while normally maintenance, storage and replenishment should be the responsibility of the O&M contractor. It is considered a best practice not to include the cost of replenishment of spare parts in the O&M fixed fee. However, if the asset owner requires the O&M contractor to bear replenishment costs, the more cost-effective approach is to agree which are “Included Spare Parts” and which are “Excluded Spare Parts”. These Guidelines also include a minimum list of spare parts that are considered essential.

Data and monitoring requirements

The purpose of the monitoring system is to allow supervision of the performance of a PV power plant. Requirements for effective monitoring include dataloggers capable of collecting data (such as energy generated, irradiance, module temperature, etc.) of all relevant components (such as inverters, energy meters, pyranometers, temperature sensors) and storing at least one month of data with a recording granularity of up to 15 minutes, as well as a reliable Monitoring Portal (interface) for the visualisation of the collected data and the calculation of KPIs. Monitoring is increasingly employing satellite data as a source of solar resource data to be used as a comparison reference for on-site pyranometers. As a best practice, the monitoring system should ensure open data accessibility in order to enable an easy transition between monitoring platforms and interoperability of different applications. As remotely monitored and controlled systems, PV plants are exposedto cybersecurity risks. It is therefore vital that installations undertake a cyber security analysis and implement a cybersecurity management system. To evaluate monitoring tools it is recommended to refer to the Monitoring Checklist of the Solar Best Practices Mark, which is available at http://www.solarbestpractices.com.

Key Performance Indicators

Important KPIs include PV power plant KPIs, directly reflecting the performance of the PV power plant; O&M contractor KPIs, assessing the performance of the O&M service provided, and PV power plant/O&M contractor KPIs, which reflect power plant performance and O&M service quality at the same time. PV power plant KPIs include important indicators such as the Performance Ratio (PR), which is the energy generated divided by the energy obtainable under ideal conditions expressed as a percentage, and Uptime (or Technical Availability) which are parameters that represent, as a percentage, the time during which the plant operates over the total possible time it is able to operate. O&M contractor KPIsinclude Acknowledgement Time (the time between the alarm and the acknowledgement), Intervention Time (the time between acknowledgement and reaching the plant by a technician) and Resolution Time (the time to resolve the fault starting from the moment of reaching the PV plant). Acknowledgement Time plus Intervention Time are called Response Time, an indicator used for contractual guarantees. The most important KPI which reflects PV power plant performance and O&M service quality at the same time is the Contractual Availability. While Uptime (or Technical Availability) reflects all downtimes regardless of the cause, Contractual Availability involves certain exclusion factors to account for downtimes not attributable to the O&M Contractor (such as force majeure), a difference important for contractual purposes.

Contractual framework

Although some O&M contractors still provide Performance Ratio guarantees in some cases, it is a best practice to only use Availability and Response Time guarantees, which has several advantages. A best practice is a minimum guaranteed Availability of 98% over a year, with Contractual Availability guarantees translated into Bonus Schemes and Liquidated Damages. When setting Response Time guarantees, it is recommended to differentiate between hours and periods with high and low irradiance levels as well as fault classes, i.e. the (potential) power loss. As a best practice, we recommend using the O&M template contract developed as part of the Open Solar Contracts, a joint initiative of the Terrawatt Initiative and the International Renewable Energy Agency (IRENA). The Open Solar Contracts are available at http://www.opensolarcontracts.org.

Innovations and trends

O&M contractors are increasingly relying on innovations and more machine and data-driven solutions to keep up with market requirements. The most important trends and innovations shaping today’s O&M market are summarised in this chapter, grouped into three “families”: (1) Smart PV power plant monitoring and data-driven O&M, (2) Retrofit coatings for PV modules, and (3) O&M for PV power plants with storage.

O&M for distributed solar

All best practices mentioned in these Guidelines could be theoretically applied to even the smallest solar system for its benefit. However, this is not practical in nature due to a different set of stakeholders and financial implications. This chapter assists in the application of the utility-scale best practices to distributed solar projects, which are shaped by three important factors: (1) a different set of stakeholders – owners of distributedsystems not being solar professionals but home owners and businesses, (2) different economics – monitoring hardware and site inspections accounting for a larger share of investment and savings, and (3) a higher incidence of uncertainty – greater shade, lower data accuracy and less visual inspection.

About Ritesh Pothan

Ritesh Pothan, is an accomplished speaker and visionary in the Solar Energy space in India. Ritesh is from an Engineering Background with a Master’s Degree in Technology and had spent more than a decade as the Infrastructure Head for a public limited company with the last 9 years dedicated to Solar and Renewable Energy. He also runs the 2 largest India focused renewable energy groups on LinkedIn - Solar - India and Renewables - India
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