On February 18, 2025, SolarPower Europe, a European solar PV association, released the latest version of its solar PV system maintenance management guidelines, “Operation & Maintenance: Best Practice Guidelines Version 6.0.“

In this column, we will introduce this report and its executive summary.

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Operation & Maintenance: Best Practice Guidelines Version 6.0
18 February 2025

This report is an industry-leading set of recommendations, on how to elevate and maintain quality in the solar PV sector. As solar deployment continues to grow and digital technologies evolve, harmonising best practices is crucial for scaling up solar operations efficiently.

The latest update of SolarPower Europe’s O&M Best Practice Guidelines arrives at a time when the topic of quality is gaining unprecedented importance across the solar PV value chain. This report is the sixth edition of the O&M Best Practices Guidelines. The first version of the O&M Best Practices Guidelines was published in 2016, with the report being regularly updated since then.

All best practices mentioned in these Guidelines are beneficial and relevant for solar PV systems of all sizes. These Guidelines are a key tool for O&M service providers, as well as investors, financiers, asset owners, asset managers, monitoring tool providers, technical consultants, and all interested stakeholders in Europe and beyond.

Within this report, over 30 experts of SolarPower Europe’s Lifecycle Quality Workstream, have illustrated their knowledge and experience from across the solar sector, coming from Operation & Maintenance (O&M), recycling and circularity, waste management, utility-scale solar, and manufacturing backgrounds.

1. Updated chapters
   On solar power plant maintenance, innovation and trends, and data management.
2. New chapters
   On electrical safety, and common tests and inspections.
3. Recommendations
   Deeper exploration on how to sustainably handle end-of-life (EoL) solar panels after a revamping/repowering project.

Next, we would like to introduce the executive summary of these guidelines.

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Executive Summary

High-quality O&M services are key to mitigating risks, lowering LCOE, and maximising ROI in the solar industry

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 levelized 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 service providers 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 contextualizing O&M, explaining the roles and responsibilities of various stakeholders such as operations service providers, asset managers, and maintenance providers, and by presenting an overview of technical and contractual terms to achieve a common understanding of the subject. It then outlines 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 service provider 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 service provider such as herbicides and insecticides.

In many situations, solar plants offer biodiversity opportunities for agriculture, and are a valuable natural habitat for plants and animals alongside the primary purpose of power production. However, 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, briefings 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.

Personnel & training

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

Skilled O&M personnel are the driving force behind safe, seamless, and powerful operations

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 operations also involve 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 be included in the record control (such as alarms descriptions), can be found in the Annex of these Guidelines. Based on the data and analyses gained through monitoring and supervision, the O&M service provider 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 analysis. 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 E) 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 repair works. Additional maintenance services may include tasks such as module cleaning and vegetation control, which could be done by the O&M service provider or outsourced to specialist providers.

Common test and inspections

Common tests and inspections are integral to ensuring the performance, safety, and reliability of PV systems throughout their lifecycle. These activities involve routine and specialised assessments to detect issues, maintain efficiency, and prolong the system’s lifespan. This chapter outlines the primary tests performed during the lifecycle of PV systems, key inspection methods, and industry best practices based on international standards such as IEC 62446.

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.

KPIs are the heartbeat of solar PV performance—measuring efficiency, response, and O&M excellence

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 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 service provider. 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 service provider 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 to enable an easy transition between monitoring platforms and interoperability of different applications. As remotely monitored and controlled systems, PV plants are exposed to 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 www.solarbestpractices.com.

Key Performance Indicators

Important KPIs include PV power plant KPIs, directly reflecting the performance of the PV power plant; O&M service provider KPIs, assessing the performance of the O&M service provided, and PV power plant/O&M service provider 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 can operate. O&M service provider KPIs include 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 service provider (such as force majeure), a difference important for contractual purposes.

All best practices mentioned in these Guidelines are beneficial and relevant for solar PV systems of all sizes

Contractual framework

Although some O&M service providers 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 www.opensolarcontracts.org.

Innovations and trends

O&M service providers are increasingly relying on innovations and more machine and data driven solutions to keep up with market ® Adobe Stock © BayWa r.e. 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 rooftop 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 distributed systems 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.

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This concludes the report of executive summary. For more detailed information, please read the full report.
Link:
https://www.solarpowereurope.org/insights/thematic-reports/operation-and-maintenance-best-practice-guidelines-version-6-0

Acknowledgments: We would like to express our gratitude to SolarPower Europe and all its stakeholders for publishing such a comprehensive report for those involved in the solar PV industry.