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301 Moved Permanently

301 Moved Permanently


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Operations and maintenance (O&M) for utility-scale photovoltaic projects is emerging as a topic of considerable interest with the growing number of PV installations. As with any technology, O&M develops and improves with experience. And as PV projects become increasingly prevalent, O&M practices will need to continue to evolve further to mitigate downtime and lost revenue, as well as reduce operating cost.

The O&M agreement forms the foundation of the relationship between the owner and the O&M contractor. A well-structured O&M agreement clearly outlines the scope of services and associated cost, owner and contractor responsibilities, and any availability or performance guarantees.

A minimum scope of services for an O&M contractor should include basic preventive maintenance that keeps equipment in good functioning condition and follows the recommendations of equipment suppliers. The following list is a selection of these basic maintenance tasks and typical frequency for performance.

O&M agreements for PV facilities generally assign a fixed fee for the defined scope of services depending on the technology used, capacity and location. The O&M agreement also identifies a procedure for approving work outside of the scope of services and rates or costs associated with additional work.

 

The owner and O&M

Common responsibilities of the owner include the following:

The O&M contractor’s responsibilities, apart from providing the basic scope of services, often include the following:

A common element of O&M agreements is to include guarantees for availability and/or performance. An availability guarantee requires the O&M contractor to maintain the project such that it is capable of operating a certain percentage of daylight hours. A common minimum threshold for an availability guarantee is 97% of the hours when there is sufficient solar irradiance to generate electricity. Although such levels are typical for guarantees, an availability of at least 99% is generally expected for professionally maintained PV projects operating in North America.

A performance guarantee requires the O&M contractor to operate and maintain the project such that a certain level of energy production is achieved in a given 12-month period. The actual production is compared to estimated energy production, adjusted based on actual conditions experienced at the project. Generally, a guarantee of at least 95% of the adjusted production estimate is typical for utility-scale PV projects. However, this level should be carefully considered, as each project is unique.

Also, depending on the size and location of the project, the O&M organization may take different forms. One significant consideration for the O&M organization is whether staff will be located on-site full-time or if the project will be remotely monitored with resources dispatched as necessary.

 

Budgets will develop to become more effective based upon more accurately quantified costs.

 

O&M structure

Successful O&M work requires that the contractor have comprehensive programs and procedures that guide orderly operation of the PV project. The O&M contractor should have general operational, safety and environmental procedures that are customized to each specific PV project. Further, the O&M contractor should have equipment maintenance plans, security plans and spare parts plans. Finally, the O&M contractor should have a computerized maintenance management system to manage work orders, dispatches, warranty repairs, maintenance logs and spare parts inventory.

Staffing requirements will be specific to the size and technology used for a PV project. Generally, the staffing structure should include a plant manager, an O&M manager and technicians.

The plant manager should be responsible for overall O&M, budget, staffing, performance and policy, and program management. The plant manager may also be responsible for managing the O&M contract, handling O&M-related requirements of the interconnection and power purchase agreements, and overseeing equipment warranties.

The O&M manager should be responsible for the implementation and scheduling of O&M activities and the direct management of technicians. This individual may be suitably trained to provide support to the project as necessary in the event of a technician’s absence.

Technicians with a mix of electrical and mechanical backgrounds should be trained and certified, as needed, to preserve warranties, particularly in the case of inverters and module installation.

Contract services may be used to supplement assigned staff when specialty services (e.g., infrared scans, inspections and maintenance of the interconnection or instrument calibration) or labor-intensive tasks need to be performed (e.g., module washing, ground maintenance). Depending on the requirements and size of the PV project, a full-time environmental representative may also be necessary.

 

Budget considerations

As more utility-scale PV projects accumulate operating time, budgets will develop to become more effective based upon more accurately quantified costs and the variables that drive those costs.

A budget will be highly dependent on the project size, design and location. However, considerations for an O&M budget should include the fixed fee of the O&M contractor’s services, a budget of additional services outside the O&M contractor’s scope and funds for equipment maintenance. Consideration should be made for module replacement, repair or refurbishment of inverters, tracker maintenance (if applicable), substation equipment maintenance and a spare parts inventory.

O&M reserve funding has evolved in recent years and is typically focused on inverter repair, refurbishment and/or replacement. Certain PV module technologies (particularly crystalline silicon) have significant field operating history and long-term warranties. However, utility-scale inverters have yet to be widely confirmed over the typical 25-year useful life of a PV project, and manufacturers generally offer a warranty of only five to 10 years. O&M reserve funding should also take into account other major maintenance considerations, such as transformer and substation repair and/or component replacements, as well as balance-of-plant components.

An adequate spare parts inventory can ensure the minimum amount of downtime in the event of component failure. Spare inventories should consider manufacturer-recommended maintenance, as well as unplanned corrective maintenance.

Although module warranties are typically 25 years or more, it is recommended that spare modules be available in the event of failure or breakage that is not covered by the warranty. For large PV projects, spare transformers and substation collection circuit breakers may be kept in inventory to maximize uptime.

Overall, proper O&M practices are critical to any utility-scale PV project in order to mitigate downtime and maximize revenue. With continued development and experience, industry standardization of O&M practices will continue to mature. S

 

Heidi Larson is a renewable energy engineer at SAIC specializing in solar power generation, with experience in renewable energy generation, energy efficiency and sustainable solution development. Sean McPherson is also a renewable energy engineer at SAIC, with more than seven years of PV design and integration experience as a project manager and North American Board of Certified Energy Practitioners certified installer.

Industry At Large: Utility-Scale Projects

Help For Getting A Handle On Large-Scale Solar O&M Relationships

By Heidi Larson & Sean McPherson

With continued development and experience, industry standardization of O&M practices will continue to mature.

 

 

 

 

 

 

 

 

 

 

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