Photovoltaic Training Course - Module 4.3 - Types of maintenance
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Photovoltaic Training Course - Module 4.3 - Types of maintenance
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Photovoltaic Training Course - Module 4.3 - Types of maintenance
- 1. Photovoltaic Systems Training Plant Maintenance 4.3 TYPES OF MAINTENANCE www.leonardo-energy.org
- 2. Preventive Maintenance Preventive maintenance must: • Be as thorough as possible and as structured as possible. • Be considered during: design, & operation Preventive maintenance must be taken into account during: Plant design Consideration of equipment guarantees Acquisition of components Reception of components When contracting for insurance www.leonardo-energy.org
- 3. Preventive Maintenance During Plant Design • Have the parameters of radiation and tilt of the modules been well studied? • Has the shadowing study been done properly? (Especially if the plant will have suntracking systems) • Has a proper balance been established between losses for shading versus optimization of the plot? • Has a wind study been undertaken? (Especially important in establishing the specifications for suntracking systems) • Are the estimates of plant performance over-optimistic? www.leonardo-energy.org
- 4. Preventive Maintenance During Plant Design • Does outdoor equipment meet IP65 minimum protection level? • Are important components protected by voltage dischargers? • Has the effect of the salinity and humidity of the local atmosphere on the plant’s fixtures and structures been properly studied and accounted for? • Has the quality of the soil been studied to understand any corrosive effects on concrete or fixtures? www.leonardo-energy.org
- 5. Preventive Maintenance During Plant Design • Are control cabinets and control rooms properly ventilated and sufficiently large to dissipate heat and to ensure equipment will be kept sufficiently cool? • Is the section of the cables adapted to avoid voltage drops below the desirable 0.5% - 1%? • Is crucial equipment distributed across the plant to avoid complete production loss in case of fire or flood? www.leonardo-energy.org
- 6. Preventive Maintenance During Component Supply • Are the modules certified by a certified laboratory? • Do the modules fulfill the standard EN 61.215 (or local equivalent standard)? • Are the modules “class II”? • Do the inverters achieve a have European efficiency of 94% - 96 %? • Do the the inverters have suitable galvanic protection? • Are the structures galvanized with a minimum thickness of 80 microns (or equivalent treatment)? www.leonardo-energy.org
- 7. Preventive Maintenance Module Guarantees Nearly all the module manufacturers guarantee a degradation of less than 20 % after 25 years. but … Does the manufacturer guarantee a degradation of less than 10% after 10 years? What guarantees does the chosen manufacturer offer for manufacturing defects? ) (Over 2 years? Closer to 5 years?) NOTE: Pay particular attention to guarantees for thin-film modules. They can suffer strong initial degradation www.leonardo-energy.org
- 8. Preventive Maintenance Equipment Guarantees • Is it the manufacturer or the distributor who offers the guarantee? • If it is the distributor, are they legally established in the country where the plant is built? • If not… does the distributor have the right to export to that market? • Is the guarantee at the end of a “chain of guarantees"? • Does the contract detail all the guarantees adequately? • Have the guarantees for inverters been extended to the maximum number of years (at a reasonable cost)? • Does the manufacturer offer a replacement service, within 24-48 hours? • Does the manufacturer have a hotline service? www.leonardo-energy.org
- 9. Preventive Maintenance During Component Reception • Has a visual inspection been done? • Are components stored in suitable conditions during periods of assembly? • Are spare parts stored in similar conditions? • Where modules are being delivered, have they been classified for electrical testing by power? • Classification of the manufacturer’s “flash list“ can be very useful. • For module tolerances of around 5 %, two classifications can be enough www.leonardo-energy.org
- 10. Preventive Maintenance Before insurance contracts are signed Is there sufficient coverage against risks from: • Atmospheric phenomena • Electrical damage • Theft • Production Losses • Public liability Does the insurance provide reasonable excess? www.leonardo-energy.org
- 11. Preventive maintenance program Training Incident detection Spare parts in the plant Meteorological predictions Grid connection breakdown (Electrical company side) Physical/Remote Surveillance Preventive Maintenance During Plant Operation Are the building blocks in place? www.leonardo-energy.org
- 12. Preventive Maintenance During Plant Operation It is necessary to define the maintenance tasks and their periodicity Then create a record of preventive maintenance for every element, with the date of accomplishment. www.leonardo-energy.org TASK PERIODICITY DATE Cables Check Yearly dd/mm/yyyy Retightening of Electrical Connections Yearly dd/mm/yyyy … … … Example Preventive Maintenance Record
- 13. Preventive Maintenance During Plant Operation General preventive maintenance task list • Earthing system check for transformers and across the facility • Retightening of electrical connections in the control-cabinets • Voltage dischargers check • Cable state check • Module dirtiness check • Suntrackers deviation according to the position of the sun • Lubrication of the components of the suntrackers • Retightening of the suntrackers’screws • Maintenance required by the electrical company in the Transformation Center * * Usually outsourced to the installer of the center
- 14. Preventive Maintenance During Plant Operation Maintenance tasks follow-up Every maintenance task must be logged with individual records for every device or component www.leonardo-energy.org DATE TASK OBSERVATIONS 15/02/2010 Cable checking Routine 06/03/2010 Suntracker lubrication Routine … … … Example Suntracker Record
- 15. Preventive Maintenance During Plant Operation Training Training is really important particularly where maintenance tasks will be kept in-house. The person in charge of plant maintenance must have an adequate foundation in electrical systems and reasonable knowledge of solar power. If the plant has suntrackers, that person must have a good understanding of electromechanical issues. Meteorological predictions Particularly important for plants with suntrackers where the wind can cause considerable damage. Suntrackers should automatically position panels horizontally on receipt of a trigger from the central anemometer It is recommended that each suntracker has its own wind sensor www.leonardo-energy.org
- 16. Preventive Maintenance During Plant Operation Incident detection mechanisms Mechanisms are necessary for the detection of fire in any building: Transformation center Grid isolation center Meter room Control & Supervision Room Grid breakdown detection (Plant-side issues) Incidents caused by the electricity company can cause the plant to disconnect from the grid. It is important to notify key plant staff as soon as possible using: • An acoustic alarm • SMS (particularly important when staff numbers are low, such as at weekends) NOTE: Breakdowns can be unnoticed or even ignored by the electricity company. A system to record and demonstrate the breakdown is important to ensure the plant owners are compensated for loss of energy sales during the breakdown.
Editor's Notes
- Preventive maintenance is the most important type of maintenance because it seeks to avoid costly incidents at a later stage.
- Planning for preventive maintenance starts at the design stage, continues during parts acquisition and plant construction and needs to be taken into account in the plant’s insurance contracts.
- You can’t think of preventive maintenance as a man moving through the plant with his tools. Preventive maintenance must be structured and must take account of all possible incidents on the plant site. During the next slides we will go through a preventive maintenance checklist for a solar project. There are 10 questions to be considered from a preventive maintenance point of view during plant design: First, are the radiation parameters on the site and tilt of the modules well studied? Over-optimistic performance expectations from the site will lead to over-optimistic economic expectations. Second has a proper shadowing study been been carried out that balance shading losses against plot optimisation? For sites using sun trackers, the shading study is an important determinant of plant performance and it should be organized alongside a wind study. Third, the salinity and humidity of the local atmosphere needs to be taken into account as it can influence the life of the selected fixings and support structure.
- Fourth, the quality of the soil needs to be looked at to see if there are soil components that will attack the concrete or erode the fixings. Fifth All equipment to be installed outdoors must have minimum protection for outdoor conditions. Normally that protection level will be IP65. Sixth we have to check that all the important components are protected by voltage dischargers. Seventh check that all control cabinets or rooms have appropriate alarm systems, especially those containing the inverters or transformers. Eighth, check the dimensions of electrical cabinets are large enough to dissipate the heat from the devices inside them during summer months.
- Ninth check cable sections to avoid possible voltage drops. And lastly the tenth it is good design practice to distribute important elements across several isolated rooms to avoid a total loss of production in the case of fire or flood.
- In choosing components special care should be taken over the main elements and the most expensive elements in the solar plant - the modules and inverters. For the modules there are three issues to consider: Are the modules properly approved by a certified laboratory? D o they meet local national standards? If the plant is in Europe the relevant standard would normally be: standard EN 61.215 Third, we have to verify that the modules are class 2. For the inverters we only have to answer 2 questions: First do they achieve a reasonable European efficiency of between 94% and 96%. It is important to check the European efficiency of the inverter rather than the normal efficiency as the Euro efficiency takes account of the load on the inverter. Second Does the inverter have a suitable galvanic protection – at least a thickness of 80 microns. If not, does the inverter have an alternative protection that is at least as effective?
- The level of guarantee on offer from the module manufacturers should also be taken into account. Guarantees over possible module manufacturing defects vary from 2 to 5 years. The length of the guarantee on offer should be checked. Nearly all solar module manufacturers guarantee a degradation of less than 20% over 25 years. However, some manufacturers also offer a guarantee on degradation of less than 10% after ten years. That is better a better guarantee for the performance of our plant than a simple guarantee of degradation of less than 20% after 25 years. The degradation guarantees also need to be taken into account. Guarantees are particularly important for thin film modules as they can suffer strong initial degradation. In fact, some manufacturers don't offer any degradation guarantee on their thin film modules. You should be careful to check that the guarantees against degradation fit with the planned life of your solar plant.
- It is also important to check whether the manufacturer or the distributor is offering the guarantee. Where the distributor is operating as the guarantor, it is important to use a distributor with a legal presence in the country where the plant is being build. If the distributor has no legal presence in that country, verify that they have a right to sell to the country. Any breach of the regulations will have implications for the enforceability of the chain of guarantees that the plant relies upon. Verbal guarantees are not enough. All guarantees need to be properly detailed in the contracts signed with the manufacturer or distributor. For inverters, check that the guarantees can be extended, if desirable, at reasonable cost. A replacement service within 24 to 48 backed up by a helpline that is open over weekends as well as week days, may be the most important service that you look for from the inverter manufacturer
- There are three issues to be considered when you are receiving components: Avisual inspection of all modules received or at least a sample of them; A classification of modules by power using the manufacturer’s class list; and Whether all components have been stored in suitable conditions prior to assembly and and installation. Storage will be revisited later.
- Here are the main issues that must be covered by plant insurance. Atmospheric phenomena Electrical damages Thefts Production Losses Public liability and The level of excess
- Preventive maintenance during plant operation starts with a good preventive maintenance program Next staff should complete comprehensive preventive maintenance training Good monitoring and surveillance for incident detection is vital Spare parts need to be available, accessible and correctly stored, A meteorological station to ensure good weather forecasts is an important tool in preventive maintenance, and Good local or remote security and surveillance systems are important. We will look at these issues in more detail over the next slides.
- In designing a preventive maintenance program, it is imp to define the maintenance tasks and how regularly they should be carried out. Those tasks, their frequency and dates for accomplishment should be defined in a table, that will also provide a log of progress on each task. A more complex table than the one shown here could include notifications or alarms from the monitoring system and a column for the latest date by which a task must be done.
- In this slide we can find a list of features that generally require preventive maintenance: Checking of earthing systems. Tightening of electrical connections in control boxes or control rooms. Checking voltage dischargers and state of cables. Checking the dirtiness of modules and for the appearance of hot spots. Verification that the required maintenance by the electrical companies in the transformation centre has been completed, and If there are suntrackers, a check on their deviation from the optimal position in relation to the sun; and records of tightening and lubrication of moving components.
- Follow-up checks on all preventive maintenance tasks in the program are important, with individual records for each task classified by component. In the example of a sun tracker tasks record, completion dates for each task and whether the task was routine or a response to an incident are included, together with observations on the detection of any malfunction.
- The person with overall responsibility for preventive maintenance must have an understanding of both electrical and solar power issues. If the plant is using sun trackers an understanding of electro-mechanical issues should be added to that list. If the maintenance of inverters or suntrackers is not outsourced, then special it is vital that the personnel are properly trained in the maintenance tasks. Accurate meteorological measures are very important, particularly in plants with sun trackers where the wind can have a major effect on performance. Many sun tracker systems will place modules in a protective position once they receive a warning signal from a central anemomenter. A wind sensor for every sun tracker is a better solution but this can be much more expensive.
- For every potential incident, you will need to establish an incident detection mechanism. In your planning, you should rank every potential incident according to its probability and the damage it might produce. For example, a fire in the control or supervision room is not very probable but the potential damage is severe. Therefore a detection mechanism for that incident is a high priority. Grid connection breaks are often the responsibility of the electricity company that the solar plant supplies. However these breakdowns can sometimes pass unnoticed by the electric company, or even ignored by them. So a detection mechanism that alerts a person with responsibility at the solar plant is important. If the breakdowns are not properly noted or recorded, it could affect the compensation that the solar plant receives.