Revision as of 17:37, 30 October 2018 by ***** (***** | *****)
1. Establish and Refine Maintenance Plan
Cleaning of solar panels in Ghana as a routine maintenance activity (Source: Lennart Woltering)
After installation of the system an operations manual should be handed over to the producer (see SET UP
Module) by the technology supplier, or service provider. The operations manual includes instructions for operation, maintenance and troubleshooting, along with the contact details of the service provider. Based on this, the service provider and producer should develop a maintenance plan. The producer and the agricultural advisor should revise the maintenance plan regularly.
Checklists are helpful tools to ensure that maintenance is done regularly and properly. For this, the SPIS toolbox has been developed with checklists on the proper maintenance of the PV generator and the irrigation system. The following aspects are important for each of the main components of an SPIS:
- Water source and pump: Solar pumps generally do not need a lot of maintenance if used in clean water, free of sand, sediments or aquatic plant growth. The water source therefore needs to be kept clean. Under these conditions pumps can last up to 10 years.
- Solar panels and mounting structure: Solar panels and their mounting structure generally require very little maintenance since there are no moving parts. Panels need to be kept clean and free of shade however, while the mounting structures should be stable. The PV array should be protected from animals and falling objects. Well cared for solar panels and mounting structures last up to 20 years.
- Electronics and controls: As controllers/inverters are sensitive to overheating, they have to be installed in a place where faultless operation is guaranteed. Factors to be considered include the ambient temperature, the heat dissipation capability (ventilation) and the relative humidity. For service and maintenance purposes, the controller should be easily accessible. Furthermore, there has to be a circuit breaker between the PV generator and the controller. Insects and small animals, such as lizards, like to build their nests in junction boxes and may destroy electronic components (e.g. by formic acid). Proper sealing of all openings (e.g. with cable glands) is essential.
- Irrigation System: If drip irrigation is applied, the water must be filtered because the drip emitters can clog easily. Depending on the sediment load of the water, the filters must be cleaned regularly – this can be up to several times a day. This requires a certain level of technical knowledge and skills. In addition, the drip lines must be flushed regularly and the drip elements must be examined for blockages and replaced if necessary. The SPIS tool MAINTAIN – Water Application Uniformity Guide is applied to check the uniformity of water distribution in a drip irrigation system. The test is part of the system acceptance (see module SET UP) but is also part of a routine check. It should also be considered that for hard water (irrigation water with high dissolved lime concentrations), scaling up and clogging of pipes will occur if pipes are exposed to heat (direct sunshine).
On the next page an overview of common failures from the field and the associated fixes are given.
Example of Common Installation Mistakes
Example of a dangerous cable connection
Although the installer already used rubber tape to insulate the wires, the cable connection is exposed on the ground. Electrical safety is questionable, particularly during irrigation or strong rains.
Galvanic corrosion of a manual tracking system
Over time, metal objects are subject to rust and corrosion. Corrosion is normally associated with non-precious metals such as steel, zinc and aluminum. In the presence of air, water or salt, these metals will corrode rapidly and need to be covered with a protective sealant.
Limited heat dissipation capability of corroded controller housing
The metal housing of the pump controller is extensively corroded. Furthermore, the housing has no natural ventilation and after closing its front door, overheating of the controller may happen.
Examples of Inadequate Maintenance
Accumulated grime at the lower end of a PV panel
Even though only a small part of the panel is covered in grime it has a big negative impact on the efficiency of the panel. It can be easily removed through scrubbing with a cloth covered sponge or soft brush with clean water.
Example of shadowing by not maintained ground vegetation
Solar panels produce less power when they are shaded and should be placed where there is no risk of shadows on them. A shadow falling on a small part of a panel can have a surprisingly large effect on output because the cells within a panel are normally all wired in series, the shaded cells will affect the current flow of the entire panel!
Example of a dangerous cable connection; Galvanic corrosion of a manual tracking system; Limited heat dissipation capability of corroded controller housing; Examples of inadequate maintenance Accumulated grime at the lower end of a PV panel; Example of PV shadowing by not maintained ground vegetation. (Source: Andreas Hahn, 2015)
- Instructions on proper maintenance of each component of the SPIS;
- Checklist on water analysis.
- Producers / producer groups;
- Agricultural advisors;
- Technology and service providers (electricians, companies providing PV systems).
- Regular maintenance is indispensable for efficient and long term operation of any pumping and irrigation system.
- An SPIS is reliable and maintenance costs are low if maintained adequately.
- Maintenance plans should be reviewed regularly together with the technology/service provider and the agricultural advisor.