Monday, August 3, 2015

Solar Farm Operations and Maintenance Issues

For the operation of commercial and utility scale PV power plants, a critical solar industry sector that needs particular attention is operations and maintenance, usually referred to simply as O&M. The performance, and ultimate profitability of a solar installation depend upon the competence and experience of the O&M team.
What Should Be Done
Through a proactive preventative maintenance plan, the O&M team keep tabs on potential issues and are sometimes able to stem off major failures by making smaller repairs keeping a solar installation in good working order.
While it is impossible to prevent all potential failures or damages that can occur on a solar farm, should a solar monitoring system set off an alarm indicating an outage, the response time of the O&M team can impact power generation if failures, damage or other issues are not addressed in a timely manner. As important as a preventative maintenance plan, a well-developed corrective maintenance plan can reduce costly downtime.
Any time a string or entire array is offline or experiencing periods of underperformance due to an O&M issue basically results in energy loss – or to be blunt, money going down the drain.
Performing Comprehensive Inspections
As part of a preventative maintenance plan, consistently identifying and documenting areas of improvement and correction helps uphold system integrity. Checklists for inspections are used to assure potential issues aren’t overlooked including environmental factors, equipment and other general issues. Here are some of the items that are regularly inspected and managed:
O&M Environmental Inspection
Vegetation Abatement
Vegetation growth under a solar array can range from a slight nuisance to a major issue very quickly. Vegetation can shade cells, interfere with wiring and affect structural integrity. Additionally, wildlife may be attracted to nest, graze or burrow into vegetation causing added potential concerns for system integrity.
Panel Shading
Trees and other obstructions should be cleared during the planning and construction phase of a solar installation; however, not all solar power plant plans are created equally. Therefore, landscape should be accessed regularly and trees that are causing shading should be removed to optimize power output.
PV electrical output is very sensitive to shade. Shaded cells absorb power instead of adding to the power produced by a solar panel. A shaded cell has a much greater reverse voltage compared to the forward voltage of an illuminated one, it can absorb the power of many cells in the string and the output will fall drastically.
Natural Damage 
A hurricane or hailstorm can destroy the solar panels and equipment on an array. Damaged panels, or wind torn racking and other equipment can severely decrease output or completely take a system offline. Keeping a watchful eye on changing weather conditions and inspecting the equipment following a storm is necessary for the overall health of the solar farm.
Ground Erosion
Sudden soil and ground erosion caused by water and wind can have an adverse effect on a PV plant. Loss of topsoil can cause racking to shift affecting the ability of panels to generate the energy. As racking moves, panels are moved from their optimal positioning and energy generation suffers. Erosion can also lead to flooding and destruction of equipment. Proper and frequent site inspections will alert the O&M team to any erosion that could put operations at risk.
Dirty Panels
Pollen, dust, snow, leaf fragments, and bird droppings can absorb sunlight on the surface of a panel, reducing the light that reaches the cells. Solar panel cleaning helps increase performance over the lifespan of the equipment. Routine cleaning should be a part of all O&M plans.
Animal Abatement
Care should be taken to keep any wildlife out of a solar farm. During an inspection, technicians will look for any signs of animals burrowing under fences, holes in fencing, or even animal droppings on the ground around panels. Once inside the perimeter fence, equipment can be destroyed, wires chewed, holes dug causing racking to shift and countless other destructive behaviors have been recorded as a result of wildlife breaching a solar installation’s perimeter.
O&M Equipment Inspection
Shorted Cells
Production defects in semiconducting material often go undetected before PV cells are put into solar panel assemblies. Shorted cells can impact the productivity of a panel if not addressed in a timely fashion. Infrared imaging is used to identify these defects. This type of testing is efficient and cost-effective to test and measure a cell’s performance and its electronic structure help ensure maximum energy production.
Cell Browning/Discoloring
Aging panel cells will turn brown and discolor from the UV radiation exposure. This degradation in the film leads to impaired output and productivity. During inspections, cells will be visually inspected on a regular basis.
Defective Trackers
Solar trackers can increase total power produced by about 20-25% for a single axis tracker and about 30% or more for a dual axis tracker. Defective trackers can contribute significantly to lowered performance output and should be serviced as soon as detected.
Transformer Leaks
Preventative maintenance inspections to certify that transformers are in good condition help avoid transformer leakage. Transformer leaks can cause land contamination and other safety risks. There several ways to carry out preventive maintenance in transformers; however, monitoring transformer oil temperature, pressure and level to prevent a transformer from leaking in the first place is the best way to avoid down time issues.
Inverter Damage 
Inverters are core components of grid-connected solar energy systems converting low voltage, high current signals from PV panels into voltage that is compatible with the utility grid. Regular inspection and monitoring of inverters is very important, since changes to voltage and frequency may occur that affect performance as well as the safety of those in proximity. Eighty percent of PV system downtime, including partial string outages or complete outages, is the result of inverter failures.
Broken Conduit
Ground movement, vegetation growth, and animal activity can all lead to broken conduit. Regularly measuring isolation on cables ensures underground runs are damage free. This is an important part of any regular preventative maintenance inspection as broken conduits can cause cable breakage or damage, leading to personal and property hazards such as shock and fire.
Combiner Box Damage
With the ability to simplify wiring, combiner boxes combine inputs from multiple strings of solar panels into one output circuit. Normally 4 to 12 strings are connected to a combiner box. If damaged, they pose a safety risk as well as a major decrease in productivity.
O&M Additional Inspection Items
Vandalism Damage
Vandals pose a major threat to the operation of a solar farm and attending to the business at hand – the generation of energy. Destructive behaviors such as panel and other equipment damage as well as theft can occur. Maintaining perimeter fencing and enlisting security, if vandalism becomes a major issue, is key to maintaining operations.
Perimeter Fence Damage 
In addition to deterring vandals from entering a solar installation, perimeter fencing keeps unauthorized personnel and animals away from the solar array and the potential risks of coming in contact with high voltage equipment. Signs of animal activity or other type of perimeter breach during a regular inspection requires quick response for repair to avoid future infringement.
Miller Bros. Solar (MBS) is a chosen leader in operations and maintenance (O&M) solutions due to the company’s project expertise, full construction capabilities, and 160+ pieces of heavy equipment. MBS is one of the few electrical contractors that can simultaneously self-perform multiple utility scale solar projects while exceeding client expectations, controlling costs and adhering to timelines and customer schedules.
Miller Bros. Solar provides O&M services for solar projects in the following states: Connecticut, Delaware, Ohio, Georgia, Indiana, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Vermont, Virginia, and West Virginia.
For more information, visit or call 610-832-1000.

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