The Hidden Cost of Deferred PV Maintenance

A White paper by Wayne Williford V.P. O&M Stellar Energy

 

The commercial PV industry has seen tremendous growth in past decade. The need for professional and experienced operations and maintenance service providers has grown right along with it. Initially, commercial PV owners and managers were not as concerned with availability and rapid return to service times as they are today. With rebates, energy output guarantee’s and a large number of systems now being installed as power purchase agreements, the requirement to maintain and optimize is in every contract and in every PV system manager’s mind.

 

The Risk: PV systems that do not have scheduled maintenance programs to support the product and power production do not typically have the best ROI for the customer. These systems often under perform from “soon after commissioning” until a continuous maintenance plan is in place and operational.

 

The Hidden Cost: The largest hidden cost is failed power production expectations.

Customers plan, forecast and budget based on the expected power that is estimated during design and construction. APV developer’s future financing can be seriously affected by an underperforming project. Expensive material repair costs, additional resources to manage and repair the asset can add up quickly. Damage to the builder’s and the solar industries reputation to provide a cost efficient energy alternative is also very costly.

 

The Problems: PV equipment needs regular maintenance to not only maintain functionality, but also to maintain manufacturer warranties.  At some point, a common misconception of unknown origin was developed, claiming that solar was synonymous with an ethereal creature, where you can “get it and forget it”.  The hard truth is solar equipment is comprised of manufactured articles; raw-earth materials mixed and manipulated in a production facility to become a pre-engineered element.  Therefore, any component of the system has potential for failure,

and every component left uncared for will deteriorate and fail over time. The key to proper maintenance is planning when, and how much service should be done, so the original value and functionality is maintained without incurring more than “reasonable cost”.  Finding and contracting with a reputable and experienced PV O&M service provider can be time consuming and challenging. Knowing how much service to contract for and at what price can be a difficult process to work through unless you find an experienced and qualified service partner.

 

Inverter: The inverter is the core of any PV system.  Our networking system of an AC electrical grid requires the inverter to translate DC sine waves produced by the modules 

into a usable AC format.  This process requires many electro-mechanical components that generate large amounts of heat.  Cooling and recirculation fans are installed inside the inverter housing box as a means of climate control. The cooling fans draw in cooler outside air while the recirculation fans eliminate an overabundance of humidity.

The majority of inverters are installed outside, in relative space to the array field.  Although designed to handle the elements, water, dirt, and debris intrusion is an issue.  Moisture can be drawn in by the cooling fans or introduced by sprayed irrigation.  Dirt and other debris can be absorbed by the cooling fans’ vacuum.  Filters are in place to reduce the amount of influx, however they are not foolproof and the filters do require regular cleaning. Manufacturers typically require an annual preventative cleaning of filters to maintain warranty status.  The filters can also get clogged with the intake debris, lowering the effectiveness of the cooling fans, allowing the inverter to overheat, and ultimately forcing the inverter into an automatic shut down.

 

Ground faults:-failed grounding lugs, conductor insulation failure, and pinched or loose conductors can cause system downtime, under performance or damage. Racking: Loose or missing fasteners, improperly installed hardware and corrosion can lead to module, system and or property damage. Module failure: Underperforming and failed PV modules can cause a number of issues that affect system performance. If undetected during system commissioning and left in a string of otherwise healthy modules, string and subsequently array production can and will be reduced. Conduit failure: Exposed conductors from damaged, failing or broken conductors can lead to some very expensive and time consuming repairs. Troubleshooting faults, pulling new conductors, splicing testing, and terminating wiring is a road no system owner or manager wants to travel. This problem can lead to other future failures when undetected and not repaired.

Performance monitoring (DAS) - Performance monitoring is a solar array’s lifeline to its service provider.  Email notifications alert a monitoring specialist to irregularities on site, such as low production or a down inverter, issues that could otherwise go days or weeks without being noticed.  Data collected from monitoring also allows easy performance reporting to stakeholders and rebate programs.

 

Module cleaning: Properly cleaned modules can increase production by 25%, depending upon environmental conditions and type of soil.  Cleaning also provides an opportunity for each module to be visually inspected for any cracks, impact points, or hardware malfunctions.

 

Corrosion: Stuck and or failed fasteners on the system can disable mechanical functions, affecting structural integrity, and aesthetic quality.

 

Landscaping - Landscaping also plays a role in the effectiveness of a PV system.  Untended grounds can generate shading on panels, lowering production values.  It is also not uncommon for weed abatement procedures using large mechanical equipment to throw up dirt and rocks, damaging panels at the cost of the owner.

 

Security-Vandalism and theft can seriously impact a PV systems availability. Security is a sizeable investment in most cases, and the maintenance of these systems is critical to 

the ROI of the project. A security system that is purchased and installed and then left un maintained is a complete waste of money. Inspection, Calibration, Cleaning and software updates are vital to the continued effective operation of most security systems.

                                            

   

 

 

The Plan: Preventative vs.  Reactive Maintenance It’s important to remember that not all sites are designed or constructed the same nor are they located in common environments.  One of the most important, and commonly missed, preventative maintenance services is inverter filter cleaning.  Just as dirty panels produce significantly less than clean panels; dirty inverter filters reduce the inverters efficiency, and can ultimately suffocate the inverter.

A well scoped and scheduled maintenance plan is essential to the customers ROI.

This maintenance plan should be customized to the system that it is being used to maintain and not a generic form that is good for every system in the “fleet”

 

The schedule:  Preventative maintenance should be performed at least once a year.  However, each site’s characteristics will vary.  An agricultural packaging facility may need service four or more times a year, whereas a college campus may only require an annual visit.  It is important to seek a provider who is capable of developing a maintenance package to suite each individual system’s needs. Data Acquisition Systems can provide a suite of useful information that show the service provider what and when essential maintenance services are needed. The optimum time to clean solar modules or set a tracker program can be determined through DAS as well as replacement of system fuses and modules.

 

The documentation:  Reputable service providers will be able to supply maintenance reports upon completion of any maintenance service. This documentation is vital to the effective maintenance of the system. It details the scope, schedule and service history that is unique to the system. This documentation can and will save the manager/owner time and money in the short and long run of the power systems service life.

This may require more involvement on the owner/managers side, but allows greater scrutiny and protection of your investment. 

 

The payback:  Regular maintenance could mean the difference between a 6 year high production lifespan or a 20 year-plus, high production lifespan, and ultimately a corresponding ROI.  Reactionary services on a PV system tend to be costly, and full unit replacements may be necessary to return the system to operation. Systems that operate at 99% availability for the production year typically earn a high ROI and increased customer and industry confidence.

 

 

About Stellar Energy

Stellar Energy is a large-scale full service solar O&M service provider with complete project development, design, engineering, procurement, and construction (EPC) management 

capabilities. The company also provides professional operations and maintenance services for solar power plants as well as small business and residences. With installations spanning government, education, commercial, and municipal customers. For information about professional O&M services for your PV system, contactStellar Energy by phone at (707) 347- 9938 or online at www.stellarenergy.com or email: wayne.williford@stellarenergy.com