Our routine inspections and maintenance plans will ensure your system is operating safely, the life of your equipment is extended, generation is increased, and the return on investment is maximized.

Torque is a commonly used term in Solar PV system inspection, which refers to the act of tightening a mechanical fastener. The fastener can cover a wide array of details, not limited to attaching structural members, electrical connection and weather tight seals on conduit and enclosures.

Why is This Important for Owners and Financiers?

Under torqued fasteners are a common root cause for catastrophic electrical and mechanical failures and are one of the easiest issues to prevent. Diligence during construction and O&M activities can eliminate this issue entirely.

Image 1: Mechanical Lug
Image 2: Compression Lug
Image 3: Structural Bolt
Image 4: Failed Torque Demonstration (hot spot due to poor torque)

How Hardware Fails

There are two failure categories for torqueing:

Over torque – where the recorded tightening exceeds the specification, this can lead to:

  • Galled hardware, where the bolt/nut weld together. This requires the bolt to broken in order to remove.
  • Stressed hardware, where the material limits are approached, and leads to premature failure.
  • Deformation, where the bolted connection becomes crushed and damaged.

Under torque – where the recorded tightening falls below the specification, this can lead to:

  • Hardware can come apart under environmental stresses (like wind and snow)
  • Electrical connections can become hot, and lead to arcing or fires.

How to Set Up for Success

A few key takeaways to note:

Step 1 – Documentation and Planning for Construction

Success starts with the documentation and tools during construction. We look for:

  • All torque values clearly identified in the respective drawing sets or installation manuals for each task and fastener type.
  • All tools used should be properly matched and calibrated to the specific task.
  • Avoid battery powered tools unless they have an under-torque lockout, to prevent under-torque due to low tool battery voltages.

Step 2 – Maintain Diligence During Construction QC Inspections

Proper quality control methods are integral with the construction.

  • Mark all tested connections as they are tested to reduce the gap between the inspection and the work performed.
  • Mark mechanical connections with a UV rated paint marker. This ensures the QC marks will be visible for years.
  • Mark electrical connections with a QC gel. This ensures any tampering will be visually notable and should trigger a reapplication of the connections.
  • Maintain test records, with clearly identified target limits and pass/fail notes with photos when failures occur.

Step 3 – Long Term Inspection and Maintenance

The final step is confirming the long-term health of the system. What we look for:

  • Use of Infra-Red (IR) thermal scans to ensure hotspots don’t creep up over time.
  • Visual inspections for signs of wear and tear or corrosion on mechanical fasteners.

What are the biggest critical to quality pitfalls related to torque?

Eliminate re-torque from the maintenance vocabulary for electrical connections. Torquing should be considered a one-time event. Better to use IR scans to identify under-torqued hardware that needs re-torquing.

Who Can Ensure Torquing is Done Correctly?

PV Pros has a Field Service department that specializes in QC inspections, reference commissioning, and preventive maintenance. We offer annual monitoring and reporting as part of our service offering.

To save time and money on your next PM, reach out to PV Pros at info@PVpros.com.

By the end of 2019, Verizon will obsolete its coverage on legacy 3G networks. ATT will follow suit by 2021. The time to implement a replacement plan is now.

Why is this important for owners and financiers?

Connectivity to a site is the lifeline for asset managers and owners. This allows for performance monitoring, but more importantly, meeting any net meeting and reporting obligations every month from the utilities. Lapses in connectivity would impact revenue billing.

Also, spring time PM is underway. Combining the 3G updates during this time minimizes truck rolls and saves on cost.

Next Steps for avoiding loss of coverage?

Planned maintenance involves a few key tasks:

Step 1 – Confirm what’s in place

PV Pros will review the critical components in the networking hardware

  • Confirm if 3G is being utilized
  • Confirm the carrier and the risk of hitting the end date as published by the carriers

Step 2 – Make the switch

Not all hardware is created equal. PV pros will:

  • Replace the cellular equipment with ruggedized outdoor rated replacements
  • Confirm connectivity with your DAS provider and provide a clean bill of health to the system

What should happen leading up to the PM

PV Pros will be reaching out to all customers abut their projects and next steps on replacement.

Our proactive approach will insure a smooth transition into the next generation of cellular technology.

For any support on your system, reach out to PV pros at info@PVpros.com.

Spring cleaning also applies to solar! After harsh exposure to winter’s snow, ice, and rain, systems benefit from routine inspection and maintenance. This ensures performance will be optimal as the season progresses.

Why is this important for owners and financiers?

The solar peak generation season is April through September. Unplanned outages in this season costs the owner more in lost revenue.

Typical ground mount system seasonal performance in the North East US:

What gets done during a PM?

Planned maintenance involves a few key tasks:

Step 1 – Visual Inspection and Repair

Weather, landscaping, insects, dirt and debris can all contribute to equipment degradation, which can lead to full breakdown. We look for:

  • Wire management integrity. Broken wires lead to arc faults and stoppages or worse…fires.
  • Inspect structural components for lose hardware and signs of corrosion.
  • Filter cleaning for inverters or any ventilated equipment. This prevents overheating and derated performance in the upcoming summer months.
  • Removal of pest and vermin nests and debris buildup from modules, racking and equipment enclosures. When found inside enclosures, sealing the ingress point to prevent future intrusion.
  • Ensure all meteorological instrumentation are mechanically sound, clean and oriented as expected.

Step 2 – Diagnostic Inspection and Repair

Some issues require a more in-depth inspection utilizing specialized tools:

  • Infra-Red (IR) scans of all major electrical terminations. This insures proper continuity and eliminates overheating.
  • Aerial (IR) scans of the solar array. This is the fastest and most thorough way to spot both hotspots and cold spots, allowing for follow up repairs.
  • IV curve traces. Where (IR) scans can only identify a problem, IV curve tracers allow for root cause identification.

Step 3 – Performance Testing

The final and most important step is confirming the operation of the system performance. What we look for:

  • Data acquisition system (DAS) reporting as expected.
  • Review of the annual performance for deficiencies in the expected performance. A performance ratio or regression test can help determine if the plant is meeting its performance capabilities.

What should happen leading up to the PM?

Ideally, the system should be monitored throughout the year, to ensure issues that arise are dealt with in a timely fashion. Monthly performance reporting is also an effective tool to ensure the system is performing as expected.

However, for certain issues, it may be more cost effective to push repairs to the PM interval. This reduces repair costs by minimizing truck rolls.

Who conducts preventive maintenance?

PV Pros has a Field Service department that specializes in the annual preventive maintenance (PM) and other maintenance needs. We offer annual monitoring and reporting as part of our service offer.

To save time and money on your next PM, reach out to PV Pros at info@PVpros.com.

Even when systems are installed with top notch workmanship and thorough inspections by third party commissioning agents such as PV Pros, it doesn’t ensure the system will stay that way year in and year out.  Mother Nature puts a lot of wear and tear on your systems.

Here are examples of issues that were not present during installation or commissioning but popped up in the subsequent year(s) of operation. This is why annual and semi-annual preventive maintenance is so important.

Soiling – Dust, dirt, leaves, bird droppings… the lower the tilt or drier the climate the worse it gets.

Animals Nesting – This is a major fire hazard. You don’t want animals creating nests, chewing through wiring, and igniting the leaves and dry materials.

Ballast Degradation – In early years of solar, not everyone was wise to the need to use blocks that meet ASTM C1491 and will hold up against moisture and freeze-thaw cycles.  We still see some systems being installed today without proper concrete ballast blocks.  You may not realize inferior block was slipped in until you see this:

Conduit Separation – Summer’s heat and winter’s cold causes expansion and contraction that pulls apart connections. Separated conduits then lead to water infiltration as shown in the following photo.

Water Infiltration – Connections may appear tight during installation, but sometimes work their way loose and let water into enclosures.  Even if its not pouring out of an enclosure, just a little condensation is enough for internal components to rust and corrode, significantly shortening its lifespan.

Vegetation – This isn’t just an aesthetics issue, the plants are blocking the air flow around the equipment causing it to run hotter and shorten its lifespan.  Vegetation around the array doesn’t just cause shading losses, the pollen creates additional soiling losses.

Thermal Failure – Imminent failure often isn’t visible with the naked eye. But taking thermal IR images of the equipment and connections will show something running hot, indicating a malfunctioning device (such as the circuit breaker in this picture).  IR imaging lets us locate issues and fix them before it results in extended downtime.

Standing Water – Clogged drains cause water to build up.  Racking and components are designed to be rained on, but not be submerged for extended periods of time.  Clogged drains shorten the life of components, and in the winter don’t allow the snow to melt.

Thermal (IR) cameras are a great tool for preventative maintenance and inspection of your PV system. With a little thermography “know-how” and some image focusing, problems can be discovered quickly before they create a fault or safety hazard in the PV system. Below are issues that can lead to a system fault that the infrared camera can expose:

  • Hot spots near lugs from poor wire terminations and untorqued lugs.
  • Hot spots on modules- indicating damaged cells.
  • Excess heat on feeders created by unbalanced loads

No two sites are alike; therefore, we must calibrate our camera to site specific conditions. Below are two important settings that are often overlooked when using an infrared camera.

Emissivity
Emissivity is how well an object reflects radiation. Very reflective surfaces such as shiny metals have low emissivity. Absorbent surfaces such as rubber and electrical tape have a high emissivity value. Knowing this, the infrared camera will have to be calibrated when measuring bus bars and recalibrated when measuring insulated cable. Unfortunately, frequent recalibration is time consuming but very necessary to obtain accurate measurements. So how do we adjust and maintain two objects with different emissivity properties in one image- like a shiny aluminum mechanical lug and the XHHW jacketed feeder? You could take two different images with respective emissivity settings for each item or you could exploit your knowledge on emissivity and keep both items in one image. I will describe the procedure below, but first, it should be made known that this procedure incorporates contact with mechanical lugs and only qualified persons with de-energizing and system testing training should be performing this procedure:

  • Wire insulation has emissivity values of 0.95- equivalent to black electrical tape. Set the infrared camera emissivity level to 0.95 and apply black electrical tape onto the lug. Give the tape a few seconds to adjust to the temperature of the lug. This “surface” will now reflect both the temperature of the lug and also possess the emissivity properties of the wire insulation. Without the tape, the shiny surface would have registered much lower temperatures (due to low emissivity) and presented false results.
  • Safety first! Do not apply tape to any exposed components while the system is energized! Even though the system is off, always be mindful of line and load sides!
  • Here is a link of various materials and their respective emissivity levels, courtesy of Fluke. http://www.emlab.com/m/store/Fluke%20Thermal%20Camera%20Emissivity%20Values.pdf
    If you are using a model by Fluke or Flir, it’s likely the emissivity values are already programmed into the camera and you just have to select the proper one.

Background Temperature
Think of “background temperature” as “reflected temperature.” It is the infrared energy of our surroundings that is being reflected off the object that we are trying to measure. A real world example: Have you ever seen your IR reflection in the image? I tend to see this occur when capturing bus bar images in switchgear or panelboards. It also tends to be more dramatic on colder days when your body heat is much higher relative to the surface temperature of the measured object. This can cause false alarm when looking over the captured image as the alleged “hot spot,” which in actuality is a portion of your reflected body heat, is being registered by the camera lens. Be mindful of this concept. If you see a hot spot on your display, see if simply changing your position will fix this anomaly. If you find yourself in a small or cramped room and hot/cold background objects cannot be avoided from the image, you will have to calibrate your camera and use a curtain. The simplest way is to scan the room and note the average temperature. Adjust for this value in the background temperature settings. Then, place a “curtain” (I use a sheet of cardboard) between the background images and the camera- basically, right behind you. This will prevent any background heat from being reflected off the measured image and reaching the lens.