Weeks before commissioning, the solar asset owner seeks thermal study from EPC

With the hot-commissioning deadline fast approaching, an EPC in charge of constructing one of the largest solar farms in the state of Alabama, faced a major hurdle. The asset owner wants a thermal study of the asset as part of the punchlist activity prior to commissioning. The EPC needs a quick and easy solution to both identify major PV and electrical defects and remediate thermal issues. Delays, if any, will prove very costly considering the cliff dates and liquidated damages built into the EPC contract.

Since the EPC has used the SenseHawk Solar Digitization Platform (SDP) for several activities during construction at the site, including earth moving and construction monitoring, it explores using the SDP to tackle the problem. The digital twin of the asset, created using SenseHawk’s proprietary asset information model (AIM), is already available on the platform. The digital model incorporates all information from the site with respect to the components, inverter-combiner box-string labels, and all logical and hierarachical interconnections.

While aerial thermography studies conducted by O&M teams post-commissioning (6-12 months into the life of the asset) were common 5 years ago, pre-commissioning studies are starting to become de-rigueur. Asset owners are realizing the benefit of catching thermal and electrical failures early, right after construction is completed.

Further, OEMs are recognizing the validity of these studies in processing warranty claims, subject, of course, to rigorous on-field analysis. Aerial thermography reports only reveal a symptom. The root cause (which ultimately determines the validity of a warranty claim) needs to be ascertained on the field through visual inspection for damage or IV curve tracing on defective modules.

Most providers that perform aerial thermography deliver simple PDF or CSV reports of thermal defects. The translation of these reports into the action required on the field is a laborious process involving printouts, guesswork regarding the defect location, and a lot of heartburn.

Figure 1: The digital twin of the solar power created on the SenseHawk SDP at the start of construction

The EPC has also completed an important activity that will prove to be particularly useful for warranty claims. During the final stages of construction, serial numbers of every installed module had been captured and saved onto the digital twin on the SDP using the BUILD feature.

Figure 2: Module serial numbers captured for all installed PV modules using the Scan capability of the BUILD feature

SenseHawk is uniquely positioned to address the EPC’s problem

The EPC has three weeks to identify, classify and remediate PV and electrical defects, on a 130 MW site. Using OBSERVE, the first two steps (identify and classify) are completed in one week.

SenseHawk’s pilots complete drone data collection and image uploads to the platform within four days. The thermography reports are available on the platform within the next three days and indicate over 5000 defects of various types, spread out over 900 acres. The EPC still has two weeks to fix these issues and close out the punch list.

Figure 3: Over 3500 defects identified and classified on the map view of the powerplant on the SDP

The SDP has productivity tools designed for management of tasks and workflows on the field. Using the WORK and COLLAB features the EPC is able to drastically reduce the time taken for defect remediation. Each recorded defect results in the creation of a related task that is then assigned to field teams that can use the GO mobile app to view tasks and detailed checklists, have contextual chats, and create status updates along with attachments.

Figure 4: Tasks, automatically created for each identified defect, can be assigned to the field team

Figure 5: Checklists and attachments can be added to each defect related task to help guide field personnel in remediation

Each task contains the defect type, string number, and temperature delta of the hotspot. The Project Manager is able to attach custom checklists to the tasks, one for each defect type. Defects will be automatically classified by severity; string related issues to be tackled first, followed by module-related, and finally cell-related issues. Multiple field teams are created and defects are assigned to each of them to enable quick investigation on the field. The tasks will show up on the mobile devices allowing users to easily navigate to the exact locations of defects using their mobile GPS.

Figure 6: Field users can navigate to the exact defect location using the mobile application

Technicians spread out to individual defects and conduct investigations based on the task list. A large number of defects are found to be caused by cracked modules – caused by a bad batch from the PV supplier. Photographs of the damaged modules are attached to the associated task on the app.

Figure 7: Field investigation reveals broken glass on the module – a manufacturing defect – and so photographs are attached to the associated task

Another large set of modules has abnormally hot cells probably caused by a manufacturing defect. These defects are verified on the field through IV curve tracing, and screenshots of the IV trace are added to the task associated with the defect. The EPC is able to then export the results of the on-field defect investigation into excel sheets, complete with hyperlinks to the tasks’ attachments.

Figure 8: Results of the field investigation summarized in Excel for easy reporting to the Owner and to the OEM for warranty claims

The excel clearly indicates the resolution status of each defect – some are resolved on the field, while many (over 3500) are liable for warranty claims. The photos and other attachments made to each defect related task provides a quick and effortless way to verify this. The EPC submits the excel file to the owner, who is satisfied that the defects are either already rectified or will be rectified through warranty claims and clears this item from the EPC’s punch list. This is all done within 10 days of the thermal reports being made available to the EPC—well within the commissioning deadline.

Post-commissioning, the actual task of warranty claims remains. The serial numbers that were meticulously cataloged prior to the thermal scan using BUILD, prove to be especially useful. Each defect haS the corresponding module serial number associated with it. The owner is able to simply send a list of defective serial numbers to the OEM, who is able to quickly verify the claims using evidence already gathered during the on-field investigation.

Figure 9: Module serial numbers available for each tracker row make the warranty claims process seamless with the supplier

In this manner, a seemingly gargantuan task is completed in less than three weeks with the help of the SenseHawk SDP’s OBSERVE feature. The powerplant operates at maximum efficiency from day one, and the usually complicated task of warranty claims is reduced to a simple checklist activity.

To know how the SenseHawk SDP can help you design and build your project better, book a demo at www.sensehawk.com/request-a-demo/