Storing Up Panel Problems
This article was originally published in pv magazine - March 2025 Edition.
Clean Energy Associates (CEA) is receiving more calls from solar developers concerned about warehouse panel damage. CEA’s Senior Engineering Manager Claire Kearns McCoy explains how improper handling, stacking, and storage conditions can lead to long-term issues.
Moving solar panels exposes them to damage, and panels frequently moved in a warehouse face greater risk.
Solar developers typically experience warehouse-stored modules in one of two ways: They either buy them from warehouse storage or store products themselves, perhaps after buying in advance and experiencing project delays.
Thorough warehouse inspections during storage and before transfer to project sites are vital. Buyers should evaluate module quality, storage conditions, and inventory accuracy.
Inspection steps
Visual inspection can identify external damage, assess packaging conditions, and ensure modules are stored according to manufacturer guidelines. Mishandling, indicated by broken pallets, crushed corners, or torn wrapping, can be spotted.
Pallet and storage condition evaluations involve checking climate control, humidity levels, stacking arrangements, and other factors to verify modules are stored in a safe, controlled environment.
Electroluminescence (EL) testing can be conducted on a sample of the modules for a more detailed assessment. This testing method is paired with a detailed visual inspection of the modules and helps identify defects or damage in the panels that may not be immediately apparent.
This is especially important for modules purchased from warehouse storage that have an unknown manufacturing quality, as this inspection provides an opportunity to identify manufacturing defects, in addition to shipping and handling damage. EL testing is also important to identify microcracks since these can negatively affect panel performance over time, and end up compromising module integrity.
Inventory verification is another critical aspect of warehouse inspections, particularly for developers using warehouse storage to meet “safe harbor” tax requirements, which would protect them against tax penalties. Inventory verification confirms that all expected pallets are present and serial numbers match supplier records. Verifying inventory accuracy helps developers maintain proper documentation and ensures that no modules have been misplaced or swapped during storage.
In-person verification
Panel packaging can withstand short-term transit and handling, but is not designed for exposure to the elements.
Warehouse operators may provide developers with information about storage conditions, but it is not always accurate. Some developers have been told their modules were stored in climate-controlled conditions, according to manufacturer guidelines, only for inspectors to find them in an unregulated space exposed to high humidity or extreme temperatures, or improperly stacked.
Regular in-person inspections ensure that modules are stored as promised and enable developers to address issues before shipping panels to a project site. Modules that have remained untouched in a warehouse are generally at lower risk than those frequently moved. In some cases, warehouse staff may shift modules to make room for new inventory, exposing them to potential damage.
If modules are repeatedly moved using forklifts, or repositioned in ways that do not follow stacking guidelines, their structural integrity might be compromised. Developers storing modules for extended periods should schedule periodic inspections – typically every six months to a year – to ensure their inventory remains in good condition, whether or not it has been disturbed in the meantime.
Finally, supervising the container loading process to ship modules from a warehouse to the job site can catch additional problems. At one recent project, CEA observed the loading process at a warehouse and was surprised to see a different loading procedure used for each container – none of them matched the manufacturer’s guidelines.
When modules are improperly loaded into a shipping container or truck, they are subject to damage due to the vibrations caused in the transportation process and can even shift in a truck if not properly secured.
Outdoor storage
Some consider storing modules outdoors as a cost-saving measure but this is highly discouraged. While panel packaging is designed to withstand short-term transit and handling, it is not meant for longterm exposure to the elements.
One of the biggest risks from outdoor storage is moisture exposure. Humidity, rain, or condensation can seep into packaging, leading to corrosion and water damage. Uncapped PV connectors are especially vulnerable. Prolonged sun exposure can weaken packaging materials, making modules more vulnerable to contamination or breakage.
In some cases, unprotected storage areas may attract rodents or insects that can nest in packaging and cause additional damage. Many manufacturers explicitly prohibit outdoor storage. Failure to follow such guidelines could void warranties.
“Unprotected storage areas may attract rodents or insects”
Contractual protections
When purchasing warehouse-stored panels, developers should ensure that agreements explicitly outline their rights to inspect and report defects. The contract should specify a clear time frame when buyers can conduct inspections and document any issues before taking possession of the modules.
Liability during storage must also be clearly defined. Developers should confirm whether they or the warehouse operator bear responsibility for damage that occurs while the modules are in storage. Ownership terms should be carefully reviewed to avoid ambiguity.
Contracts should also address proper loading and transport procedures to minimize the risk of damage when modules are shipped from a warehouse to a project site. The agreement should require warehouse operators to follow manufacturer guidelines for container loading, including stacking configurations, securing pallets with straps, and placing airbags or other protective materials in the correct positions.
Ensuring that these standards are contractually enforced can prevent unnecessary damage during transportation. Contracts should also specify who bears financial responsibility for unforeseen damage, such as a warehouse fire or structural failure. Developers should confirm their supplier or warehouse provider carries appropriate insurance coverage to protect inventory.
Claire Kearns-McCoy is Senior Engineering Manager at CEA. She has extensive experience with module field inspections and analysis of EL imaging tests.
