Galvanic Corrosion in Solar Mounting Fasteners: RFQ Guide
Plan solar mounting fastener enquiries around material contacts, site exposure and bonding requirements. Use this checklist to prepare a clearer RFQ.
Galvanic corrosion is an assembly issue, not simply a fastener grade issue. Assess the contacting metals, electrical continuity and wet exposure together. For solar mounting enquiries, pair the released fastener drawing with the mating materials, site conditions and approved bonding design before selecting a proposed material or finish.
Understand the metal contact before specifying the fastener
ASSDA identifies three necessary conditions for galvanic attack: a conductive liquid, electrical contact between the metals and a sufficient difference in their potentials. In a susceptible couple, the more active material is preferentially attacked. A stainless steel screw can therefore remain visually sound while the adjacent aluminum is affected.
Start the enquiry with an interface description. Mark the fastener head, washer, clamp, rail and receiving thread on an assembly sketch. This is our recommended purchasing workflow: it helps a supplier see which contacts require engineering review instead of guessing from a standalone screw drawing.
- Identify each mating material and its specified surface condition.
- Include an assembly drawing revision alongside the component drawing.
- Flag any contact whose material or finish remains undecided.
Sources: ASSDA Technical FAQ 1: Galvanic and Dissimilar Metal Corrosion
Describe the exposure rather than using a generic outdoor label
Salt and contamination can make wet deposits more conductive. ASSDA also explains that the relevant wetted areas can change as an assembly dries; the overall size of a rail is not a universal guarantee against localized attack around a fastener.
For the RFQ, ask the project owner for the available exposure assessment. Keep observations separate from assumptions. A brief site description is useful for an initial discussion, but the final material decision belongs to the responsible design team. Avoid converting a location name or a photograph into an unsupported corrosion rating.
- Provide known coastal, industrial or agricultural exposure information.
- Include relevant site photographs and any previous corrosion findings.
- Identify who will resolve unknown environmental conditions before release.
Sources: ASSDA Technical FAQ 1: Galvanic and Dissimilar Metal Corrosion; U.S. Department of Energy: Managing and Mitigating Solar PV Corrosion
Review corrosion protection and electrical bonding together
The U.S. Department of Energy describes solar assemblies that combine stainless fasteners, aluminum frames and metal supports. It also explains that bonding devices may intentionally penetrate anodizing to create an electrical pathway. Corrosion at such a connection can affect electrical continuity as well as the mechanical joint.
Treat an isolation washer, changed coating or replacement clamp as a proposed design change, not a universal purchasing fix. Ask the system designer to approve the complete configuration against its structural and electrical requirements. This guide does not provide instructions for modifying an installed array or its grounding connections.
- Mark whether the connection has an intentional bonding function.
- Keep the approved clamp, washer and fastener combination identifiable.
- Require design approval before accepting a proposed interface change.
Sources: U.S. Department of Energy: Managing and Mitigating Solar PV Corrosion
Consider inspection access when preparing the purchasing brief
Worldstainless notes that installed panels can conceal their fasteners, making later inspection difficult, and that dirt or pollutants can accumulate in hidden locations. The publication treats mechanical properties and corrosion resistance as important parts of fastener selection for solar installations.
As an editorial RFQ recommendation, discuss the planned maintenance responsibilities before ordering production quantities. Ask the owner which locations will be inspected and what documentation must remain available. Do not promise a service life from a generic material label, a catalogue photograph or the appearance of a new sample.
- Identify who maintains the assembly and reviews inspection findings.
- Specify the part and drawing references needed for future replacements.
- Agree how the approved configuration will remain traceable in project records.
Sources: Worldstainless: Stainless Steel in Solar Energy Use
Use a structured RFQ checklist for custom solar fasteners
For an enquiry to Chuanghe Fasteners, organize the approved inputs into one revision-controlled package. Request a feasibility response against those inputs and list the questions that remain open. This is a suggested buyer workflow, not a statement that a particular solar system, certification or validation capability has been confirmed.
Make quotations comparable by asking each bidder to identify deviations explicitly. A lower price based on a different mating finish, altered washer or undocumented substitution does not answer the same enquiry. Route proposed changes to the appropriate project engineer before the purchase specification is finalized.
- Fastener drawing: geometry, material designation and released revision.
- Assembly definition: mating materials, finishes, washers, clamps and receiving threads.
- Project information: known exposure conditions and the approved corrosion review.
- Functional scope: structural requirements and any intentional bonding function.
- Evidence: agreed inspection records, sample requirements and approval responsibilities.
- Change control: a written list of substitutions and unresolved items.
Sources: U.S. Department of Energy: Managing and Mitigating Solar PV Corrosion
Define acceptance evidence before production release
For corrosive solar sites, the Department of Energy recommends a systematic assessment that informs material selection, design and maintenance. An enquiry should therefore identify what project-specific review is needed rather than asking a supplier to guarantee an undefined environment.
At quotation stage, agree which documents will support acceptance and who has authority to approve them. Keep component inspection separate from system qualification: a dimensional report answers different questions from an assembly corrosion review. The following steps are our recommended procurement checks, not prescribed test settings or acceptance limits.
- Confirm that sample identifiers match the quoted drawing and finish revisions.
- Request evidence against the criteria agreed by the project design authority.
- Record remaining limitations and obtain disposition before production release.
- Keep the final approved specification with the order and inspection documentation.
Sources: U.S. Department of Energy: Managing and Mitigating Solar PV Corrosion
Frequently asked questions
Can stainless steel fasteners cause corrosion of aluminum parts?
Yes, a susceptible electrically connected and wetted couple can attack the more active aluminum. Assess the actual materials and exposure; the fastener's appearance alone does not establish that the whole connection is sound.
Sources: ASSDA Technical FAQ 1: Galvanic and Dissimilar Metal Corrosion
Should every solar mounting connection use an insulating washer?
Do not assume so. Some connections intentionally provide electrical bonding. Have the responsible system designer approve any isolation or coating change against the complete assembly requirements before purchasing or substituting hardware.
Sources: U.S. Department of Energy: Managing and Mitigating Solar PV Corrosion
What should a custom solar fastener RFQ include?
Include the released component drawing, mating materials and finishes, known site exposure, the approved functional requirements and the requested evidence. Identify who will review unresolved corrosion and bonding questions before production release.
Sources: Worldstainless: Stainless Steel in Solar Energy Use; U.S. Department of Energy: Managing and Mitigating Solar PV Corrosion
Related reading
- Custom Fastener Surface Treatment Specification Guide
- Materials for Custom Fasteners
- Custom Fastener Drawing and Inspection Guide
