A claim that a PV module is suitable for a dusty site needs more than a clean photograph or an abrasion-test logo. Request the exact glass and coating identity, the test specimen, the abrasive and exposure method, the measurement sequence, the acceptance rule and the limits of applying the result to your site. Keep removable contamination, persistent surface damage and electrical module performance as separate questions.
For a practical RFQ, ask each bidder to map its evidence to the same environmental description and maintenance plan. A coupon test can inform a material comparison without proving the lifetime of the complete module. A reported number of brush cycles is not a number of operating years unless a defensible correlation covers the proposed conditions.
This guide addresses procurement of abrasion evidence. It does not prescribe a field cleaning technique or a laboratory recipe. Model-specific maintenance permission remains with the applicable manufacturer instructions. The article makes no claim that SINAWATTS manufactures a particular coating, performs abrasion testing or has a tested module available; those details require confirmation for the proposed order.
Decide which surface problem the evidence must answer
Start with the observation or anticipated exposure. Loose surface deposits, adherent contamination, scratches, coating wear and glass damage are not interchangeable descriptions. A dusty appearance does not establish abrasion, and a panel that looks clean is not proof that its optical surface is unchanged.
Write one decision statement before collecting certificates. For example: determine whether the offered surface construction has relevant comparative abrasion evidence for a site with airborne mineral particles and a specified maintenance approach. This keeps the inquiry narrower and more answerable than a request for a generic desert-proof module.
Separate the screening decision from final product acceptance. Screening may eliminate a construction whose evidence does not address the relevant mechanism. Acceptance must also consider the complete module requirements, site design, warranted scope and commercial agreement. A strong result in one material test cannot close those other reviews.
The existing module cleaning requirements guide addresses allowable water, tools and maintenance records. Use it when defining how cleaning is authorized. The present guide asks a different question: what evidence supports the surface's response to abrasion under a stated exposure?
Describe the site without inventing a severity label
Provide the information actually known about the location: surrounding land use, nearby particulate sources, observed deposition, available particle analysis, weather records and proposed cleaning equipment. Mark missing data as unknown. A regional label such as coastal, arid or industrial is useful context but not a complete abrasive specification.
Distinguish windborne exposure from particles moved across a surface during maintenance. If both are relevant, identify both in the inquiry. The supplier or qualified test provider should explain how the proposed evidence addresses them and which part of the real exposure it omits.
Record whether the site information comes from measurements, photographs, neighboring installations or a preliminary planning assumption. Each has a different evidential weight. Photographs can establish visible contamination and location, but do not identify particle hardness, size distribution or the severity of contact with glass.
Do not turn an unknown environment into an extreme numerical test simply to appear conservative. A demanding test can still use an irrelevant mechanism. Ask the technical owner to justify the selected comparison and preserve its limitations in the bid review rather than hiding them behind a pass label.
Freeze the glass and coating construction being compared
The report should identify the substrate, surface treatment and coating configuration in enough detail to match the offered product. A commercial coating name alone may cover several formulations or application processes. Request controlled identifiers or a confidential cross-reference where proprietary details cannot be disclosed openly.
Identify which surface was tested. Front glass, rear glass, a backsheet and an applied coating do not become equivalent because they belong to the same module. For a bifacial construction, clarify which surfaces are covered by the evidence and whether the purchasing question concerns one side or both.
Ask how specimens were produced. A laboratory-coated coupon may differ from the surface made on a production line. The manufacturer should state the relationship between the sample construction and production, including any relevant process differences, without requiring the buyer to guess from matching color or appearance.
Use the glass and backsheet BOM change-control guide to connect the material record to the finished module revision. Freeze that connection before ranking results. Otherwise the buyer may approve one tested surface and receive another configuration under the same broad model family.
Read the abrasion standard at its actual scope
The public IEC 62788-7-3:2022+AMD1:2024 consolidated publication record covers methods for evaluating abrasion of PV materials and coatings. Its stated scope includes incident and rear surfaces and allows representative specimens as well as module specimens. This is a relevant method reference, not a universal site-life guarantee.
Ask the laboratory to identify the selected procedure, edition, specimen preparation, deviations and evaluation criteria. The public catalogue description does not provide the full instructions or a project-specific acceptance limit. Obtain the controlled method and qualified interpretation needed for the contracted work.
Treat an older report transparently. Its original edition and date must remain visible. A technical reviewer can assess whether it answers the present question or needs supplementary evidence; a buyer should not silently relabel it with the newest edition number because the title looks similar.
When a bidder provides a generic environmental certificate, request the actual page that identifies the tested surface and abrasion method. If that evidence is absent, mark the abrasion question unresolved. This is a document-scope finding, not proof that the product will fail at the site.
Match the test mechanism to the procurement question
Ask what physically contacted the sample: moving particles, a loaded contact tool, or another defined abrasive process. Request enough information to distinguish the method from unrelated dust exposure. A test focused on material entering an enclosure does not by its title establish optical surface durability.
For particle exposure, the useful return fields include abrasive identity, particle characteristics, delivery arrangement, specimen orientation and exposure quantity. For contact abrasion, request the tool identity, condition, applied motion and loading information specified by the method. These are evidence fields, not proposed operating settings.
The provider should explain whether wetting, drying, contamination renewal or other conditioning forms part of the sequence. An abrading tool acting on a clean specimen and the same tool moving deposited particles do not describe the same experimental setup. Preserve the difference in the comparison table.
Require deviations to be stated before comparing results. If a provider modifies a recognized procedure for project relevance, that may produce useful evidence, but the report must identify the modification. Do not present a custom comparative test as unqualified conformity to a method whose conditions were changed.
Ask what the research supports and what it does not
A five-year PV glass coating study in the NLR research repository examined glass coupons at several locations and compared cleaning approaches. Its reported evaluation combined optical characterization with microscopy of surface damage. That supports separating deposit coverage, optical response and surface condition in an evidence request.
It does not establish that a commercial module offered today has the same construction or will produce the study's outcomes. Do not transfer a ranking between research specimens into a supplier ranking without a documented material connection and comparable conditions.
The IIT Bombay NCPRE research summary on coating abrasion describes tests on four commercial hydrophobic coatings and identifies deposited dust and brushing conditions as influential in its setup. The purchasing implication is to request the complete test configuration instead of comparing cycle totals alone.
The published research is background evidence for asking better questions. This guide does not transfer its numerical lifetime ratios into a maintenance interval, select a brush for an installed module, or claim a quantified improvement for any SINAWATTS product. Those would require additional product-specific evidence.
Require a measurement sequence that separates residue from damage
Agree the measurement states before testing. A useful review distinguishes the documented starting surface, the surface after exposure and any subsequent condition after an approved deposit-removal step. The laboratory should decide which states and preparation steps are appropriate to its method and the purchasing question.
Ask whether the final optical measurement includes residual particles. A lower measured transmission may reflect remaining deposits, surface change or both. Without the state definition, a headline percentage cannot tell the buyer which conclusion the report supports.
Any removal step must itself be recorded. Its chemistry, tool and process could change the surface being examined. Use a controlled procedure and an appropriate comparison or control where the technical owner requires it. Do not improvise aggressive cleaning to make an unfavorable result disappear.
Preserve intermediate results even when the contract uses only one final value. Their role is to explain the sequence and support an investigation, not to multiply acceptance criteria after testing. A well-indexed appendix can keep the main report readable while retaining the evidence needed for a later dispute.
Specify the evidence package before requesting prices
Give bidders a common response schedule so that missing evidence is visible before quotation comparison. The following fields organize procurement; the selected test method remains the source of technical procedures and the approved specification remains the source of limits.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Evidence field | Required return | Clarification that blocks comparison |
|---|---|---|
| Product link | Module revision and tested glass/coating identifiers | Coupon cannot be mapped to the offered construction |
| Specimen scope | Coupon or module, quantity and preparation | Sample type or production relationship omitted |
| Abrasion method | Document, edition, selected procedure and deviations | Generic sand-resistant claim only |
| Exposure | Abrasive, contact arrangement and recorded sequence | Cycle count without its conditions |
| Measurement states | Baseline, exposed and any cleaned condition | Residue and surface change combined without explanation |
| Evaluation | Quantity, units, method, uncertainty and criterion | Pass claim with no applicable limit |
| Transfer limits | Supported inference and untested site conditions | Laboratory exposure converted to years without a basis |
Ask the bidder to identify which documents already exist and which would require new work. A proposal to commission a report is different from an existing report. Price and schedule should distinguish them, and the acceptance decision should remain pending until the agreed evidence is available.
Send the module reference, surface construction and site exposure description with your RFQ. Include the documents already held and request a written response identifying missing evidence, scope limitations and any proposed third-party work.
Use optical measurements without promising electrical yield
State exactly what is measured and how the comparison is calculated. Transmission, reflection, haze and electrical power are different quantities. A supplier's chart must identify the quantity, spectral or other measurement conditions where relevant, baseline convention and sample identity before it can support a useful comparison.
Do not treat a change in one optical value as the same percentage change in annual energy yield. A module and an operating array introduce other conditions beyond the test coupon. If an electrical or yield conclusion is required, ask for a separate justified analysis and its assumptions.
Request individual specimen results alongside any summary. An average can conceal a damaged specimen or an inconsistent process. Decide in advance how variation, invalid measurements and missing specimens affect the comparison, rather than choosing whichever summary makes a preferred bid appear strongest.
A result near an acceptance boundary needs the agreed measurement decision rule. Ask how uncertainty, repeat measurements and rounding are handled. The buyer should not add decimal places or create a new tolerance after reviewing results. Any uncertainty about disposition belongs with the designated technical authority.
Work through hypothetical optical-state readings
Consider three explicitly fictional transmission readings on one specimen under the same defined measurement conditions: 90.0% at baseline, 88.0% after exposure and 89.5% after a controlled deposit-removal step. These numbers illustrate arithmetic and review questions only. They are not test results, expected product performance or an acceptance criterion.
The change from baseline to the exposed state is 2.0 percentage points. Relative to the 90.0% baseline, that is about 2.22%, calculated as 2.0 divided by 90.0. The rise after deposit removal is 1.5 percentage points, leaving a difference of 0.5 percentage point from baseline, or about 0.56% of the baseline value. Keep percentage points and relative percentages clearly labeled.
The observed recovery is consistent with a removable contribution, but the readings alone do not establish its cause. The remaining difference does not prove abrasion: residual contamination, the removal procedure, measurement variation or surface change may require investigation. Review controls, surface observations and uncertainty before attributing the difference to any mechanism.
A useful supplier clarification would identify the removal method, control specimen, individual readings and uncertainty basis, then explain what conclusion is supported. Do not simply classify the remaining 0.5 point as coating loss or convert it into an electrical-power or annual-yield penalty. The acceptance decision still follows the agreed requirement and decision rule.
Compare three hypothetical evidence packages
Consider a hypothetical project comparing three surface configurations for the same module purchase. The buyer has identified airborne mineral particles and a proposed dry-contact maintenance system as relevant exposures. No test result or numerical performance limit is supplied in this example; the exercise compares evidence completeness only.
Offer A supplies a short certificate stating that a glass coupon passed sand testing. The report does not identify the coating revision or the coupon's relation to production. The proper action is to request that mapping and method detail, not to conclude either excellent or poor desert performance.
Offer B supplies a traceable coating-coupon report for a defined contact-abrasion method, with baseline and post-test optical measurements. It states that no wind-driven particle procedure was included. This is useful evidence for one part of the question, but its explicit exclusion remains open for technical review.
Offer C provides the same relevant mapping plus a separate, documented particle-exposure assessment. Its test surfaces and measurement states are identifiable, but its maintenance assumptions differ from the buyer's proposed equipment. That difference needs resolution before either report is accepted as directly applicable.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Hypothetical offer | Useful evidence | Remaining decision |
|---|---|---|
| A: generic coupon certificate | A claimed test exists | Confirm method, construction and report scope |
| B: mapped contact-abrasion report | Defined evidence for one mechanism | Assess the uncovered airborne-particle question |
| C: two mapped assessments | Evidence addresses two mechanisms | Reconcile the actual maintenance configuration |
The comparison does not select a winner. Commercial ranking follows the evidence review. An explicit limitation can make a bid easier to assess than a broad promise, but a limitation still has to be accepted or resolved by the responsible buyer rather than silently removed from the purchase order.
Turn a cycle claim into a reviewable statement
A supplier may advertise thousands of cleaning cycles. Ask what one cycle means, what surface and tool were used, whether particles were replenished, how specimens were evaluated and which criterion ended the test. Different cycle definitions can make identical totals incomparable.
Keep the recorded experimental exposure and any service-life model in separate fields. The first is a test observation; the second is an inference that requires assumptions and validation. If a model exists, request its environmental range, maintenance assumptions and evidence connecting laboratory exposure with field behavior.
Do not accept a simple division by anticipated cleanings per year as proof of years of module durability. It ignores whether the laboratory and site mechanisms are comparable. Such arithmetic can describe a schedule assumption, but it cannot by itself establish a validated acceleration relationship.
If the supplier cannot support the time conversion, retain the useful laboratory evidence in its original units and remove the unsupported life claim from the acceptance rationale. This often preserves a workable comparison without discarding every document or pretending that an unresolved forecast has become a proven rating.
Resolve evidence gaps with specific owners and outcomes
Assign each open question to the organization able to answer it. The manufacturer should map the tested construction to production. The laboratory should explain the procedure and measurement record. The site owner should supply the environmental and maintenance assumptions used for the purchase decision.
Use precise requests. Instead of asking for more certificates, request the report page identifying specimen coating revision R2, the document linking R2 to the offered module, or the missing description of the post-exposure surface condition. Specific requests reduce unproductive exchanges and make responsibility clear.
Record one of three outcomes for each requirement: evidence accepted for the stated purpose, clarification pending, or evidence outside the required scope. These are procurement review states. They should not be confused with laboratory pass/fail results or a guarantee about future field performance.
Close a pending item only with the referenced response and the designated approval. If a bidder proposes a different construction or method to resolve it, update the affected comparison instead of attaching the new certificate to an unchanged old product description. Retain the earlier record as history.
Keep receipt checks and production changes tied to the decision
After award, ensure the delivered module documentation identifies the approved construction or its controlled manufacturer mapping. Receiving staff should check identity and visible condition against the agreed plan. They should not invent a field abrasion test by rubbing a production module with locally available sand or tools.
When damage or unusual surface appearance is found, record the unit, location, photographs and handling history and follow the agreed quarantine or escalation procedure. A scratch observed at receipt is evidence of a condition; its cause should be investigated rather than automatically attributed to manufacturing, transport or cleaning.
Require notification of relevant changes to glass source, coating, surface treatment or production mapping. The technical reviewer decides whether existing evidence remains applicable. A supplier's assurance that the new version is equivalent should identify the basis for that conclusion and any limitations.
The solar accessories overview provides related sourcing navigation. It is not evidence of any specific module's abrasion rating, certification, stock or test service. Keep offered product identity and confirmed commercial scope in the written quotation and order documents.
Buyer FAQ
Does a dusty module necessarily have abrasion damage?
No. Visible deposits and damage to the underlying surface are different findings. Request an appropriate examination and a defined measurement state before interpreting performance. Document any approved deposit-removal step because that process can affect the surface too. A photograph alone cannot establish particle properties, coating loss or the cause of an optical change.
Can a coupon report support a complete module purchase?
It can support a defined material question when the tested surface is mapped to the offered construction. Ask what the coupon represents, how it was produced and which conclusions transfer. Do not use it as a replacement for complete-module evidence or assume it covers frames, seals, junction boxes, electrical safety and the entire operating environment.
Does compliance with an abrasion method guarantee desert lifetime?
No universal lifetime follows from a method reference. Request the actual procedure, conditions, result and acceptance basis, then review relevance to the site. Any forecast in years needs its own supported relationship between laboratory exposure and field conditions. Keep unvalidated time conversions out of the purchase acceptance rationale even when the underlying test remains useful.
Is the highest reported cycle count the best quotation?
Not without comparable definitions. Establish what constitutes a cycle, the abrasive and tool configuration, specimen identity, measurement sequence and termination criterion. A larger total from a different method may answer a different question. Compare evidence against the requirement first, then review the complete technical and commercial offer rather than sorting one number in isolation.
Can published research approve our proposed cleaning machine?
Research can identify relevant mechanisms and useful evidence fields, but it does not automatically grant manufacturer permission for a machine on your module. Obtain the exact model's applicable maintenance instructions and any required written clarification. Keep surface-durability assessment separate from work authorization, electrical safety procedures and the manufacturer's actual warranty terms.
What if one report omits the offered coating revision?
Ask for a controlled manufacturer cross-reference or a report correction supported by traceable records. Do not add the revision yourself or assume that matching brand names prove identity. If the mapping cannot be established, preserve the report as background information and hold the construction-specific conclusion until suitable evidence or an accepted alternative is provided.
What should be included in the first abrasion-evidence inquiry?
Send the module model, available glass and coating identifiers, site description, proposed maintenance approach and intended acceptance decision. Attach existing reports and identify uncertainties. Request the test scope, construction mapping, measurement sequence, limits of application and commercial exceptions. Confirm quantity, availability, price, document access and any new testing schedule with the supplier rather than assuming them.
Request an abrasion comparison tied to the offered surface
Send the proposed module construction, exposure assumptions and available abrasion reports for RFQ review. Ask for a response that separates documented evidence, unresolved applicability and optional additional work. The final order should identify the accepted construction and the conclusions the evidence actually supports.