“Hail tested” is not a comparable specification. One report may use baseline design-qualification impacts. Another may test larger ice balls, different velocities or different strike locations. A third may describe an entire roof-PV approval. Even when two tests use the same nominal diameter, impact energy can differ because velocity is squared in the kinetic-energy equation.
The buyer needs a chain from site hazard to test severity, from test severity to an exact module construction, and from each impact to post-test electrical and safety evidence. Glass survival alone is insufficient. A module can retain apparently intact glass while developing cell cracks, interconnect damage, insulation problems or later moisture paths.
This guide is separate from the module mechanical-load guide, which addresses distributed pressure/suction and support geometry, and from the solar panel packaging and pallet-storage guide, which addresses handling/transit damage. Hail is a localized, high-rate impact; static uniform pressure and shipping shock do not substitute for it.
Nothing here verifies a SINAWATTS module, hail rating, certificate, laboratory, manufacturing process, tracker control, stock, price, MOQ, lead time or field outcome. Use current written evidence from the module manufacturer, qualified laboratory, approval body, project engineer, insurer and authority having jurisdiction.
Direct answer: what must a hail RFQ contain?
For every offered module model, require:
- exact manufacturer, sales model, construction suffix, dimensions, mass, front/rear glass or backsheet construction, frame code and controlled BOM revision;
- project hail hazard source, map/version, return period and required performance category;
- governing baseline qualification and any additional hail test standard, edition and approval scheme;
- ice-ball material/preparation, nominal diameter, measured mass, conditioned temperature and allowed tolerances;
- measured velocity for every shot and resulting kinetic energy, with calibration/measurement method;
- angle and surface of impact, module orientation and support/mounting arrangement;
- marked impact map showing cells, busbars/interconnect regions, glass edges/corners, frame proximity, junction-box/diode region and repeated locations where applicable;
- number of modules, number of impacts and test sequence;
- pre/post visual inspection, maximum-power/I-V, insulation and wet-leakage results as required, plus agreed electroluminescence/infrared diagnostics;
- report, certificate/approval and exact sample-to-offered model mapping;
- glass/BOM change control and any worst-case selection rationale; and
- operational mitigation where relevant, including tracker stow logic, weather input, fail-safe state and wind-load verification in the hail position.
Do not accept a single “XX mm hail” cell without velocity, energy, impact locations and post-test criteria.
Convert diameter and velocity into impact energy
Kinetic energy is:
E = ½mv²
where m is ice-ball mass and v is impact velocity. Because velocity is squared, a modest velocity change can materially alter energy. Diameter influences mass approximately with volume for comparable ice density, but actual balls should be weighed because voids and preparation vary.
The RFQ should preserve all three values: nominal diameter, measured mass and measured velocity. Calculate energy for each shot rather than from a marketing category alone. Record units and tolerances.
Example, for comparison method only: if Ball A and Ball B have equal mass but Ball B arrives 10% faster, Ball B’s kinetic energy is about 21% higher because 1.1² = 1.21. This does not set an acceptance level; it shows why diameter without velocity is incomplete.
Impact momentum, contact shape, hardness, fracture/fragmentation and incidence angle also affect damage. Kinetic energy is an essential comparison field, not a complete damage model. Use the governing test method rather than creating an improvised energy-equivalent substitute.
Start with the project hail hazard
Identify whether the project is roof-mounted, fixed ground-mount, single-axis tracker, carport or another configuration. Use the insurer/project-authorized hail hazard source and record its edition, coordinates and return-period basis. A country or state label is too coarse for a bankable project.
FM’s April 2026 Property Loss Prevention Data Sheet 7-106 for ground-mounted PV provides a public example of risk categories. Its table gives minimum equivalent hail size and impact energy of 38 mm/11 J for moderate hail, 44 mm/19 J for severe hail and 64 mm/72 J for very severe hail. It also recommends defensive hail stow for variable-tilt arrays in damaging hail-prone zones and requires consideration of worst-case wind loading in the hail-stow position. FM Data Sheet 7-106.
Those numbers belong to FM’s loss-prevention framework and should be applied only when the project/insurer adopts it. They do not replace local code, site meteorology or another insurer’s criteria. Record who selected the hazard and what acceptance is required.
FM’s April 2026 roof-mounted PV Data Sheet 1-15 likewise states that proper hail rating is important and cautions that manufacturer hail information must be checked for kinetic energy. It explains that inadequate hail resistance can lead to broken glass, component damage and moisture entry. FM Data Sheet 1-15. Its scope is roof-mounted systems; use the correct FM document for the actual project.
Establish the baseline qualification without overstating it
IEC 61215-2:2021 is the current edition displayed in the IEC catalogue on the source-check date. It provides design-qualification test procedures for terrestrial flat-plate PV modules. IEC 61215-2:2021 official scope. Ask the supplier for the exact report section that documents the hail test, samples, construction and results; do not infer details from the public catalogue summary.
Baseline qualification is valuable, but site hazard may justify additional severity or an approval scheme. A module that passed the applicable IEC sequence should not be described as immune to every hailstone. IEC 61215-1:2021 explicitly says qualification results are not a quantitative prediction of module lifetime and field life depends on design, environment and operating conditions. IEC 61215-1:2021 official scope.
Keep statements precise:
- “qualified to IEC 61215 under report X for models Y” is a scope claim;
- “tested with D-mm ice balls at V m/s at the mapped locations under report Z” is a severity claim;
- “approved/listed under scheme A for exact models” is an approval claim; and
- “suitable for this project hazard” is a project decision requiring the first three plus engineering/insurance review.
Do not collapse them into “hailproof.”
Define ice-ball preparation and measurement
The report should describe mould, water, freezing method, storage temperature, conditioning and time from removal to impact. Ice balls with cracks, air voids or irregular shape can behave differently. Record rejection criteria.
Measure diameter and mass for the test method’s required sample. Document the velocity instrument, location relative to the module, calibration and result for each accepted shot. A launcher setting is not the same as measured impact velocity.
Request the shot log:
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Shot | Module serial | Target location | Actual location | Diameter | Mass | Velocity | Energy | Valid/repeat | Observation |
|---|
If a shot misses the allowed target tolerance, the report should state whether it was repeated and how extra unintended impacts were treated. Selective omission can make a damaged sample appear cleaner.
High-speed video can support verification of impact/fragmentation and actual location, but it does not replace calibrated velocity measurement unless the approved method uses it accordingly.
Map impact locations to vulnerable construction features
A centred hit is not necessarily worst case. A complete plan should cover method-required locations and project additions such as:
- cell centres and cell edges/corners;
- inter-cell gaps, busbar or ribbon regions;
- glass centre, unsupported span and near support;
- glass edge/corner and frame-adjacent zones;
- junction-box or bypass-diode vicinity when the method calls for it;
- points over rear rails, purlins or torque tubes if support sensitivity is investigated;
- drainage/notch or mounting-hole regions for specialty modules; and
- representative zones for half-cut, shingled or other cell layouts.
The impact map should use module coordinates tied to a photograph/drawing. Mark actual, not only intended, hit location. If the project requests repeated hits near one region, distinguish that sequence from the baseline qualification.
Do not create a custom map and label it “IEC test” unless the standard method recognizes it. Report baseline and supplemental impacts separately. Supplemental evidence can be useful but should remain traceable.
Fix mounting, angle and module state
Support conditions influence bending waves and glass stress after impact. Record mounting orientation, clamp or bolt points, rail/purlin geometry, tightening condition and module angle. The setup should follow the governing method and claimed product configuration.
For trackers, testing a module flat may still be the prescribed laboratory configuration, while project mitigation can tilt the module before a storm. These are different evidence layers. The module test establishes product response under its method; tracker stow analysis addresses the installed system and forecast/control reliability.
Impact angle changes normal energy and damage mode. Preserve the test method’s incidence angle. Do not compare a normal impact directly with a glancing project exposure by simple cosine arithmetic unless the governing engineering method permits it.
Record module preconditioning and temperature. Glass and polymer behavior can change with temperature. If the test is performed outside a required range, document the deviation and disposition.
Require more than “glass did not break”
Post-impact acceptance should follow the governing standard/approval and any pre-agreed project additions. Obtain actual results, not only a certificate conclusion.
Useful evidence includes:
- high-resolution front, rear, edge and impact-point photographs;
- visual inspection for glass crack, chip, craze, frame damage, delamination, backsheet/rear-glass damage and junction-box disturbance;
- maximum-power/I-V comparison with controlled conditions and uncertainty;
- insulation and wet-leakage tests where required;
- electroluminescence images before and after with consistent acquisition;
- infrared imaging under controlled current/irradiance where specified;
- continuity or bypass-diode function checks where applicable; and
- observation after a defined dwell if delayed cracking is part of the agreed plan.
EL can expose cell microcracks not visible through glass. A crack does not automatically equal the same performance/safety outcome in every design, so define classification and acceptance before test. Do not accept post-test EL without a comparable baseline.
Wet-leakage or insulation evidence is particularly important after glass or rear-layer damage because moisture pathways affect safety. A dry visual pass cannot substitute for required electrical safety checks.
Reconcile report samples with the offered BOM
Hail response can change with front-glass supplier, thickness, heat treatment, coating, cell layout, encapsulant, rear construction, frame and support. Obtain a tested-to-offered construction matrix.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| Field | Hail-tested sample | Offered module | Evidence/disposition |
|---|---|---|---|
| Model/suffix | Report identity | Quoted identity | Exact mapping |
| Front glass | Code, thickness, treatment, coating | Controlled BOM | Same/change assessment |
| Rear layer | Backsheet/rear glass | Controlled BOM | Same/change assessment |
| Cell layout | Type, dimensions, count | Offered layout | Same/change assessment |
| Frame/support | Profile and mounting | Project configuration | Applicable scope |
| Factory/line | Sample source | Production source | Certification/QMS mapping |
IEC TS 62915:2023 supplies the current IEC approach for retesting after materials/design modification and includes a comprehensive change matrix. IEC TS 62915:2023 official scope. Require the manufacturer or certification body’s written disposition; do not decide from glass thickness alone.
The glass and backsheet BOM change-control guide provides the detailed alternate-material workflow. Freeze the hail-tested construction or document every approved alternate and serial range.
Distinguish baseline, severe-hail and insurer approval claims
Some suppliers advertise larger-diameter hail tests. Compare the complete conditions. A credible severe-hail package identifies standard/scheme, ball diameter/mass, velocity/energy, impact map, samples, mounting and post-test results.
FM states that ANSI/FM 4476, ANSI/FM 4478 and FM 4480 address performance against hazards including hail, fire spread and wind within their respective product/system scopes. FM renewable energy risk overview. Use the current approval guide and exact model record when an FM-approved product/system is required; a press release or “tested to” statement is not the approval listing.
Canadian Solar’s July 2026 official release says named U.S.-manufactured TOPCon and HJT hail-resilient module lines received FM Approvals recognition under identified FM standards for severe-hail zones. Canadian Solar severe-hail announcement. That is a manufacturer statement about specific products. Buyers must still obtain the current FM record, exact model/BOM, site requirements and mounting conditions. It does not establish approval for all Canadian Solar models or another supplier.
Avoid “passed 55 mm hail” comparisons that omit velocity. Ask whether the test used an approval-standard condition or a custom demonstration. A custom test can be useful project evidence, but label it accurately.
Evaluate tracker hail-stow mitigation as a system
For variable-tilt arrays, a hail-stow strategy may reduce exposed normal area or change the impact angle. It also changes wind loads and can fail if alerts, communications, power or actuators are unavailable.
Require:
- approved stow angle and the engineering basis;
- maximum time to move the array from any operating position;
- weather-alert source, thresholds, geographic coverage and latency;
- command hierarchy, local/remote control and cybersecurity provisions;
- backup power and behavior during grid/communication loss;
- wind-load capacity in the hail position for coincident storm winds;
- drainage, row collision, torque-tube and foundation checks;
- functional testing, maintenance and event logs; and
- residual hail risk when stow does not occur.
FM 7-106 explicitly connects defensive hail stow with worst-case wind design in that position. Do not optimize hail angle while ignoring wind. The tracker manufacturer and project engineer must approve the combined state.
Stow is mitigation, not a way to erase module test requirements. Weather forecasts can miss localized hail, and mechanical systems can be unavailable. Select an acceptable baseline module and then credit operational measures within the insurer/project method.
Inspect production, shipping and installation damage
Existing microcracks or edge damage can reduce impact margin. Control glass handling, pallet support, forklift contact, frame twisting and clamp installation. Receiving inspection should identify broken/chipped glass, frame deformation, package impact and moisture.
Use pre-installation EL sampling only when the project has a controlled method, equipment, interpretation and disposition. Informal images taken with different exposure are not comparable. Tie samples to serial numbers and pallet/lot.
At installation, keep clamps/supports inside the manufacturer’s permitted configuration. Hail evidence from one support arrangement cannot justify arbitrary short-side clamping or modified frames. Do not drill frame holes or allow hardware to contact glass/rear layers.
After a hail event, establish a safe inspection plan. De-energization, electrical hazards, broken glass and roof access require competent procedures. Use event data, visual/thermal/electrical testing and statistically justified sampling; do not assume every intact-looking module is undamaged, and do not condemn every module from one photograph.
Define post-event acceptance before the storm
The owner should have a documented response covering:
- weather/event data capture;
- safety isolation and access;
- drone/ground visual screening;
- string-level electrical comparison;
- sample selection for EL, insulation/wet leakage or laboratory testing;
- defect classification and escalation;
- warranty/insurance notification;
- replacement matching and change control; and
- return-to-service approval.
Sampling must account for array zones, module orientation, stow success, observed impact and manufacturing lots. Testing only convenient undamaged rows creates bias.
Do not promise that a pre-purchase hail rating guarantees zero claim. It reduces uncertainty within the tested and project conditions. Residual risk remains from larger/faster hail, repeated impacts, windborne debris, installation damage and operational failure.
Build a comparable hail-evidence matrix
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| RFQ field | Acceptable return | Hold point |
|---|---|---|
| Site hazard | Authorized map/category, coordinates, return period and target | “Hail area” |
| Module identity | Exact model/BOM/frame and serial scope | Marketing family |
| Test method | Standard/scheme, edition, report and laboratory | “Hail tested” |
| Projectile | Diameter, mass, preparation and tolerance | Diameter only |
| Severity | Measured velocity and calculated/recorded energy per shot | Launcher setting |
| Impact map | Intended/actual points, module count and repeats | Centre hit photograph |
| Setup | Mounting, angle, support and environmental condition | Unspecified fixture |
| Post-test | Visual, power, safety and agreed EL/IR results | “No broken glass” |
| Change control | Tested-to-offered mapping and retest disposition | Same wattage/same glass claim |
| Operations | Hail stow, alerts, backup, wind check and logs where used | Manual stow without response analysis |
Compare evidence completeness and project adequacy before module price. A larger nominal hailstone with unreported velocity or model mapping is not necessarily stronger evidence.
Send a complete hail-resilience RFQ
Issue site coordinates, adopted hail hazard, insurer requirements, module/mounting concept, tracker operation, required qualification/approval and post-event plan. Ask bidders to return the completed matrix and every report limitation.
Request price, MOQ, production site, sample/test cost, test lead time, module supply lead time, packaging, warranty and replacement strategy as written commitments for the exact model. This guide provides none of those commercial facts.
When hazard, module identity and test conditions are aligned, send the hail-evidence RFQ. Attach the impact-map and post-test data requirements so bids can be compared without relying on “hailproof” language.
Buyer FAQ
Is ice-ball diameter enough to compare two hail tests?
No. Compare measured mass, velocity and kinetic energy, plus impact angle, locations, module mounting and post-test criteria. Energy changes with the square of velocity.
Does IEC 61215 qualification prove survival of every local hailstorm?
No. It is defined design-qualification evidence. Site hazard, larger or more energetic hail, repeated impacts and project/insurer requirements may justify additional testing or mitigation.
Can static mechanical-load data replace hail testing?
No. Static mechanical load is distributed pressure applied over time; hail is localized high-rate impact. The stresses and failure modes differ.
Why record actual impact locations?
The launcher can miss the intended point within a tolerance, and different locations have different vulnerability. Actual-location records show whether cells, edges, interconnects and other sensitive areas were truly exercised.
Does intact glass mean the module passed?
Not necessarily. Apply the governing acceptance criteria, including required electrical/safety measurements. EL or other controlled diagnostics may reveal internal damage, while insulation/wet-leakage testing can address safety after impact.
Is severe-hail testing automatically an FM Approval?
No. A custom or third-party severe test is not the same as a current FM Approval listing. Verify the exact model in the applicable approval record and all system conditions.
Can a different glass supplier use the old hail report?
Only with a documented change assessment and applicable retest/qualification disposition. Glass code, thickness, treatment, coating and edges can affect response.
Does tracker hail stow eliminate module hail risk?
No. Alerts or actuators can fail, storms can develop rapidly, and hail can arrive at varying angles. Stow must also be checked for coincident wind. Treat it as system mitigation alongside module evidence.
What evidence should be collected after a field hail event?
Capture event and stow logs, inspect safely, map damage, compare electrical performance and apply a statistically justified diagnostic plan. Coordinate warranty, insurer and engineering disposition before return to service.
Can one tested power bin cover an entire module family?
Only if the report/certificate and manufacturer mapping support the family, including glass, cell layout, frame and construction variants. Obtain the exact model annex and retest rationale.
Why include kinetic energy when FM categories already use hail size?
FM’s own public tables pair equivalent diameter with energy, recognizing that damage severity is not described by diameter alone. Preserve the project’s adopted category and the actual test shot data.
Does this guide verify a SINAWATTS hail rating?
No. It is a procurement framework. Require current manufacturer, laboratory, approval-body, insurer and engineering evidence for the exact product and project.