Table of Contents
A solar panel warranty usually contains two different commitments: coverage for defects in the product and coverage for maintaining a defined power output. A longer period beside the word “performance” does not mean that every damaged module will receive a free replacement throughout that period. It also does not establish guaranteed annual generation for the complete solar installation.
A business owner needs to know which document applies to the modules actually supplied, what will be tested and which costs remain after a claim is accepted. This guide covers checks before purchase and evidence preparation after a problem appears. Its numerical example is hypothetical and describes neither a particular model nor an ONG Solar warranty offer.
Separate product coverage from power output coverage
A product warranty concerns the material and manufacturing defects defined in the document. Its terms establish the covered faults, how their cause is assessed and the applicable exclusions. Broken glass needs an assessment of its origin: external impact and a manufacturing defect cannot automatically be treated alike.
A power warranty establishes a lower output limit at a given stage of the warranty period. It can last longer than product coverage while using its own criteria. Expiry of one period does not answer whether the other commitment applies. Read both sections alongside the general conditions.
| Question | Product warranty | Power warranty |
|---|---|---|
| What is assessed? | A covered product defect | Output below the defined power limit |
| What is the basis? | Description and evidence of the fault | Power curve, reference value and agreed measurement |
| Which period applies? | The period for the relevant model | The period for the relevant model |
| How is it resolved? | Under the stated remedy procedure | Under the stated remedy procedure |
The module manufacturer's warranty, seller obligations, installation workmanship and paid maintenance have different scopes and responsible parties. Identify the party handling each process in the supply documents.
Find the document that applies to your supply
Start with the complete module designation, including suffixes. Similar commercial names can cover different constructions and conditions. Compare the specification, invoice, label and model list in the warranty document. Check whether it covers the relevant monofacial or bifacial version.
Record the revision, document date, territory and event that starts the warranty clock. The rule may involve purchase, delivery, installation or manufacture. Preserve evidence of the required dates and apply the stated rule, rather than choosing the latest date yourself.
An English document described as global can contain territorial exceptions. Finding it online does not establish coverage for a Ukrainian shipment. Before payment, request written confirmation of the applicable revision and eligible purchasing channel. Where registration or an extension is required, establish the conditions, deadline and proof of completion.
A newer online revision does not necessarily replace an earlier purchase agreement. Keep the agreed document set. If a seller offers broader coverage, record that seller's separate obligation and responsible entity. Reconcile conflicting buyer details, installation locations, equipment lists or attachments before accepting the supply.
Read the linear curve as a defined lower limit
A linear power warranty sets a lower boundary rather than predicting exactly how every panel will age. Identify the initial reference in watts, the permitted first-year reduction and the rule for later years. When deductions use the original reference, percentage-point reductions must not be replaced with annual multiplication of the remaining output.
Warranty measurements often refer to standard test conditions, abbreviated STC. Find the specified conditions, method, accepted testing facility and treatment of measurement uncertainty. An inverter reading on a hot afternoon does not directly measure an individual module's rated output under those conditions.
For bifacial modules, check whether the document provides a separate warranty for the rear side and, if so, which conditions apply. Do not add an expected gain from reflected light to the warranted reference without a corresponding provision. Roof generation also depends on sunlight, layout, shading and the rest of the equipment.
Check the arithmetic with a hypothetical example
Imagine a fictional document using a 500 W reference, a 2% first-year reduction and a further 0.4 percentage-point reduction each year against the same original reference. Its hypothetical term is 25 years. These inputs illustrate arithmetic only; they are neither a typical requirement nor product specifications.
At the end of year n, the lower boundary is 500 × [1 - 0.02 - 0.004 × (n - 1)]. Year one gives 490 W. Year ten gives 500 × [1 - 0.02 - 0.004 × 9] = 472 W, or 94.4% of the reference. Year 25 gives 500 × [1 - 0.02 - 0.004 × 24] = 442 W, or 88.4%.
The difference between 500 W and 472 W establishes neither automatic compensation nor annual lost kilowatt-hours. An actual claim requires an agreed measurement, its uncertainty and the applicable conditions. For real equipment, use its documented reference, curve and term, preserving the origin of every input.
Create the baseline file before commissioning
Keep the supply specification, purchase records, warranty conditions, manuals and any required registration confirmation. Create a searchable serial-number register linked to row, position and electrical group. Label photographs should support the register without replacing the ability to locate an individual panel.
Record the initial visible condition, acceptance and installation dates, and available test results. Delivery damage needs its own history rather than first appearing years later as an unexplained manufacturing fault. Keep original files and recognizable version names.
During solar system design, agree the documentation that the owner will receive after startup. Include the module register, layout and installation information. After replacing a panel, update its serial number, position and installation date while retaining the previous unit's history.
Distinguish a monitoring signal from proof of a defect
A lower monthly yield warrants investigation but does not prove excessive module degradation. First examine data completeness, weather, outages, curtailment, soiling and shading. The guide to forecast versus actual solar generation explains that comparison.
Identify the observation's boundary: one module, a series-connected group, an inverter or the whole site. Different boundaries require different evidence. Preserve when the symptoms appeared, preceding events and available records without arbitrarily correcting original data.
A thermal image can identify an area for further examination. It does not itself measure warranted output or establish a manufacturing cause. The thermal inspection report checklist helps assess the evidence. Qualified personnel determine diagnostic methods and safe actions.
Before commissioning expensive tests, confirm the accepted facility, samples, method and report format with the responsible warranty party. A privately commissioned diagnostic report may need further verification for a claim. Agree removal and testing before altering the equipment or incurring transport costs.
Prepare a claim with evidence and authority
Check who can submit: the original purchaser, current owner or an authorized representative. Ownership changes require the applicable transfer conditions and records. Buying used panels or moving an array to another building does not automatically establish continued coverage.
Use this preparation list, adding the exact requirements of the applicable document:
- Claimant details, authority to act and a contact for replies.
- Affected models, quantities, serial numbers and installation positions.
- Purchase evidence and records establishing the warranty start date.
- Symptoms, discovery date, photographs and associated operating records.
- Available test reports identifying method, conditions and provider.
- Installation, maintenance, repair and configuration change history.
Check the notification deadline and channel immediately rather than waiting for a lengthy private investigation. Obtain a case number and written next steps. Agree removal, return and additional testing in advance, including packaging and responsibility for preserving the equipment.
Compare remedies with the associated costs
An accepted claim may lead to repair, replacement, additional modules or a document-defined financial remedy. Check who chooses and how the amount is calculated. The valuation basis defined by the document does not necessarily mean repayment of the original cost of the complete installation.
Clarify diagnostic fees, removal, lifting equipment, packaging, transport insurance, delivery and reinstallation separately. Ask what changes if testing fails to establish a breach. The conditions may allocate costs to different parties. Check lost-generation or downtime compensation separately too.
If the original model is discontinued, assess a proposed replacement's electrical compatibility, dimensions and mounting requirements. Establish the remaining warranty period after replacement. Organize these tasks and their charges through the solar maintenance agreement.
Keep the written resolution, replaced serial numbers and return-to-service checks. Modules excluded from a partial resolution should retain a visible status. Closing a correspondence ticket should not erase unresolved issues. Hand over the updated file alongside the claim history.
Record the decision before ordering modules
Compare proposals using one consistent record: exact model, applicable revision, both periods, output curve, claimant eligibility, evidence requirements, remedies and owner costs. Mark outstanding questions and obtain answers before agreeing the supply. A longer term alone does not resolve an unclear procedure.
For an existing installation, provide the equipment list, available documents and event history to discuss the necessary solar maintenance scope. Diagnosis, the manufacturer's warranty decision and the resulting work need separate agreement. A prepared file helps identify the next check and responsible party using the actual conditions.