Photovoltaic assessment: commissioning the right investigation
An assessment should answer a specific question. Reduced output, visible damage, handover checks and assessment before purchase do not automatically need the same investigation. Define the goal and clarify methods, reporting and limitations.
The question determines the scope
Describe what you need to establish without prescribing a technical cause. An investigation after hail or installation concerns differs from an output forecast. A maintenance report or brief visual inspection is not automatically a reasoned expert assessment.
| Purpose | Clarify |
|---|---|
| Reduced output | Period, comparison data and potential further investigations. |
| Damage | Areas affected and required documentation. |
| Handover / assessment | Checks, available records and assessment goal. |
Check expertise and independence
Expertise differs by discipline. Electrical systems, roofing and structure, output analysis and reflections are different areas. Establish which questions the appointed specialist can address and whether other expertise is needed.
For an independent assessment, disclose previous involvement in design, supply or installation and possible interests. Clarify who commissions and receives the report and its intended use. A privately commissioned assessment does not become court-appointed merely by its title.
Choose methods for the goal
Visual inspection, electrical measurements, thermography and electroluminescence answer different questions. Thermal images can locate concerns without replacing every electrical check or a reasoned diagnosis. Cell damage and shading may need different investigations.
Agree whether the whole system or samples are examined and what follows a concerning finding. Weather, operating state, access and preparation may affect measurements. Drone work and laboratory investigation are not automatically included in every assessment.
Prepare the records you already have
Plans, component information, commissioning records, previous reports and output data can help. For reduced output, the period and known changes are useful. Missing app data does not automatically prove that the system is not producing electricity.
You need not perform measurements or diagnoses to start. State available information and unresolved points. The specialist can clarify missing records and the next step; do not put passwords or confidential records into the request field.
A reasoned report rather than images alone
A useful report states the question, areas examined, procedures and conditions. Findings should identify the relevant components and explain the conclusions. Inaccessible parts, sampling and necessary further investigations are limitations to record.
For insurance, sale or a dispute, clarify report requirements beforehand. Payment, acceptance by others or a particular dispute outcome is not automatically guaranteed. Repair is also a separate commission from independent assessment.
Useful information for a clear assessment commission
The question and known records help define the assessment. Technical self-diagnosis is not required.
- Question. State the decision needed, observed issue and intended recipient.
- System. Describe known capacity, project stage and affected components.
- Records. Have available drawings, output data and previous investigations ready for later review.
- Visit. Coordinate location and known access; no personal roof or electrical tests.
Compare costs for the investigation
Price depends on the goal, system size, access, records, measurements and report. A thermal flight differs from a broader system inspection or case-specific assessment. Ask for separate preparation, investigation, analysis and additional-work items.
As a scoped example, a Swiss 2026 price list quotes CHF 656 for drone thermography and CHF 1,262 for a system inspection up to 30 kWp, excluding VAT. Conditions apply April to October with weather-dependent completion within three months; restricted flight zones and preferred dates can add charges. These are two packages from one business, not a Swiss average or the price of every assessment.
| Item | Clarify in the quote |
|---|---|
| Investigation | Whole system or samples, methods and preparation. |
| Analysis | Data comparison, reasoned findings and report. |
| Extras | Access, dismantling for tests, special dates and other specialists. |
| Total | Travel, VAT, exclusions and approval for additional work. |
Use the findings to plan the next step
Separate findings, urgency and recommendations. Some questions can be answered from records; others need further measurements or another discipline. Commission additional work with a clear goal and scope; the assessment should make that decision easier.
- Define. Define the aim, specialist field and assessment scope.
- Investigate. Assess records and agreed investigations with their limits.
- Explain. Distinguish findings, assumptions and recommendations clearly in the report.
- Decide. Commission further work with separate approval and a defined scope.
Frequently asked questions
Must I choose a measurement method?
No. Describe your goal and known observations. The specialist proposes suitable investigations and explains scope and limitations.
Is thermography a complete assessment?
Not automatically. Images, electrical measurements and reasoned assessment have different roles. The agreed question is what matters.
Are all records needed before requesting quotes?
No. State known details and missing information. Further records and useful investigations can be clarified afterwards.
Is repair included?
Only if expressly agreed. Independent assessment, repair recommendation and completed repair are different services.
Is an assessment automatically accepted by others?
That is not universally guaranteed. Clarify recipients, purpose and requirements before commissioning, particularly for insurance or disputes.
How do I clarify the independence of the assessment?
Ask about specialist experience and existing relationships with supply, installation or earlier investigations. Agree the question, investigation scope and a reasoned report. The word assessment alone establishes neither independence nor acceptance by insurers or courts.
