Path-Q Solar
What production evidence should I collect before disputing an installer performance guarantee?
Answer
Collect the signed guarantee and its calculation method, commissioning date, production and availability records, weather or irradiance data, outage and maintenance logs, utility or curtailment records, system changes, and communications with the installer. Recalculate the claimed result using the contract's defined period, exclusions, degradation assumptions, and measurement boundary before disputing it.
Key points
- Preserve original monitoring exports rather than only screenshots or monthly summaries.
- Separate system production from exported energy, self-consumption, battery charging, and utility-meter totals.
- Document shading, snow, soiling, outages, grid limits, and any owner-caused or uncontrollable exclusions.
- Use the guarantee's notice procedure, deadlines, and dispute process.
What it depends on
- The exact guarantee language and baseline
- The defined production measurement point
- Allowed weather, outage, degradation, and curtailment adjustments
- Complete and reliable monitoring data
Risks and trade-offs
- A production shortfall may result from data loss or a meter boundary rather than inadequate generation.
- A guarantee may be an energy estimate, a performance ratio, or a monetary remedy with different proof requirements.
- Missing contractual notice deadlines can weaken a claim.
Information you may need
- Signed contract, guarantee, amendments, and commissioning documents
- Time-series production, availability, and alarm data
- Weather, irradiance, outage, curtailment, and maintenance records
- Installer responses and the contract's notice requirements
Your next step
What to do next
Build a contract-based production reconciliation and send the installer a dated evidence package identifying the calculation, shortfall, and requested remedy.
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