OwlIf your solar system isn't producing what was promised, a production guarantee report is the document that turns a complaint into a claim. It's structured evidence — your measured production, your contract's guaranteed production, the methodology connecting both, and the dollar shortfall that results.
But before you can produce or use a report like this, you need to understand your solar contract's production guarantee and the four clauses that determine whether your claim is collectible. Most homeowners haven't read these clauses carefully — and that's how installlers stay a step ahead.
Why Your Solar Contract Has Four Clauses That Matter
Production guarantees look simple on the surface: "we guarantee your system will produce X kWh per year." But four underlying clauses determine whether that promise means what you think it means:
- The guarantee number itself
- How production will be measured
- What exclusions apply
- The claim window
Each clause is a potential point of dispute. Understanding them before a problem arises — and again before filing a claim — is what separates homeowners who collect from those who don't.
Clause 1: The Guarantee Number
What it is: the kWh number your installer is promising
The guarantee number is the specific production promise. It might be expressed as a fixed kWh/year ("12,500 kWh in year 1"), a percentage of the original estimate ("95% of projected production"), or a degradation curve ("year 1: 13,000 kWh, reducing 0.5% per year").
The guarantee number is different from your installer's original sales pitch. A salesperson may have said "your system will produce about 14,000 kWh/year." Your contract might guarantee 12,500 kWh/year — a 10.7% lower bar. Both numbers appear in your paperwork; only the contract number is enforceable.
For context on how guarantees should work: SEIA's model production guarantee contract defines industry best practices for this clause.
Clause 2: How Production Will Be Measured
What it is: the data source and methodology that governs the claim
Some contracts specify the installer's monitoring portal as the sole measurement source ("production as measured by the SolarEdge monitoring portal"). Others allow independent measurement. This clause matters enormously if there's ever a dispute about the data.
Even if your contract limits you to the installer's data source, an independent measurement serves a critical function: it gives you a comparison point. If the installer's portal shows 12,500 kWh but an independent measurement shows 12,100 kWh, that divergence is itself evidence of a data integrity issue worth investigating.
Also look for whether the contract requires weather adjustment. "Production shall be compared to expected production adjusted for actual meteorological conditions" is a strong clause that protects you from weather-based dismissals. "Production shall equal X kWh regardless of weather" is an unusually strong guarantee that few installers offer.
Clause 3: Exclusions
What it is: the conditions under which the installer is not responsible for a shortfall
Exclusions are where production guarantees lose teeth. Common exclusion categories include: weather years that fall below the TMY baseline, system downtime caused by events outside the installer's control, grid outages, homeowner modifications to the system, and shade growth from trees.
Real-world impact: a well-drafted weather exclusion might say "if actual horizontal irradiance for the year falls more than 15% below TMY baseline for the system's location, the guaranteed production shall be proportionally adjusted." That's measurable and fair. A poorly drafted exclusion might say "guarantee is void in years with unusually poor weather conditions," which the installer can claim applies whenever convenient.
The existence of exclusions doesn't make a guarantee worthless — but it means you need to verify that your situation doesn't fall into an exclusion before filing. Weather adjustment handles most of this: if you show the shortfall persists even after accounting for actual weather, the weather exclusion doesn't apply.
Clause 4: The Claim Window
What it is: the deadline for filing your claim
Most contracts require you to file a production shortfall claim within a specified time after the measurement period ends. Common windows: 90 days after the end of the calendar year, 6 months after the measurement period, or "within the warranty period" (vague and worth clarifying).
Missing the claim window is one of the most common ways legitimate claims are waived. Set a calendar reminder for two months before your claim window closes each year. If you're not sure what your window is, err on the side of filing early.
For the full guide on timing and claim mechanics: How to File a Production Shortfall Claim.
Contract Red Flags Worth Knowing
Beyond the four critical clauses, several contract provisions significantly limit your practical ability to collect on a production guarantee:
- "At installer's sole discretion" resolution: If the contract lets the installer choose whether to pay cash or provide a service visit, they will always choose the service visit — which may or may not actually improve production.
- Capped damages: "Installer's liability shall not exceed one year's production value" means a multi-year underperformance is limited to a single year's remedy.
- Mandatory arbitration with specific rules: Arbitration is not necessarily bad, but arbitration that limits discovery or requires you to pay half the arbitrator's fees can make small claims not worth pursuing.
- Transfer restrictions: Some contracts specify the production guarantee doesn't transfer to a new homeowner. If you sell your home, the new buyer may have no recourse even if the underperformance started before the sale.
None of these are automatic deal-breakers, but they're worth knowing when you're evaluating a claim. The FTC's consumer protection guidance on home improvement contracts provides useful context on what's enforceable.
OwlWatt produces an independent claim-ready report — start a 30-day trial
Connect your Enphase system and OwlWatt tracks your production against your contract's guarantee. When you need a report, download it and send it to your installer. We don't draft or sign your contract — we just measure against it, independently of your installer and your inverter vendor.
Start a 30-day free trialWhat a Solar Production Guarantee Report Contains
A production guarantee report is a structured evidence document. Here's what a complete report includes:
Standard production guarantee report contents
- System details — address, system size (kW), installation date, inverter type, contract date
- Contract guarantee — the exact number from your contract, the measurement period, and the claim clause reference
- Measured production data — monthly production totals for the claim period, from your monitoring system, with the data source identified
- Weather-adjusted expected production — the irradiance data source (NREL/NOAA), the adjustment calculation, and the resulting adjusted baseline
- Shortfall calculation — kWh gap, dollar value at your applicable rate, and the methodology
- Date and methodology statement — when the report was generated and who generated it
The report is something you produce and send to your installer — it's not something the installer generates for you. (An installer-generated shortfall report would be an obvious conflict of interest.) The value of an independent report — from a service with no financial relationship to your installer — is that neither party can credibly claim the numbers were produced by someone with a stake in the outcome.
What If Your Contract Doesn't Have a Production Guarantee?
If you've read your contract and can't find a production guarantee, you may have only a workmanship warranty and equipment warranties — which are different instruments. Here's what each covers:
- Workmanship warranty: Covers installation defects — wiring errors, roof penetration failures, mounting issues. Typically 1–10 years.
- Equipment warranty: Covers hardware failures — panel defects, inverter failures, optimizer failures. These are manufacturer warranties passed through by your installer.
- Production guarantee: Covers the output of the whole system over time — the promised kWh number. This is the installer's performance promise.
If you don't have a production guarantee, equipment warranty claims are still worth pursuing for failed components. And consumer protection law may provide remedies if your installer made specific production promises in sales materials even without a written guarantee. See: What a Production Guarantee Actually Promises.
Related Guides
- Solar Producing Less Than Expected? Here's How to Prove It.
- How to File a Production Shortfall Claim
- Weather-Adjusted Solar Production
- Solar Underperforming? Here's Who to Actually Call
Frequently Asked Questions
What's the difference between a production estimate and a production guarantee?
An estimate is a projection — what the installer thinks your system will produce. A guarantee is a contractual promise — what the installer is legally obligated to deliver. Many homeowners have only an estimate, not a guarantee. Check your contract carefully: only the guarantee is enforceable as a contract term.
What does a solar production guarantee report actually contain?
A production guarantee report documents your measured production over a defined period, compares it to the guaranteed production from your contract, applies any required weather adjustment, calculates the shortfall in kWh and dollars, and documents the methodology. It's the structured evidence package you send to your installer to support a production shortfall claim.
What if my contract doesn't have a production guarantee?
If your contract lacks a specific production guarantee, you may still have remedies under your workmanship warranty (installation defects), equipment warranties (hardware failures), and your state's consumer protection laws. Some states impose implied warranties of merchantability on home improvement contractors. A consumer protection attorney in your state can advise on what's enforceable without a written guarantee.
Can my installer refuse to accept an independent production report?
An installer can dispute the methodology in your report, but they can't simply ignore documented evidence. If your report's numbers are based on transparent raw data sources and a documented weather adjustment methodology, the burden shifts to the installer to provide a counter-calculation. Refusal to engage itself becomes part of your record for a licensing board complaint or legal escalation.
Does OwlWatt draft or negotiate my contract?
No. OwlWatt does not draft or sign your solar contract — that's between you and your installer. We measure your system's production against your existing contract's guarantee number. We give you the evidence; you own what you do with it.
Know where you stand against your guarantee
OwlWatt tracks your Enphase production against your contract's guarantee, weather-adjusts automatically, and generates a claim-ready report whenever you need one. Independent of your installer and your equipment vendor. Subscription from homeowners only.