← Full guide: Solar Generation Lower Than Promised: Diagnostic and Evidence Checklist

Measure the shortfall before blaming the panels

Measure the shortfall before blaming the panels. Check the cause, evidence to keep, recovery steps, and escalation.

Start here

Low generation can come from weather, shading, soiling, inverter downtime, string faults, grid outages, design assumptions or a genuine equipment problem. Compare measured data with the contract and a realistic expected range.

What applies to this exact problem

Low generation can come from weather, shading, soiling, inverter downtime, string faults, grid outages, design assumptions or a genuine equipment problem. Compare measured data with the contract and a realistic expected range.

Make the comparison honest

Match the record

Daily and monthly inverter generation.

Verify current status

System size, orientation and shading conditions.

Control point

Downtime or error logs.

Check first

Sales proposal or guaranteed-performance wording.

The small dashboard

For this case, the answer can change when daily and monthly inverter generation, system size, orientation and shading conditions, downtime or error logs, sales proposal or guaranteed-performance wording. Build a dated generation-versus-downtime table. Warranty or consumer claims are stronger when the technical shortfall is isolated from ordinary environmental variation.

Proof, not promises

Keep monitoring exports, electricity bills, site photos, commissioning report and warranty documents in one folder for this case. Name files with dates and retain original PDFs where possible.

RecordUse it to verifyWhy keep it
Monitoring exportsDaily and monthly inverter generationProtects the decision if a portal, account screen or verbal explanation changes.
Electricity billsSystem size, orientation and shading conditionsSeparates a written fact from a sales statement.
Site photosDowntime or error logsCreates a dated record another reviewer can verify.
Commissioning report and warranty documentsSales proposal or guaranteed-performance wordingLets you challenge the exact field, charge, date or obligation.

From question to action

  1. Pin down the first controlling fact: daily and monthly inverter generation.
  2. Reconcile it against monitoring exports and electricity bills.
  3. Test the decision under one realistic adverse case instead of assuming the best outcome.
  4. Record dates, reference numbers and the institution responsible for the next step.
  5. Escalate only the unresolved point; do not restart the case with a vague complaint.

Stop conditions

Pause before the next irreversible step if one cloudy month is treated as proof of a defective system, the vendor refuses to provide monitoring access, a performance promise has no stated assumptions.

  • One cloudy month is treated as proof of a defective system.
  • The vendor refuses to provide monitoring access.
  • A performance promise has no stated assumptions.

Check these first

  • State the exact expected result and the exact result you have now.
  • Find the official record that owns the result and compare it with your evidence.
  • Change one thing at a time, then verify the final state before moving on.

Fix it in this order

  1. State the exact expected result and the exact result you have now.
  2. Find the official record that owns the result and compare it with your evidence.
  3. Separate hardware, installer, DISCOM/net-meter, portal, and subsidy status. They are different failure points.
  4. Record system size, module/inverter details, commissioning date, generation data, application IDs, and promised scope.
  5. Compare actual installation and generation with the signed quote, warranty, and portal/DISCOM records.
  6. Ask the responsible party for the exact pending action and owner of that action in writing.
  7. Do not close the job until safety checks, commissioning, monitoring, and applicable net-meter/subsidy records reconcile.

Build the proof pack

  • Signed quote and scope
  • Module/inverter serials and warranty
  • DISCOM/portal application IDs
  • Generation data, photos, and installer tickets

Avoid making the case harder

  • Paying the final amount before checking agreed milestones
  • Assuming low generation is automatically a bad panel
  • Treating installer completion as DISCOM/subsidy completion

How you know it is really fixed

  • The official record and your real-world result agree.
  • You have enough written evidence to prove the issue is finished if it returns later.

If it is still not fixed

  1. Installer/vendor grievance
  2. DISCOM/portal grievance route
  3. Consumer forum or other official remedy where appropriate

Official sources from the full guide

Need the complete context?

This page solves one branch. The parent guide covers the full decision, edge cases, alternatives, and related checks.

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