How to check whether your production guarantee was met

The short answer

To check whether your production guarantee was met, compare your system's actual metered output for the true-up period against the guaranteed amount in your lease or PPA, after adjusting for any surplus carried over from the last period. If actual output is lower, the difference is your shortfall.

Step by step

1. Find three numbers in your own agreement: the annual guaranteed production (kWh), the true-up interval (many SunPower-era leases use 24 months), and the per-kWh rate used to compute a credit. GuaranteeCheck does not read your contract for you, so these come from your copy.
2. Pin down the period. Work out the start and end dates of the true-up period you are checking. For Sunrun's BrightBuy with Protection Plus agreement, the research points to each in-service anniversary.
3. Get your production for exactly that period. Enphase systems can be connected through Enphase's own login. For SolarEdge, the research found monitoring-portal admin access is often a problem for orphaned systems, because the original installer usually held the account. A CSV export or manual entry is the fallback.
4. Scale the guarantee to the period. Multiply the annual guarantee by the interval in months divided by 12.
5. Subtract actual production and any carried-over surplus. If the result is above zero, that is your shortfall in kWh. Multiply by your per-kWh rate for the dollar figure.

The full formula, including the optional degradation adjustment, is on the methodology page. A hypothetical worked example is in the true-up explainer.

What if the answer is "nothing owed"?

That is the most common result. Our research found that most systems in most periods show no shortfall, and any surplus carries forward to help the next period. A no-shortfall result is still useful to know.

What if there is a shortfall?

Then you can write to your servicer yourself. See the servicer pages for SunStrong, Sunrun and Renewbrook. GuaranteeCheck can draft the letter, and you review, sign and send it yourself.

Want the math run for you? See how the free diagnostic works, or see pricing. Common questions are answered on the FAQ.