A Solar KPI Audit You Can Repeat Yourself

You hire someone to check your KPIs, and they send you a number. Now you have one more number to trust.

A check is only worth something if it can be repeated. Given the same inputs, anyone who runs it again has to get the same result. That includes you, without us.

Three inputs, one number

Every KPI comes from three inputs:

• The raw data: the readings as they arrived from the portal, the meter and the weather source.
• The plant data: capacity, inverters, sensors, each with the dates it was valid.
• The rules: which hours count, which sensor, what is excluded, how it is added up.

Same raw data, same plant data, same rules: the same number. If you have all three, you can recompute any number yourself, and the result has to match.

When a rerun doesn't match

Synthetic example. The numbers are made up, the mechanics are not.

The March performance ratio, reported in April, was 83.1 %. Rerun in July, it is 82.6 %. Something has changed, and the 0.5 points split by input:

A rerun that doesn't match is not a failure, as long as you can say which input changed and by how much. It is a failure when nobody can. Then the April number and the July number are just two numbers.

Doing it yourself

What it takes to make a KPI repeatable:

1. Keep every delivery as it arrived, with the date it arrived. Never overwrite raw data.
2. Keep plant data with validity dates, and corrections as new records with a reason and a name. See When a Solar Plant Changes, Its KPIs Move.
3. Version the rules. A rule change gets a new version, and old reports keep the version they used.
4. Save each report with the versions of all three inputs, not just the PDF.
5. Rerun an old report now and then. It has to match. If it doesn't, find the input that changed.

Late data is the input that changes most often. Two Dates for Every Number shows how to keep track of it.

Why it matters for an independent check

Independence is not a promise. It is something you can test. If the checker keeps the raw data, the plant data or the rules to themselves, you are back to trusting a number. If you hold all three, you can recompute any number without them and see for yourself whether it matches.

Or let us do it

That is how we work. Your raw data stays in your own storage, as it arrived, in an open format you can query with common tools. Every number carries its origin: which delivery, which master-data state, which software version. The rules are written next to the number. You can revoke our access at any time, and the data and the rules stay with you.

Start with one plant, one month.

See also

• Who Checks the Solar KPIs Your Money Depends On?
• Two Dates for Every Number