Green AI Energy

  CUF vs PR in Solar Plants — How to Actually Measure Performance (2026 Guide) Two engineers look at the same solar plant data. One says the plant is performing at 19%. The other says it's performing at 81%. Neither of them is wrong. This is the single most common confusion in solar plant reporting — and it usually comes down to mixing up CUF and PR. They measure completely different things, they're used by different people for different reasons, and treating them as interchangeable is how O&M reports end up contradicting PPA compliance numbers. This article breaks down what each metric actually measures, the exact formulas, why a low CUF doesn't mean a badly built plant, and how irradiance fits into all of it. Start With the Confusion, Because It's Real If you've worked in solar O&M or asset management for even a few months, you've seen this exact scenario: a monthly report shows CUF at 18% and someone in a review meeting asks why the plant is ...