PV Performance Guarantees (Part 1): Page 5 of 8
Inside this Article
One of the first steps in contract negotiations is to establish some common definitions. These definitions ultimately determine the basis of measurement, which can be thought of as the hardware, software and numbers that need to be gathered in order to fulfill the performance guarantee. The most commonly used terms or concepts are specific production, performance ratio, temperature compensation and irradiance compensation.
Guidelines for a Successful Performance Guarantee
For the developer or owner:
For the financier:
For the EPC contractor:
Specific production. The specific production or specific yield of a system is a modules-to-meter performance metric. It is the ratio of energy produced by the system (MWhAC) to the nameplate rating of the modules (MWDC-STC), which is usually expressed as MWh/MW. Specific production is a good way to compare various PV technologies because it basically predicts the system output of a specific technology within a given climate. In any case, the predicted result is typically based on hourly PV simulations using known system design parameters. The actual production measurement in the field can be taken at many points throughout the system, but it is typically taken at the production meter, which is located at or near the point of common coupling or utility interconnection point.