Nominal operating cell temperature

Nominal operating cell temperature (NOCT) is a defined set of irradiance and temperature conditions used to characterize solar cells, PV modules and PV inverters. One solution guide lists the NOCT conditions as 800 W/m2 irradiance, an Air Mass 1.5 G spectrum, 20 C, and a wind speed of 1 m/s, which give a nominal operating cell temperature of 45±2 C. These conditions are closer to real field operation than standard test conditions (STC). STC uses 1,000 W/m2 irradiance and a 25 C cell temperature. NOCT is listed with STC, PTC and normal operating conditions as one of the conditions used to rate modules. The PTC rating conditions were based on the Nominal Terrestrial Environment that defines NOCT. The difference is that the NOCT environment uses a lower irradiance of 800 W/m2. Cell temperature matters because hotter crystalline silicon cells give lower voltage and power and only slightly more current. Higher temperatures also reduce cell efficiency and lifetime. Temperature coefficients turn a difference in cell temperature into changes in a module's voltage, current and power output.

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• sentence 2: support check: partial - Values match, but the passage lists 45±2 C as a separate item and cell temperature 20 C; 'give a nominal operating cell temperature' is a mild interpretation, and 'solution guide' source is not shown.
• sentence 3: support check: partial - STC values are stated, but the passages never say NOCT conditions are closer to real field operation than STC. -->