CSP - Irradiation at design parameter

Good morning,

I have a doubt about the irradiation at design parameter, using version 2018 or 2022. The default value is 950 W/m2. When I change this value to 750 W/m2 and simulate the plant the capacity factor raises, and intuitively I expected it to fall. What coluld be the explanation to that?

Thanks for your attention.

Denise Matos.

Hi Denise,

Decreasing the design-point DNI has the effect of increasing the area of the solar field. For example, you can see that on the Physical Trough model's System Design page by comparing the field aperture value when you change the design-point DNI.

If you change the design-point DNI without changing the weather file, the larger solar field results in more energy available to the power cycle and increases the capacity factor.

For a discussion of solar multiple and reference DNI, see the System Design Help topic for the Physical Trough model: samrepo.nrelcloud.org/help/troughphysical_system_design.html .

Best regards,
Paul.