Parabolic Trough Annual Energy Flow in CSP Trough Physical

Dear Paul,

I am doing a simulation of a PT power plant without TES. I wanted to make comparisons between different amounts of Design Gross output of electricity. I have set the Fossil Fuel back-up to zero and I made changes in the value for the Design Gross output. What I expected was to get the same values for the Thermal Energy form solar field and the Thermal Energy to Power Block, but their value change when I change the Design Gross output, what I consider doesn't make sense because these values should change just If I modify the aperture area or the DNI design value.

Can you help me please with this?

Sebastian

Sorry Paul,

This simulation is performed specifying the solar field area.

Dear Sebastian,

Because the abbreviation PT could stand for power tower or parabolic trough, and because SAM has two parabolic trough models, I'm not sure which model you are using. However, I think the answer is basically the same for any of the CSP models.

If you specify too large of a solar field (too high of a solar multiple, or too high of a field aperture area), then the hourly solar field thermal output may exceed the hourly power block thermal input energy. You can look at the hourly dumped energy and the field operation fraction variables for clues that the field is oversized: High dumped thermal energy values indicating that the field is producing more energy than the power block can use, or field operation fractions (fraction of the field that is defocused) of much less than 1 for many sunlight hours indicating that the collectors are frequently defocusing in an effort to reduce the field thermal output.

In other words, the solar field area in your design is probably too high for the combination of solar resource and power block capacity.

Best regards,
Paul.