Parasitic power solar field HTF pump electrical power usage

Hi Paul and team

Simple question about the Parasitic power solar field HTF pump electrical power usage. I have had a look through the forum, the help file and the physical trough report. I am battling to find how this parasitic demand is calculated. In my results, the value rarely exceeds 1.3 MWe, which is way too low. Most plants I have seen in SA have installed capacities of around 3x 2 MW or more.

In the Parasitics inputs, the only parameters we can change is the "Required pumping power for HTF through power block" and the "Required pumping power for HTF through storage" (HTF flow to and from the TES and power block, according to your explanation at this post: sam.nrel.gov/node/74810 ), but nowhere is there any input that changes the "Parasitic power solar field HTF pump", nor any indication of how this is calculated in the help file or report.

Could you please provide an indication/reference as to how this is calculated? The problem is that my Net power outputs are too high relative to the Gross power, when I compare it with measured data for a reference plant I am modelling.

Thanks
Frank

Hi Frank,

The parasitic solar field HTF pumping power calculation is described in Section 2.5 of the Technical Manual for the SAM Physical Trough Model, specifically, Equation 2.114 on Page 50.

The solar field pumping power is calculated as part of the solar field model, so its value in a given time step depends on the operating conditions of the field. The two inputs that directly affect its value are the minimum and maximum "single loop flow rate" on the Solar Field input page. Obviously, those parameters affect other parts of the model, so you should not change them with the sole purpose of adjusting the parasitic loss value.

Best regards,
Paul.