Direct Normal Insolation - Empirical Trough System CSP

When I change the location of the concentrating solar power plant from Boulder,CO to Dagget, CA, the Direct Normal Radiation under the "Solar Field" tab remains at 950 W/m^2. Shouldn't this number change according to the location of the plant?

The Direct Normal Radiation value on the Solar Field page for the empirical trough model is a design parameter that SAM uses to define the relationship between the solar multiple and power cycle capacity. SAM does not change the value when you change the weather file.

For guidance on choosing a value for the parameter, please see the Help topic for the Solar Field page. One approach is to run a simulation and use the time series graph on the Results page to find the maximum annual value of the "DNI-cosine effect product" variable, which you can use as the design direct normal radiation value.

In general, for locations in the U.S. Southwest, a value of 950 W/m2 is appropriate. For Southern Spain, you can use a value of 800 W/m2.

Best regards,
Paul.

Hi Paul
I 've calculated the "Irradiation at design" variable value for my location (Mazara del vallo - Italy)running a simulation and use the time series graph on the Results page to find the maximum annual value of the "DNI-cosine effect product.
the result is 475 W/m2 and I think that this value is too low for my location (37.73N ; 12.06E direct normal annual 2006kWh/m2) .
Is it possible? Sevilla , in southern Spain is 37.42N ; 5.9E direct normal annual 2089 kWh/m2 same dry bulb temperature, same elevation, alittle bit more windy (+3 m/s)
best regards
Nicola Puma

Dear Nicola,

I do not have enough information to answer your question and am not qualified to do so. You can use SAM to help evaluate the quality of your weather data, and I think your approach of comparing your data with data from other nearby or similar locations is a good start.

Best regards,
Paul.