Why does the smaller Solargenix SGX-1 SCA produce higher annual electric output than the larger EuroTrough ET150?

Hi,

In the physical trough model, a collector can be chosen from the library.

It appears that the default Solargenix SGX-1 SCA provides better performance than the EuroTrough ET150 despite it having approximately half the reflective aperture area.

The optical efficiencies at design are very similar.

Is it perhaps because the shorter SGX-1 SCA's allow finer control of the solar field in terms of focussing and defocussing SCAs during peak DNI periods?

Regards,
Jonathan

Hi Jonathan,

The issue here is similar to the one you brought up in an earlier post .

The area of the Solargenix SGX-1 collector is 470.3 m^2, compared to 817.5 m^2 for the Eurotrough ET150 collector. If you are comparing systems with the same receiver, then it would make sense to compare configurations with roughly the same rate of absorbed energy per SCA loop.

The rate of absorbed energy is roughly proportional to the area of a collector multiplied by the number of collectors in a loop. So, in this case A_ET * N_ET should roughly equal A_SGX * N_SGX. If N_SGX is set to the default value of 8 (assuming here that the default case in SAM is representative of reasonably designed system), then N_ET = 4.6. Rounding up to N_ET = 5 and solving, the results are very similar to the default case (SGX-1).

However, when N_ET = 8, the rate of absorbed energy during simulations is too high, and the system has to defocus collectors more frequently than with the same number SGX collectors. You can see this by comparing values of the field operation factor results either in the data tables or time series data viewer on the Results page.

Best regards,
Paul.