Heliostat optimization wizard for Southern hemisphere

Hi all,

I'm experimenting with the Power Tower Circular Field Optimization Wizard. At present, whether I select a Location in the Northern (positive latitude) or Southern (negative latitude) hemisphere, the field is dominated by Heliostats at the 0.0 position.

Could anyone clarify whether "up" on this diagram genuinely corresponds to North (as opposed to, perhaps, "towards the equator") and, if so, whether the heliostat arrangement in both hemispheres should really be the same?

I've read elsewhere on the forum that, "For the PV Component model (and the CSP and solar water heating models), an azimuth angle of 0 degrees represents an array (or collector) facing the equator in both the Northern and Southern hemispheres." but I can't find anything explicit in the documentation, so would like to clarify if possible.

Thanks in advance!

Hi Joe,

The small arrow in the top left corner of the field layout diagram for the power tower models with a circular field indicates the direction of the equator, regardless of whether the latitude in the weather file is in the northern or southern hemisphere.

For a rectangular field, the arrow in the top left corner is replaced by "North ^" indicating that North is toward the top of the diagram.

As for the azimuth angle input for the other solar models, the different models use different conventions, so please refer to the notes next to the input variable and in the Help system for a description.

Best regards,
Paul.

Hello Paul,

sorry for reviving this rather old thread, but I came across
a similiar question.

I made some calculations to cross check the SAM results with another
tool using a singular heliostat with rectangular coordinates.

Two locations at latitude +30 and -30 were examined,
both with a single heliostat being 500 m north or south
of the tower, according to the "^north" indicator.

Coordinates were

X = 500 ("North")
Y = 0

or

X = -500 ("South")
Y = 0

In both cased the better heliostat was on the
northern side (X=500) of the tower, which should
only be true for the northern hemisphere.

So to me the little north arrow seems kind of pointing
away from or the equator?!?

Can someone reproduce this behavior?

Kind regards,
Joe

No ideas on this issue?

Hi Joe,

The direction indicator in the x-y layout diagram for the power tower heliostat field is incorrect. It should be the same as the indicator in the radial layout diagram: The bottom of your screen (or the negative y direction in the diagram) is in the direction of the equator for both layouts in both the northern and southern hemisphere.

The power tower optimization algorithm (DELSOL) treats the heliostat as if it is in the northern hemisphere, regardless of the system's actual location. It bases its calculations on the absolute value of the latitude value in the weather file.

Best regards,
Paul.

Hello Paul,

thanks for you reply.

Kind regards,
Joe.