3D Shade Calculator with microinverters/many strings

Hi there,

I'm often modelling microinverter Solar PV arrays and therefore have many strings associated with each subarray. E.g. 20 module system with 2 subarrays, each with 10 strings in parallel (1 module and 1 micro per string) for a total of 20 strings.

To properly model this with the 3D Shade Calculator, would I have to create 36 uniquely placed (x,y) active surfaces? Due to the limit of 8 strings per subarray, to do this, I would have to break the main array into 3 subarrays: 2x8 strings and 1x4 strings or something similar.

For this example, is there a way to only create 2 active surfaces, each representing a subarray?

When the shading calculations are performed, do the values obtained from string 1 in subarray 1 copy into all strings of subarray 1? Based on the message that is produced when I try this (i.e. "For subarray 1, you specified 10 strings and have 1 strings in the 3D scene - Do you still wish to continue with the 3D scene values?."), this doesn't seem to be the case.

Thanks!

Hi,
Yes. You can use the 3D shade calculator to calculate an hourly (8760 hours/year) beam shading factor array for each of the two subarrays. As you suggest, create an active surface for each subarray, and assign a subarray number in the 3D shade scene properties. When you close the 3D shade calculator, ignore the messages about the number of subarrays.
Then, in SAM, for each subarray, click Edit shading and disable the Enable partial shading model option. That will make the Strings in Subarray input disappear, and SAM will model the impact of shading as a reduction in irradiance without applying the empirical partial shading model. That model is for string or central inverters where shading affects the output of the entire string.

Best regards,

Paul.