# Detailed PV annual kWh potential

My goal is to calculate the annual kWh potential of PV srfs in challenging surroundings with complex shading patterns in the most detailed way possible.
I would very much like to hear how you guys do it, and what are your thoughts on this matter

These are the three ways of calculating this that I am aware of. It seems to me that they are each flawed to some extent, in their own way

1. The most simple solution is to build a simple script for modelling the PV srfs, where you can control spacing, dimensions and tilt of each row, and take resonable percentage of the sum of the annual kWh that the given srfs are receiving, but this method does not take into account that most solar panels will be severely compromised if they are just partly shaded, not to even mention the issues of just having a small part of the panels in series being shaded. Without shaded panels, this method can be okay, though.

2. The other way is to use the honeybee PVgen, but this does not allow you to play around with spacing and tilt, so I wouldnâ€™t be able to run galapagos to figure out the ideal position. It seems to be much more sensitive to the partial shading of a number of panels in a larger series, so that seems positive. On a flat surface (like on a tiltet roof) this method seems resonable.

3. The last way is to use the same kind of script as in 1. to model the srfs (maybe also divide the panel rows to individual panel srfs), and then treat each individual srf as a seperate PV generator. This allows you to run optimization on the placing of the panels, and get a more precise result than 1., since each panel will react more realistic to the shade from other panels. But this is not really how the component is intented to work, and the PV srfs will not be in series. You can do a full row in series, but then the rows will still be parallel. Thereâ€™s also a very conservative limitation on how high you can set the power output module of each pv generator srf (which you can of course override, but itâ€™s just another sign that this is not the intented use of the component.)

I would love to hear your insights on this subject!

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I simply run with a relatively fine grid to understand how many kWh each each surface receives and multiply with the panel efficiencyâ€¦this requires that the physical facade or roof implementation handles the shadows by using optimized on top of the buildin diodesâ€¦ We (SolarLab.dk) make custom BiPV facades with integrated optimized and the method described gives a pretty good approximation to what we see in real life installations and is much easier than standard PV calculation toolsâ€¦in my experience.

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Hej Anders
Tak for svar

Yes, it is definitely the simpler solution and if you analyse a largely unshaded surface I think the results are fairly accurate as well, and the PV calc tools will offer very similar results. However, when the PVs are partially shaded, the results of the PV calc tool will react stronger to this - in some cases Iâ€™ve even seen up to +40% difference in the numbers between the two methods, whereas the PV calc will show the lower number, when affected by (partial) shade.

â€¦there is also the option of using the Ladybug PhotovoltaicsSurface - does anyone perhaps have an input on that approach?