Hi Paul,
Thank you for your answer. The library files were helpful in isolating the factors leading to the discrepancy.
I have a follow-up, more general question regarding differences between versions. I went through the
SAM Release Notes
to try to better understand the results I'm getting, but I would like a higher level of detail, if possible. Was there any modification to the calculation model/energy balance between versions 2017.1.17 and 2022.11.21 that would explain a higher yield in the 2022 version for the exact same inputs? Between 2019.11.11 and 2022.11.21?
("Fix issue when using GHI and DHI or POA options for irradiance data from weather file." from the release notes could be relevant as we do use GHI and DHI option).
Additional details:
{To recap and clarify, I built the open source version of SAM from the current patch branch (so version 2022.11.21). A colleague had built the open source versions of SAM consistent with 2017.1.17 and 2019.11.11 for an earlier iteration of our project. In all builds, the open source version was modified identically, allowing the additional input of roof surface temperature and using it instead of the ambient temperature to estimate the back of the panel temperature. Data from different roofing configurations (e.g. white roofs, green roofs, black roofs) is used and compared to investigate the effect of this roof choice on the PV yield. Consequently, as expected, a white roof configuration, for instance, leads to a higher yield. The current issue is that the results obtained with previous modifications (2017 and 2019) report a higher percentage difference between white roofs and black roofs, for example.
So basically, the sensitivity of the yield to the back of the panel temperature seems to have decreased. I would like to know what changes have been implemented to the energy balance or yield calculation (perhaps transmission efficiencies?) so that this is explainable. Note that I have also tried running the official SAM versions for the same inputs (2017 and 2022) and the 2021 version had a higher yield even without any modification from our side.}
Thank you for your valuable input.
All the best,
Lina