I have noticed a large different in results from identical models run in v6.12 and v6.18. The only obvious change i can see is that: 6.12: Models used Transposition Perez Diffuse Measured 6.18: Models used Transposition Perez Diffuse Erbs, Meteonorm This leads to: 6.12: -3.0% Near Shadings: irradiance loss 6.18: -1.9% Near Shadings: irradiance loss Ultimately this leads to an increase in PR of 0.9%, is there an explanation for this change between these versions?