Hi there, Just a question regarding the calculation of the 'transmissivity' value for use of the Solar Radiation tool. So far I have been using the direct beam radiation divided by the extraterrestrial radiation corrected for the solar zenith angle at the time, however all the values come out far too big. Has anyone had success with a particular method of calculation or chosen a particular hour (for example, using the radiation at 12 due to the smallest zenith angle)? Thank you in advance for any replies, Jess
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