S.Faulkner Posted June 21, 2016 Share Posted June 21, 2016 Revised questionI understand that for transposition the diffuse irradiance is split into circumsolar and isotropic (and horizon) components and the circumsolar is treated like the direct irradiance in the transposition.I had previously assumed that the circumsolar component was actually subtracted from the diffuse irradiance and added to the direct irradiance, and therefore treated like direct irradiance for all the subsequent calculations. I gather from the data* that this isn't done, and that PVsyst therefore treats the circumsolar component as diffuse for all subsequent calculations (reflection and shading being affected in particular).Is that correct, and is there any particular reason for not treating circumsolar the same as direct in subsequent calculations?* In PVsyst the diffuse irradiance generally increases from horizontal to plane of array. The isotropic component decreases as a result of some being behind the array, and the circumsolar component is (generally) increased in the same way as the direct irradiance. The circumsolar component must therefore be still included in the diffuse irradiance.Diffuse on POA vs Diffuse on horizontal, Perez, colour-coded by Kn (red is high, Blue is low) Link to comment Share on other sites More sharing options...
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