Hi Siri, I'm not sure about the System screen going red, but with regards to the shading calculation, I found that the following method best represents the SolarEdge performance under shading: You should use 100% electrical effect, and partition the module strings in a way that will define each sub-module. A sub module is the row of cells in a module that are protected under a bypass diode. In 60 cell module you usually have 3 bypass diodes, and in 72 cell modules you will have between 3 and 6 diodes (consult the datasheet or look in the PVsyst module parameters). So, this means that, for a 60 cell module for example, you will partition each module into three sub-modules, or 'strings'. See the image below for what it will look like: What you will have, in effect, is many tiny 'strings', and this mimics the ability of the SolarEdge system to manage power even on a sub-module level. Using 'Linear' shading loss is a good approximation of the SolarEdge performance, but using the above method may produce more realistic results. Note that for a traditional system, you need to partition the module strings in a size that correcponds to a whole string of modules, so you will get much larger 'rectangles' of course.