Shading from adjacent modules is often referred to as ‘inter-shading’
Shading on PV modules can significantly reduce the energy harvest and must be minimized. The PV cells are connected in long strings and if the current in one cell is reduced from shading, it affects the whole string, resulting in a much greater energy reduction than just from the shaded cell.
Setting array of modules apart reduces inter-shading but increases the total area of the solar plant and therefore ancillary costs such as land preparation or cabling. There is a trade-off between the additional revenue gained by reduced shading and the additional cost resulting from increased project footprint. Shading is quasi-inevitable around dawn and dusk because of the low sun position at that times.
Shading occurs at the lowest part of the array. In landscape installation mode, the shading will affect only one diode zone , in portrait, all three zones are impacted. Therefore, it is preferable to install the modules in landscape mode.