PV Shading

Not all PV installations will have ideal conditions for electricity generation. Often it is unavoidable that buildings, aerials, trees or roof dormers cast their shadows onto the PV panels.

Firstly, the good news. Shadowing is much less of an issue than many in the solar industry have believed until very recently. Figures are often given of reduction in yield ranging between 20 and even 40% due to partial shading, but these are actually worse case numbers, at a given moment and do not reflect actual yield throughout a day or over a longer season. The newly developed OptiTrac Global Peak system, developed by the world's largest manufacturer of inverters, ensures that the inverters - even in partially shaded plants - can almost completely use the energy offered by the PV modules.

Background

Every PV inverter has a so-called MPP tracker. It ensures that the PV modules are constantly operated at the point of maximum power (the Maximum Power Point or MPP). It is about "teasing" the available power completely out of the modules as the amount of light on the panels varies. In SMA inverters this job is done by the operation management system OptiTrac - which cleverly ensures maximum yields. The problem arises when individual modules of an array are shaded, causing its power curve to change significantly: It now shows several operating points (MPPs) but of different quality and therefore output. A conventional MPP tracker will normally not find these and might settle for the first "MPP" that it comes across. In such a situation the output of the system will be considerably lower than it actually should be. Please click on the animation above to see how it works.

OptiTrac Global Peak allows the inverter to use the energy supplied by the PV modules almost completely - in any circumstance. Typically 96 to 98% can be achieved compared to an unshaded array.