Every PV inverter has a so-called MPP tracker. It ensures that the PV modules are constantly operated at the point of maximum power (Maximum Power Point, MPP). Simply said, it is about "teasing" the available power completely out of the modules at a certain solar irradiation. In SMA inverters, this job is done by the operation management system OptiTrac - thereby ensuring maximum yields.
But if individual modules of a string are shaded, its power curve changes significantly: It now shows several operating points of different quality, which cannot all be found and used by a conventional MPP tracker. In this case, the current output of the PV plant might be considerably lower than it actually should be in terms of shadowing.
The SMA solution is called OptiTrac Global Peak: To find and use the optimal operating point of partially shaded PV plants, the proven operation management system OptiTrac has been complemented by an additional feature. It allows the inverter to use the energy offered by the PV modules almost completely - in any circumstance.
Not all PV plants have similar good conditions for electricity generation. Often it is unavoidable that buildings, antennas or roof dormers cast their shadows onto the module surface. The newly developed OptiTrac Global Peak operation management system by SMA ensures that the inverters - even in partially shaded plants - can almost completely use the energy offered by the PV modules.
The SMA inverters Sunny Boy 3000TL, 4000TL and 5000TL will be equipped as standard with OptiTrac Global Peak as of the second quarter in 2010. For older devices there will be a software update available.
The article “Made for Shade” provides you with further information on this subject.