Modules from different manufacturers often have very different operating characteristics and dissimilar modules should not be used in the same series string. Likewise, mixed orientations of the same module will have dissimilar operating characteristics. But what if a site’s circumstance requires two different orientations? If half of an array faces east and the other half west, isolate the modules from each plane into separate series strings. Then use multiple inverters or an inverter that can track multiple maximum power points (MPPTs), like Magnetek’s Aurora inverter. Some grid-tie inverters with only one MPPT may work fine with non-optimal module configurations, but the exact impact is inverter-specific. For example, Fronius says its inverter can handle multiple PV orientations with a loss of 1% or less. But SMA America recommends keeping modules in the same plane for their inverters—no variations, period. So if working with mixed module orientations, and a single MPPT inverter is desired, make sure the inverter you are considering will handle the orientations you want.