Mismatch Loss Attributable to String Inhomogeneity

Mismatch loss can also be induced by unshaded modules with identical solar module characteristic curves if a string module does not yield exactly the same insolation as the result of a factor such as unequal diffuse radiation or orientation differences – in other words, in the presence of solar generator insolation inhomogeneity. This phenomenon is particularly prevalent in stacked solar generator fields (see Figures 2.37 and 2.39). The discrepancies that occur within a solar generator in such cases can range up to several percentage points (see Example 2 in Section 2.5.8). These diffuse-radiation differences of course also lead to V-I characteristic curve differences for solar modules in a string and thus to mismatch loss. In addition, cumulative characteristic curve discrepancies attributable to manufacturing tolerances can result in a disproportionate increase in aggregate mismatch loss, as noted in Section 4.4.2 based on Figure 4.43.

Such mismatch losses can be minimized by creating strings comprising modules wired in series with the same or very similar diffusion radiation characteristics (e. g. at the lower or upper edge of a solar generator) (see Figures 2.37-2.39).

Updated: August 6, 2015 — 4:11 am