Solar Generators with Solar Module Matrixing

In this infrequently used wiring configuration, groups comprising nMP parallel-connected solar modules and abypass diode are defined (see Section 4.3.2). The nGS of such groups are then series connected with a view to ramping up system voltage (see Figure 4.36).

The intermeshing of serial and parallel connections partly compensates for internal asymmetries. Such solar generators are not as adversely affected by the partial shading of individual modules or slight differences between module characteristic curves. If the shaded modules (which represent 25% of the total) in Figure 4.36 were fully shaded, the generator would incur only a 25% power loss. Absent cross­connections, this would comprise a solar generator with eight parallel strings for four modules wired in series. If the installation fed by this solar generator continued in operation using only the original MPP voltage VMPP of the unshaded generator, the output power of such a solar generator would decrease to practically zero.

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However, one of the main drawbacks of matrixing is that the attendant intermeshing greatly complicates the task of localizing malfunctions (e. g. module failure), which mainly manifest themselves as a voltage loss in the group with the defective module, and to a lesser extent as reduced current across the entire solar generator.

Figure 4.36 Solar generator matrixing realized by series connecting various module groups of nMP parallel – connected solar modules. Each parallel-connected module group is bypassed by a large (and cooled) bypass diode that can conduct at least 1.25 times the aggregate current of all modules. On shading of the shaded modules in the diagram, matrixing limits power to only 25%. However, installation and maintenance of such solar generators are far more cost intensive

Moreover, it is virtually impossible to monitor internal voltages continuously as this task is extremely labour intensive. To localize the defective module in the event of a malfunction, the entire generator must be shut down – which is whymatrixing is rarely used. However, it might well be possible to integrate small matrixing arrays into very large PV plants in such a way that the arrays form a string for the solar generator and are parallel connected as described in Section 4.3.3.

Updated: August 5, 2015 — 5:52 pm