19.1
19
Components of PV systems
In this chapter we discuss all the components of PV systems, except PV modules that were
already treated in Chapter 15. We start with discussing maximum power point tracking in
Section 19.1, which is followed by a treatment of photovoltaic converters in Section 19.2.
Further, we we look at batteries in Section 19.3, charge controllers in Section 19.4, and
cables in Section 19.5.
Maximum power point tracking
In this section we discuss the concept of maximum power point tracking (MPPT). An MPP
tracker is never an actual component itself but always connected to a DC-DC converter in
a PV inverter or a charge controller. However, as it is a very important concept we will
discuss it here. MPPT is unique to the field of PV Systems, and hence brings a very
special application of power electronics to the field of photovoltaics. The concepts
discussed in this section are equally valid for cells, modules, and arrays, although MPPT
usually is employed at PV module/array level.
As discussed earlier, the behaviour of an illuminated solar cell can be characterized
by an I-V curve. Interconnecting several solar cells in series or in parallel merely increases
the overall voltage and/or current, but does not change the shape of the I-V curve.
Therefore, for understanding the concept of MPPT, it is sufficient to consider the I-V curve
of one solar cell. The I-V curve is dependent on the module temperature and on the
irradiance, as we will discuss in detail in Section 20.3. For example, an increasing
irradiance leads to an increased current and slightly increased voltage, as illustrated in
Figure 19.1. The same figure shows that an increasing temperature has a detrimental effect
on the voltage.
19
Components of PV systems
In this chapter we discuss all the components of PV systems, except PV modules that were
already treated in Chapter 15. We start with discussing maximum power point tracking in
Section 19.1, which is followed by a treatment of photovoltaic converters in Section 19.2.
Further, we we look at batteries in Section 19.3, charge controllers in Section 19.4, and
cables in Section 19.5.
Maximum power point tracking
In this section we discuss the concept of maximum power point tracking (MPPT). An MPP
tracker is never an actual component itself but always connected to a DC-DC converter in
a PV inverter or a charge controller. However, as it is a very important concept we will
discuss it here. MPPT is unique to the field of PV Systems, and hence brings a very
special application of power electronics to the field of photovoltaics. The concepts
discussed in this section are equally valid for cells, modules, and arrays, although MPPT
usually is employed at PV module/array level.
As discussed earlier, the behaviour of an illuminated solar cell can be characterized
by an I-V curve. Interconnecting several solar cells in series or in parallel merely increases
the overall voltage and/or current, but does not change the shape of the I-V curve.
Therefore, for understanding the concept of MPPT, it is sufficient to consider the I-V curve
of one solar cell. The I-V curve is dependent on the module temperature and on the
irradiance, as we will discuss in detail in Section 20.3. For example, an increasing
irradiance leads to an increased current and slightly increased voltage, as illustrated in
Figure 19.1. The same figure shows that an increasing temperature has a detrimental effect
on the voltage.