**3. Maximum power point tracker**

*Vmpp* =*Vmpp*

*<sup>S</sup> STC Impp*

*<sup>S</sup> STC μV Impp*

Note that (5) is useful once it allows estimating the amount of available PV power only from the environmental data (*S*, *T*). All other related parameters are commonly specified on PV module datasheet. For instance, considering the KC200GT PV module, the following data‐

**Figure 4.** I-V curve from Kyocera KC200GT PV module: (a) under constant temperature and (b) under constant irradi‐

**PV specified parameter Value**

Furthermore, short circuit current (*I sc*) and open circuit voltage (*V oc*) are also important for a complete PV module characterization. They remark the points where the PV generated pow‐

*STC* 26.3 V

*STC* 7.61 A

*STC* 200 W μ*<sup>V</sup>* -0.14 V/◦C μ*<sup>A</sup>* 0.00318 A/◦C

*V mpp*

*Impp*

*Pmpp*

**Table 1.** PV module specifications on STC from Kyocera KC200GT PV module datasheet.

*STC* <sup>+</sup> *μAVmpp*

*Impp* <sup>=</sup> *<sup>S</sup>*

*STC* <sup>+</sup> (*<sup>T</sup>* <sup>−</sup>*<sup>T</sup> STC*)( *<sup>S</sup>*

*Pmpp* <sup>=</sup> *<sup>S</sup>*

94 Sustainable Energy - Recent Studies

*<sup>S</sup> STC Pmpp*

sheet specifications are found:

ance.

*STC* <sup>+</sup> (*<sup>T</sup>* <sup>−</sup>*<sup>T</sup> STC*)*μV* (3)

*STC* <sup>+</sup> (*<sup>T</sup>* <sup>−</sup>*<sup>T</sup> STC*)*μA* (4)

*STC*) + (*T* −*T STC*)<sup>2</sup>

*μV μA* (5)

For maximizing the PV conversion efficiency, the incoming sun energy must be converted to electricity with the highest efficiency, accomplished when the photovoltaic module operates on the maximum power point. Nevertheless, since this operating point is strongly affected by the solar radiation and temperature levels, it may randomly vary along the I-V plan, as illustrates Figure 7.

*IPV* =

**Figure 9.** Definition of the system operating point by the I-V and load curves intersection.

**Figure 10.** I-V and load curves intersection for defining the PV system operating point.

Evidently, modifying the load curve in accordance with the solar radiation and temperature changes is not a suitable solution, since the load is defined by the user. Nevertheless, if a dcdc converter is interposed between the PV module and the load, it is possible to control the

ate on the MPP, in this case, *MPP 2*.

*VPV*

An Optimized Maximum Power Point Tracking Method Based on PV Surface Temperature Measurement

Even when the load resistance is chosen for both curves intercept each other exactly on the MPP, it is impossible to ensure the maximum power transfer for long time intervals, once

For solving this problem, in order to maintain the system always operating on the MPP, the load curve should be modified according to solar radiation or temperature changes. For ex‐ ample, from Figure 10, if the PV generation curve is *I-V 1* and the load curve is *Load 1*, the system operating point is given by *MPP 1*. Now, considering a solar radiation and tempera‐ ture change, the generation curve comes from *I-V 1* to *I-V 2*. In this situation, keeping the same load curve (*Load 1*), the system operating point is established at *X2*, i.e., out of the MPP. However, if the load curve is modified from *Load 1* to *Load 2*, the system backs to oper‐

when solar radiation or temperature change, the MPP is relocated on the I-V plan.

*<sup>R</sup>* (6)

http://dx.doi.org/10.5772/51020

97

**Figure 7.** MPP across the I-V plan considering solar radiation and temperature changes.

Thus, in order to dynamically set the MPP as operation point for a wide range of solar radia‐ tion and temperature, specific circuits, known at the literature by Maximum Power Point Trackers (MPPT), are employed.

In this chapter the studies concerning MPPT are grouped in two categories: the first is relat‐ ed to hardware, in which the influence of the dc-dc converter and load-type on the tracking quality is investigated, and the second refers to the software, where tracking accuracy and speed are targeted.
