**1. Introduction**

On the last decades, distributed generation (DG) systems based on photovoltaic (PV) gener‐ ation are slowly been introduced to the world energy matrix, in which some important as‐ pects as political incentive, cost reduction, electricity rising demand, improvements on PV materials and increasing on power converters efficiency have contributed to the present sce‐ nario [1-3].

From the power processing point of view, high efficiency conversion, by itself, cannot en‐ sure the optimized power flow, since the PV output voltage and current are strongly de‐ pendent on environmental conditions, i.e., solar radiation and temperature; however, on the literature, many works bring solutions to maximize the photovoltaic output power, employ‐ ing specific circuits denominated by Maximum Power Point Trackers (MPPT) [4-8]. In most applications, the MPPT is a simple dc-dc converter interposed between the photovoltaic modules and the load, and its control is achieved through a tracking algorithm.

The studies on the MPPT area are normally grouped in two categories: the first one relates to the dc-dc converter topology optimization, focusing on methods to determine a suitable dc-dc converter for operating as MPPT [9]; and the second one refers to the maximum pow‐ er point tracking algorithm, responsible for properly controlling the dc-dc converter in order to establish the system operating point as close as possible to the Maximum Power Point (MPP). Therefore, an *efficient* MPPT system need to be composed by the integration of an ad‐ equate dc-dc converter (hardware) and proper tracking algorithm (software), resulting in some desired aspects:


© 2012 Coelho and Martins; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Coelho and Martins; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The most popular algorithms employed in PV tracking systems [10-18] - Constant Voltage, Perturb and Observe (P&O) and Incremental Conductance (IncCond) – are extensively ex‐ plored by specialized literature, nevertheless, since fast tracking response and accuracy con‐ flict one from other, the mentioned tracking methods cannot satisfy, simultaneously, both of them. In place of the traditional and spread methods, some authors have proposed complex MPPT algorithms, based on fuzzy logic and neural network, in order to accomplish fast tracking response and accuracy in a single system. These proposals, nevertheless, present some disadvantageous: needed for high processing capacity, complexity, cost elevation and, in some cases, employment of extra sensors.

In this chapter, PV maximum power point tracking systems are analyzed under two distinct points of view: firstly, the influence of the dc-dc converter on the tracking quality is account‐ ed. In this study, the effect of solar radiation, temperature and load variations are consid‐ ered, and the tracking performance of Buck, Boost, Buck-Boost, Cuk, SEPIC and Zeta converters are compared. Secondly, a new tracking algorithm, based on the PV surface tem‐ perature, is introduced. The advantages concerning the proposed method come from the simplicity, low cost, analogue or digital implementation, fast tracking response, accuracy and no oscillation around the MPP on steady state.

In order to achieve the main chapter topics, a brief revision of PV generation is highlighted in next section.

**Figure 1.** PV array composed by an arrangement of PV modules and PV module composed by an arrangement of PV

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

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

91

The Standard Test Conditions (STC) refers to the conditions under which PV modules are tested in laboratory. STC defines the values of irradiance, temperature and air mass index, in which the manufactures feature the PV devices, permitting to compare their performance

The Sun energy reaches to the Earth through electromagnetic waves, resulting in an irradi‐

mospheric effects – scattering, absorption and reflection -, the incoming irradiance is

The process of scattering occurs when small particles and gas molecules diffuse the radia‐ tion in random directions, while absorption is defined as a process in which the solar radia‐ tion is retained by atmosphere substances and converted into heat. In addition, part of the total solar radiation is redirected back to the space by reflection and part, termed by direct

on its outer atmosphere. However, due to at‐

cells.

*2.1.1. Standard Test Condition*

and efficiency conversion.

ance (or solar radiation) of about 1366 W/m2

modified before reaching the Earth's surface [20].

*2.1.2. Irradiance*
