Page 41 - Renewable Energy Devices and System with Simulations in MATLAB and ANSYS

28 Renewable Energy Devices and Systems with Simulations in MATLAB and ANSYS ®
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FIGURE 2.12 Diagram of a typical PV panel consisting of 72 cells in series.

tend to degrade more quickly, specifically in high-heat (e.g., in the desert) or high-humidity environ-
ments (e.g., tropical or seaside areas). High heat and humidity can degrade and corrode the materials
that protect the cells and degrade the PV cells themselves. Once the cells are directly exposed to the
outside environment, PV cells can degrade more rapidly [15–17].
When working with PV systems, it is important that the PV cells are properly connected to meet the
voltage and current needs of the application and that the cells are protected according to the expected
environmental conditions. Today, there are ongoing research and development efforts on fault detec-
tion and protection to improve the longevity of PV panels and, thus, the entire PV system [18–21].

2.3 CONCENTRATED PHOTOVOLTAIC POWER

The basic idea of CPV power, also called concentrator PV or concentrating PV power, is to capture
sunlight from an area that is larger than a PV cell and focus the light directly onto a small PV cell.
2
Using a concentrator, the intensity of the light (in W/m ) hitting the PV cell is significantly higher
without a concentrator, which leads to a more potential energy capture. In the 1970s, CPV systems
began to be explored and developed in the United States due to the push for energy independence
and its superior performance in terms of efficiency over all existing PV technologies. During that
time period, the PV cell cost was much higher compared to that of mirrors and reflectors. Thus,
concentrating a wide area of sunlight onto a high-cost PV cell was overall cheaper than covering the
equivalent area with PV cells [22, 23]. Today, this concept has been taken to much higher levels of
solar light concentration and higher-efficiency (but also higher-cost) PV cells [23].
Generally, CPV is divided into low-concentration PV technology that uses silicon cells and high-
concentration PV technology that utilizes larger concentration setups and higher-efficiency cells. One
example of a low-concentration PV setup uses a mirror setup to achieve approximately three suns,
or three times the normal incident light intensity, onto the PV cell. The basic concept is illustrated in
Figure 2.13, where the normal incident light either directly hits the PV cell or is reflected off the adja-
cent mirrors onto the PV cell. The concentrator systems often have tracker systems that move the face
of the CPV array to follow the sun’s movement over the day in order to optimize the output power.
For high-concentration PV systems, light is generally concentrated more than 100 times using
specialized lenses or mirrors onto high-efficiency cells. As shown in Figure 2.1, these high-effi-
ciency cells are typically multi-junction PV cells that are able to capture a wider range of sunlight
to produce more energy than normal silicon cells but come with a significantly higher fabrication