# Simulation of a Low Concentrator Photovoltaic System Using COMSOL
## 1 Introduction
[PERSON] and [PERSON] [15] developed a mathematical model, which offers a hybrid analytical-numerical 2D geometrical representation that explains the effects of direct solar radiation on a V-trough system with geometrical and tracking parameters that are highly flexible. They found that a V-trough having two mirrors of the same width could reach a CR of 2 suns while reaching 0.61 average effective suns during the daytime, when the system remained fixed. To increase energy generation and absorption of solar radiation, coupled optical, thermal, and electrical modeling was done by [PERSON] et al. [9]. They proved that a V-trough system is suitable for elevating energy output. Carrying out a simulation is an effective way to forecast the performance of any system before it is manufactured. There are many computer simulation programs that can be used in building a physical model and then studying and analyzing its data mathematically. Figure 1: Schematic diagram of the V-trough. Here, M1 and M2 are the first and second mirrors, and \(\bar{\mathfrak{o}}\) is the inclination angle [8]. [PERSON] et al. [16] performed a simulation using FORTRAN to study the optical performance of a V-trough with a tracking system placed in different cities in Saudi Arabia. They investigated two cases of the geometrical design of a V-trough that was suggested by [PERSON] et al. [13]. They found that the overall efficiency of the design did not depend on the tracking system. This conclusion supports the elimination of a tracking system, which will decrease the cost and complexity of the whole PV system. Moreover, it was found that turbidity played an important role in system performance. [PERSON] et al. [17] performed a 3-D ray-tracing simulation of a V-trough using OptisWorks with four CRs (1.5x, 2x, 2.5x, and 3x) to estimate the optimum vertex angles of a V-trough, which were \(30^{\circ},30^{\circ},22^{\circ}\), and \(19^{\circ}\), respectively. To find the effect of mirrors on the uniformity of the solar ray distribution on the surface of a PV panel, [PERSON] et al. [18] used ray-tracing analysis, employing Monte Carlo methodology, for a tilted PV module at an angle of \(13^{\circ}\). The analysis was done in different months for two cases of concentrator: the first had one mirror attached to the PV module, and the second had two mirrors. They found that the one-mirror design gave uniform illumination for seven months, although with less concentration, while the two-mirror design did not produce uniform illumination in any month, excluding June. Increasing the width of the mirror by 2.82 times the width of the PV module assisted in minimizing the non-uniform illumination on the PV surface. Another factor that affects the efficiency of the LCPVs is the increased temperature of the PV panel, which was studied in previous work [19]. COMSOL-Multiphysics software is an advanced simulation program for modelling and simulating physics-based problems. After constructing the geometrical model of any physical system and assigning the materials used in building the model, the needed physics package is linked to investigating the physical phenomena [20]. [PERSON] and coworkers [21] developed three geometric LCPV for buildings and performed simulations for it using the ray-tracing package in COMSOL. They found that the CR changed from 1.40 to 1.53 according to the geometry. In addition, they studied the cell temperature impact on the output energy and found the highest energy generation was 177 kWh/m\({}^{2}\). [PERSON] et al. [22] studied ray tracing in building-integrated concentrating photovoltaics (BICPV) using COMSOL and discussed the effect of non-uniform incident light on the optical device of a solar cell system. [PERSON] et al. [23] improved the design of a compound parabolic concentrator (CPC) by installing a lens-wall in order to reduce the damage of irregular radiation on a normal unit of CPC. Then, they simulated the optical distribution of the design and did electrical analysis using COMSOL.