Maximum Power Current Research Articles

Optimal solar cell sorting method for high module production reliability

In photovoltaic module manufacturing processes, it is essential to achieve high production reliability of modules based on the given cells with scattered characteristics. This study aims to investigate the optimal cell sorting method to minimize the deviation of module power via simulation analysis. We consider the given solar cells to have different electrical characteristics with Gaussian distributions and ideal interconnections. We examine the resultant power distributions of modules for various cell sorting methods based on multiple cell parameters such as maximum power current, maximum power voltage, and maximum power of the cells. Our simulation shows that the average power maximum of the modules in different sorting methods has a marginal difference, and the mismatch loss by different cell characteristics is not a key factor to reduce the module reliability, but the standard deviation of the maximum powers of modules can be largely reduced by one order of magnitude if the cells are sorted out based on the reference of the average power maximum of the participated cells. Our study will provide useful guidance for cost-efficient and reliable photovoltaic modules in the manufacturing process.

Estimation of the Effective Irradiance and Bifacial Gain for PV Arrays Using the Maximum Power Current

Bifacial photovoltaic modules are able to convert the solar radiation reaching their front and rear sides, which means that more electricity can be produced using the same array area as monofacial modules with similar ratings. In some locations, the cost per power unit for such a technology has already become cost-competitive with conventional monofacial modules. The so-called effective irradiance and the bifacial gain are useful metrics, respectively, to assess the solar resource and the performance of bifacial arrays. To calculate the effective irradiance, studies previously published employ rear-side irradiance measurements, whereas to compute the bifacial gain, other works make use of monofacial modules with rating similar to those of the bifacial modules under analysis. In this article, a straightforward method is presented, allowing to calculate the effective irradiance from the maximum power current, and to calculate the bifacial gain using a power scaling relation. The proposed method was experimentally tested using an outdoor platform with a dual-axis tracking system with bifacial modules. The effective irradiance was calculated using the novel method presented nRMSE of 2.88%, relative to the results obtained using the consolidated method. The bifacial gains obtained were 6.24% and 6.69%, respectively, using the proposed and traditional calculation methods. The procedure presented in this study might be useful for the quantification of the effective irradiance and the bifacial gain for PV installations, which do not have extensive monitoring hardware.

An Experimental Investigation on Photovoltaic Array Power Output Affected by the Different Partial Shading Conditions

This paper presents an experimental investigation on photovoltaic array (PV array) power output affected by partial shading conditions (PSCs). An experiment setup of a PV array with a series configuration using 2 × 4 photovoltaic modules (PV modules) was built. The power output loss due to the shading effect on the first photovoltaic cells (PV cell) connected with bypass diodes of each photovoltaic module, installed in the PV array in the horizontal direction, was evaluated. Depending on the direction of the sun relative to the PV array configuration, the shading percentage was measured during the test and recorded the current and voltage of the PV array. The performance evaluation of the PV array configurations is referred to with respect to the values of maximum power voltage, the maximum power current, maximum power output, power output losses and fill factor (FF). The experimental results show that 44% shading of the first PV cells affects PV array power output loss by more than 80%.

A computer program for the characterization of solar cells

A quick and efficient computer program was developed in order to determine important parameters of solar cells, such as the series and shunt resistances, the ideality diode factor, the dark current, and the light current from I versus V measurements. A generalized, single-exponential model was assumed and, instead of solving nonlinear equations, we used accurate analytical approximations for the calculation of the above parameters. The program was designed to be used easily on any IBM-PC compatible computer by providing a user-friendly interface. The required input parameters, such as the open circuit voltage (Voc), short circuit current (Isc), maximum power voltage (Vm), or maximum power current (Im), were determined directly from the I–V pairs by numerical polynomial least-squares fitting, so that the user does not have to determine these parameters graphically. Therefore, our program is also compatible with a data acquisition system attached to the same computer. The program was tested with simulated data and also with real measurements for typical production silicon solar cells; in all cases, good agreement between the experimental curve and the model’s theoretical curve was achieved as determined by a high correlation factor and also by the graphical comparison displayed by the program.