solar CPV

Concentrated photovoltaic is a promising route to achieve high efficiency solar conversion. Concentration of sunlight increases the irradiation on panel along with its temperature. At higher temperature, the efficiency of the cells drops necessitating active cooling. However, flow of a coolant consumes pumping-power leading to reduction in net power output. These two counteracting factors lead to a two-stage optimization for designing an advection cooled concentrated photovoltaic (ACCPV) system. Here, we attempt developing a design methodology where standard numerical scheme for solving a multi-level conjugate heat problem is utilized to obtain optimal operating conditions in terms of the coolant flow rate, and the sunlight concentration ratio for a series of widely used photovoltaic materials: a-Si, m-Si, p-Si, CIGS, CdTe. For the chosen ACCPV geometry, the estimated concentration ratios are computed to be 7, 9, 9, 16 and 20 for m-Si, p-Si, CIGS, p-Si and CdTe cells, respectively. Even though the estimated values of optimal parameters depend on the choice of PV material, coolant and the geometry of the system, the methodology presented here is universally applicable for any such ACCPV system. The general intuition-higher the irradiation, better the performance-is demonstrated to be false through the present analysis.

The necessity to find new forms of renewable energy is very important and urgent nowadays. The renewable sources of energy derived from the sun are one of the promising options. The photovoltaic cells as one of renewable energy sources have been largely studied in order to obtain cheap, efficient and secure PV cells. The conversion efficiency is the most important property in the PV domain. Indium gallium nitride (InGaN) alloys offer great potential for high-efficiency photovoltaics. We present numerical simulations of GaN/InGaN heterojunction solar cells by SCAPs simulation. The calculation of characteristic parameters: short-circuit current density, open-circuit voltage, and conversion efficiency. So, these simulations study the effect of indium content and thickness in these parameters. While the maximum efficiency of a p-n GaN/InGaN heterojunction solar cell with 0.2 indium composition is 2.78%, above an indium composition of 20%, the modeled heterojunction devices do not operate as solar cells.

The photocurrent produced by a multijunction III-V cell is limited by the component cell of the union which yields the lowest photocurrent. The induced energy losses are quantified by the Spectral Radiation Matching Factor (SRMF), defined as the ratio between the energy produced by a III-V multijunction cell and the energy that could be produced if the subcells were current matched at any moment. Accurate SRMF
estimations generally require accurate measurement of solar spectrum. Another method is to measure the spectrum using three ``isotype'' cells, or single-junction cells that have the same spectral response as each of the three component cells in the multi-junction stack. That method is validated against photocurrents calculated from spectral measurements (by spectroradiometer) and broadband direct beam measurements (by pyrheliometer). Those comparisons show agreement in the results above 98% under clear-sky conditions. The difference between the two independent SRMF calculations is within 1% margin. The application of this method to the spectral measurements realized in Madrid in 2009 leads to estimate an annual current spectral mismatching of around 7%.

The photocurrent produced by a multijunction III-V cell is limited by the component cell of the union which yields the lowest photocurrent. The induced energy losses are quantified by the Spectral Radiation Matching Factor (SRMF), defined as the ratio between the energy produced by a III-V multijunction cell and the energy that could be produced if the subcells were current matched at any moment. Accurate SRMF estimations generally require accurate measurement of solar spectrum. Another method is to measure the spectrum using three ``isotype'' cells, or single-junction cells that have the same spectral response as each of the three component cells in the multi-junction stack. That method is validated against photocurrents calculated from spectral measurements (by spectroradiometer) and broadband direct beam measurements (by pyrheliometer). Those comparisons show agreement in the results above 98% under clear-sky conditions. The difference between the two independent SRMF calculations is within 1% margin. The application of this method to the spectral measurements realized in Madrid in 2009 leads to estimate an annual current spectral mismatching of around 7%.