News Update on Photovoltaic Energy : July – 2020

Residential photovoltaic energy storage system

This paper introduces a residential photovoltaic (PV) energy storage system, in which the PV power is controlled by a DC-DC power converter and transferred to a small battery energy storage system (BESS). For managing the power, a pattern of daily operation considering the load characteristic of the homeowner, the generation characteristic of the PV power, and the power-leveling demand of the electric utility is prescribed. The system looks up the pattern to select the operation mode, so that powers from the PV array, the batteries and the utility are utilized in a cost-effective manner. As for the control of the system, a novel control technique for the maximum power-point tracking (MPPT) of the PV array is proposed, in which the state-averaged model of the DC-DC power converter, including the dynamic model of the PV array, is derived. Accordingly, a high-performance discrete MPPT controller that tracks the maximum power point with zero-slope regulation and current-mode control is presented. With proposed arrangements on the control of the BESS and the current-to-power scaling factor setting, the DC-DC power converter is capable of combining with the BESS for performing the functions of power conditioning and active power filtering. An experimental 600 W system is implemented, and some simulation and experimental results are provided to demonstrate the effectiveness of the proposed system. [1]

Photovoltaic energy systems: Design and installation

The characteristics of solar radiation, the design of solar cells, and the installation of Si solar cell arrays for various applications are described. The discussion is limited to medium-scale photovoltaic systems, from 0.1-100 kW peak output, mounted in fixed flat plate modules, the simplest, most maintenance-free concept. Solar cell functioning principles are outlined, including the parasitic mechanisms which reduce cell efficiency. The magnitude, variations, and distribution of the global solar energy input are quantified. Consideration is given to series and parallel connected solar arrays, and to performance under a variable load. Array protection and failure detection are explored, as are integrated array power conditioning equipment comprising energy storage, voltage regulation, and ac to dc converters. Attention is also devoted to array mounting and matching solar cell systems to load. [2]

Absolute limiting efficiencies for photovoltaic energy conversion

The Detailed Balance Theory was used in the past by a number of authors to calculate the limiting efficiency of photovoltaic energy conversion. Values of 40.8% for optimum single gap devices and of 86.8% for infinite number of gaps were calculated for the maximum efficiencies of conversion of the radiation of the Sun, considered as a black body at a temperature of 6000 K. This work extends the generality of those results and introduces new refinements to the Theory: the cell absorptivity is justified to be equal to the emissivity under bias operation and under certain idealistic conditions, the optimization of the absorptivity is discussed and the concepts of solid angle and energy restriction are explained. [3]

Brazil Market Outlook for Photovoltaic Solar Energy: A Survey Study

There is great concern worldwide about increased greenhouse gas emissions and the consequences of climate change. Photovoltaic solar energy emerges as an alternative source of renewable energy with low environmental impacts. Through a bibliographical review on the subject, this paper presents an analysis of the scale insertion of this energy in Brazil, demonstrating the benefits that can be generated of this technology, impediments and future perspectives. The conclusion is that Brazil has great potential for the energy generation, collaborating to reduce the environmental impacts as a reduction of the greenhouse gases emission. The barriers to introducing photovoltaic solar energy have been lack of investment, lack of more aggressive incentive programs, technological capacity and professional training. [4]

Development of an Intelligent Electronic Module for Energy Management in Wind/Diesel or Photovoltaic/Diesel Hybrid Systems

An intelligent electronic module for managing battery power in a wind/diesel, solar/diesel or wind/solar/diesel hybrid systems was designed, fabricated and tested. It is made of five blocks mainly a power supply unit, a battery voltage monitor, a programmable interface controller, a battery charger, and a start up monitor block. A computer program inscribed on the module permits it to perform five commands. It connects dump load 1 when battery voltage attains 15V. It connects dump load 2 when battery voltage of 15V persists for some time while dump load 1 is already connected. It starts the backup generator when battery voltage is below 10.5V with no energy from the renewable source. It is also programmed to activate battery charging when only the generator is working. Based on the logical sequence designed, the module was erected on an integrated circuit using the, Advanced Routing and Editing Software, (ARES) of Proteus Professional Laboratory. [5]

Reference
[1]  Chiang, S.J., Chang, K.T. and Yen, C.Y., 1998. Residential photovoltaic energy storage system. IEEE Transactions on industrial electronics, 45(3), pp.385-394.

[2] Buresch, M., 1983. Photovoltaic energy systems: Design and installation. mgh.

[3] Araújo, G.L. and Martí, A., 1994. Absolute limiting efficiencies for photovoltaic energy conversion. Solar energy materials and solar cells, 33(2), pp.213-240.

[4] Monteiro, N.D.S.C., Monteiro, R.A.B., Mariano, J.D.A., Junior, J.U. and Romano, C.A., 2017. Brazil Market outlook for photovoltaic solar energy: a survey study. Current Journal of Applied Science and Technology, pp.1-11.

[5] Tangka, J.K., Tchakoua, P., Fotsin, H. and Fomethe, A., 2012. Development of an intelligent electronic module for energy management in wind/diesel or photovoltaic/diesel hybrid systems. Current Journal of Applied Science and Technology, pp.275-295.

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