Reducing partial shading power loss with an integrated Smart Bypass

Abstract The performance of photovoltaic (PV) systems can drop disproportionally due to partial shading of the solar panel. If no action is taken, the shading of a single cell can cause the entire power generation to come to a halt. Traditionally diode bypasses are used to solve this problem. The shaded cells are bypassed and do not interfere with the other cells. However, those bypassing diodes still create a significant voltage drop, causing additional power loss. The ideal bypass is one that does not create a voltage drop, thus apparently removing the bypassed cells from the system, with no extra power loss. In other words, the diode bypass is replaced with a switch with an on-resistance ( R on ) of 0 Ω. This paper describes the Smart Bypass, a bypass that tries to come close to this ideal bypass. At its center is a single reverse-blocking high-voltage NDMOS. The Smart Bypass senses the state of the cells and will activate the NDMOS when necessary, bypassing the failing cell or substring. It periodically samples the state of the bypassed substring to check when the bypass can be deactivated. In this paper, we will look at some power simulations comparing the performance of the Smart Bypass with the traditional diode and an ideal bypass. After elaborating on the schematics of the Smart Bypass itself, a prototype implementation in the I3T50 technology of On Semi is given. The functional results are discussed.

[1]  B. Raison,et al.  Maximizing the Power Output of Partially Shaded Photovoltaic Plants Through Optimization of the Interconnections Among Its Modules , 2012, IEEE Journal of Photovoltaics.

[2]  V. Agarwal,et al.  MATLAB-Based Modeling to Study the Effects of Partial Shading on PV Array Characteristics , 2008, IEEE Transactions on Energy Conversion.

[3]  Marcelo Gradella Villalva,et al.  Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays , 2009, IEEE Transactions on Power Electronics.

[4]  Jari Leppaaho,et al.  Operation of series‐connected silicon‐based photovoltaic modules under partial shading conditions , 2012 .

[5]  E. Karatepe,et al.  Development of a suitable model for characterizing photovoltaic arrays with shaded solar cells , 2007 .

[6]  T. Fuyuki,et al.  Analysis of multicrystalline silicon solar cells by modified 3-diode equivalent circuit model taking leakage current through periphery into consideration , 2007 .

[7]  W. Herrmann,et al.  Thermal and electrical effects caused by outdoor hot‐spot testing in associations of photovoltaic cells , 2003 .

[8]  Johan Driesen,et al.  Linking nanotechnology to gigawatts: Creating building blocks for smart PV modules , 2011 .

[9]  W. Herrmann,et al.  Hot spot investigations on PV modules-new concepts for a test standard and consequences for module design with respect to bypass diodes , 1997, Conference Record of the Twenty Sixth IEEE Photovoltaic Specialists Conference - 1997.

[10]  S. Silvestre,et al.  Effects of shadowing on photovoltaic module performance , 2008 .

[11]  Ronnie Belmans,et al.  Partial shadowing of photovoltaic arrays with different system configurations: literature review and field test results , 2003 .

[12]  J. Vanfleteren,et al.  The i-module approach: Towards improved performance and reliability of photovoltaic modules , 2011, 18th European Microelectronics & Packaging Conference.

[13]  H. J. Bergveld,et al.  Module-level DC/DC conversion for photovoltaic systems , 2011, 2011 IEEE 33rd International Telecommunications Energy Conference (INTELEC).

[14]  J. A. Gow,et al.  Development of a photovoltaic array model for use in power-electronics simulation studies , 1999 .

[15]  H. Outhred,et al.  Analysis and control of mismatch power loss in photovoltaic arrays , 1995 .