Outline: Photovoltaic. Photovoltaic Application. Photovoltaic modeling and MPPT. Power Electronics for Photovoltaic

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2 Outline: Photovoltaic Photovoltaic Application Photovoltaic modeling and MPPT Power Electronics for Photovoltaic 2

3 Photovoltaic 29.7 GW in GW in GW in Europe in GW in GW in Italy GW in Germany Italy and Germany % million households 2.2 GW China GW in USA (2011) Advantages: Pollution-free energy. Low maintenance cost (no moving/rotating parts). Long life time (> 20 years) Limitations: Ineffectiveness during the nights or low insolation periods. Partially shading problems. High initial capital cost. 3

4 Photovoltaic 4

5 PV Applications 5

6 [1] Small-scale Photovoltaic Roof-top mounting: Feed-in tarif (e.g., Germany) Own supply of electricity Problems: Partial shading Power losses Snow and ice 6

7 [2] Building-integrated Photovoltaic CIS Tower in Manchester, UK (the largest commercial solar facade in Europe) 7,244 PV modules 80 watts each 391 kw peak power Advantages: Cut-down electricity cost Large facades are already available Problems: Partial shading 7

8 [3] Large-scale Photovoltaic Waldpolenz Solar park, Leipzig, Germany (the world s largest PV farm, 2008) 52 MW peak power 153,650 PV modules 220 hectares Investment cost 130 M Advantages: No pollutants Profitable investment? Problems: High power fluctuations Maintenance (ice) Locating a fault 8

9 Photovoltaic Model I C I C I ph I D Iph ID qv nktc IC I ph I 0(e 1) D V C q(v nktc IC I ph I 0(e 1) C I C R S ) V C nkt q C I ln( ph I I 0 0 I C ) R S I C q 1.602*10 K 1.38* J/ C o K 9

10 Isc Photovoltaic Maximum power Maximum power W/m W/m Maximum power Imp Voc W/m W/m Vmp W/m Nonlinear current-voltage (I-V) characteristics 10

11 PV Direct Connection PV Module + - Load Problems: The operating point depends on the load. B Maximum power A Only one operating point leads to the maximum power. 11

12 Power Electronics in Photovoltaic Why? To track the maximum power from PV (MPPT). To convert the power to power. To control the voltage level. To interface PV with load (stand-alone or grid-connected). Power electronics converter Criteria: Reliability. Achieves MPPT. Inject high quality current, Cost abd efficiency. + PV - C2 T1 T4 T2 T5 T3 T6 To Load or Grid 12

13 Power Electronics in Photovoltaic Power Electronic converter topologies: - converter modifies the PV voltage and MPPT. Transformer to provide galvanic isolation. PV Inverters With - converter Without - converter With isolation (transformer) Without isolation With isolation (transformer) Without isolation On the LF side (grid side) On the HF side (- Converter side) 13

14 Converter Configurations: Power Electronics in Photovoltaic Centralized Technology String Technology Multi-String Technology module Technology 3-phase connection 1-phase connection 1 or 3-phase connection 1-phase connection 14

15 Power Electronics in Photovoltaic [1] Centralized Converter: (The oldest technology) Advantages: Few converters are used. Low power losses: small number of power switches. High input voltage. Disadvantages: High voltage -cables between PV and the converter. Power losses: centralized MPPT Mismatch losses among PV modules. Not flexible design 3-phase connection 15

16 Power Electronics in Photovoltaic [2] String Converter: (reduced form of Centralized converter) Advantages: Few converters are used. Low power losses. High input voltage (at sufficient number of PV modules). Allows individual MPPT. Missmatch losses are reduced (still exist). Overall efficiency is improved (> Centralized topology) Disadvantages: If the input voltage is low, - converter or transformer is required. 1-phase connection 16

17 Power Electronics in Photovoltaic [3] Multi-string Converter: (Present day technology) Advantages: Has the advantages of the two previous topologies. High input voltage. Allows individual MPPT. Higher efficieny. Flexible design. [4] Module Topology: ( Future technology) Each PV module is integrated with its inverter in single device (plug & play). 1 or 3-phase connection 1-phase connection 17

18 References Global Market Outlook for Photovolatics until 2016, EPIA, May Kjaer, S.B.; Pedersen, J.K.; Blaabjerg, F., "A review of single-phase gridconnected inverters for photovoltaic modules," Industry Applications, IEEE Transactions on, vol.41, no.5, pp.1292,1306, Sept.-Oct Edwin, F.; Weidong Xiao; Khadkikar, V., "Topology review of single phase grid-connected module integrated converters for PV applications," IECON th Annual Conference on IEEE Industrial Electronics Society, vol., no., pp.821,827, Oct