ELEC 5564 Electric Power Generation by Renewable Sources - PV Power Generation System Structure

Structure of Solar PV Systems

Outline

  • Structure of solar PV systems
    1. Solar PV Array
    2. Power inverters in solar PV systems
    3. Power converters in solar PV systems
  • State space analysis

Structure of Solar PV System

  • Solar PV generator connected to electrical loads.

Structure of Solar PV System

  • Solar PV generator (Solar PV Array) supplies electrical loads through a Power Conditioning and Control Unit.

Power Conditioning Unit

  • Power Conditioning and Control Unit functions:
    1. Interface to the power supply network.
    2. Satisfy load requirements.
    3. Protect the PV cells.
    4. Achieve maximum power generation for varying weather conditions.

Structure of Solar PV System Components

  • Components include Solar PV Generator (Solar PV Array), Electrical Loads, and a Power Conditioning & Control Unit.
  • Power Conditioning & Control Unit utilizes DC-DC converters, DC-AC inverters, and MPPT (Maximum Power Point Tracking).

Power Conditioning Unit Configurations

  • Different configurations for power conditioning:
    • Charge Regulator
    • DC-DC Converter as power conditioner
    • DC-AC (DC-DC-AC) Converter as power conditioner
    • Applications include CPV (Concentrated Photovoltaics), CDC, CL, VO, VL, VI, battery, and grid connections.

Structure of Solar PV System Types

  • System types:
    • Stand-alone.
    • Grid-connected:
      • With storage.
      • Without storage.
    • Hybrid System (+RES/none-RES).
      • Direct connection.
      • Excess generation (residential applications (FiT)).
      • With energy storage (V2G - Vehicle-to-Grid).

Structure of Stand-Alone Solar PV System

  • Consists of a Solar PV generator (Solar PV Array) supplying Electrical loads via a Power Conditioning Unit.

Example of Stand-Alone System

  • Components include Filter, Diode, DC-DC converter, DC-Bus, Battery, PV Panel, DC-DC Bi-Directional Converter, DC load, DC-DC converter, and DC-AC converter for AC load.

Structure of Grid-Connected Solar PV System

  • Consists of a Solar PV generator (Solar PV Array) connected to the AC Load via a Grid-connected inverter.
  • Also includes a DC Load.

Example of Grid-Connected System

  • Schematic diagram of grid-connected 3-phase system.

Solar PV Generator Hierarchy

  • Hierarchy: Solar cell → Module → Panel → Array
  • Voc<em>pv=Voc</em>cell×(number of cells in series)Voc<em>{pv} = Voc</em>{cell} \times (\text{number of cells in series})
  • Example: Vocpv=0.5×(36)=18VVoc_{pv} = 0.5 \times (36) = 18 V (5A)
  • Series and parallel connections of solar cells are used.
  • Voc<em>pv=Voc</em>cell×(number of cells in series)Voc<em>{pv} = Voc</em>{cell} \times (\text{number of cells in series})
  • Example: Vocpv=0.5×(18)=9VVoc_{pv} = 0.5 \times (18) = 9 V
  • Isc<em>pv=Isc</em>cell×(number of cells in parallel)Isc<em>{pv} = Isc</em>{cell} \times (\text{number of cells in parallel})
  • Example: Iscpv=5A×(2)=10AIsc_{pv} = 5A \times (2) = 10 A

Solar PV Generator Positioning

  • Positioning considerations: Tilt and Orientation.
  • Tilt angle (elevation angle): Vertical angle of solar panels.
  • Azimuth angle: Horizontal facing in relation to the Equator.
  • Solar panels should face directly into the sun to optimize output.

Solar PV Generator Arrays

  • Array configurations:
    • Series PV array.
      • The output voltage is a relative sum of the individual module voltages, but the overall current is limited to that of individual modules with the lowest irradiance.
    • Parallel PV array.
      • The PV modules in this configuration are connected in parallel to each other, which limits the voltage of the PV array to that of an individual module.
    • Series-Parallel PV array.
      • The PV modules are connected in a combination of series and parallel links, allowing for the benefits of both configurations in terms of the desired output voltage and current.
    • Honey-Comb PV array.
      • The PV modules in this configuration are connected in a hexagon shape, resembling a honeycomb architecture.
    • Total-Cross-Tied PV array.
      • The PV modules are first connected in parallel rows, and the rows are then connected in series. The voltage across each row is equal to the open-circuit voltage, VocVoc, of a single PV module, and the PV array’s output voltage is the sum of voltages across all the rows. The total current is the sum of currents generated from all PV modules in a row.