Photovoltaic system: electrical equipments selection

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Grid connected PV system ≤ 10kW (Residential)

One single phase inverter

  • Typically, a 5kW grid-connected single-phase inverter. with UOC MAX ≤ 600V. One or two strings – Isctc < 25A, IAC < 32A. In this design there is no string protection.
  • A PV main switch is necessary. When the inverter is indoors, an additional remote controlled switch at the DC cable entry point is recommended for emergencies services.
Fig. P22 – Grid connected <= 10kW

10 to 100kW grid connected PV system (Small building)

One three phase inverter with one string combiner box

  • Typically, 30kW to 60kW grid-connected inverters. UOC max is generally higher than 600V (up to 1000V), Isctc does not exceed 200A, Iac does not exceed 100A.
  • This design has more than 2 strings.
  • Reverse current protection is therefore necessary.
  • A main PV switch is required. When an inverter is inside, additional remote-controlled switch at DC cable entry point is recommended for emergencies.
Fig. P23 – 10-100kW single MPPT inverter

Multi single phase inverters design

  • Typically, 6x5 to 20x5kW grid-connected inverters.
  • The design used for residential building can be duplicated as often as necessary.
  • In that case, the DC system is very simple and the AC system is very similar to usual AC systems.
Fig. P24 – 10-100kW multi single MPPT inverter

150kW to 500kW Grid connected PV system (Large building and farm)

Three phase inverter with more than two string combiner boxes

  • Typically, 150kW to 500kW single inverter.
  • This design is very similar to the three phase inverter with one string combiner box except that it has more arrays, which requires array cable protection.
  • Istc <= 400A, IAC <= 600A.
Fig. P25 – 150-500kW single MPPT inverter with N arrays > 2