Types of photovoltaic plants

Off-grid PV plants

Off-grid PV plants are plants which are not connected to the grid and consist of PV modules and of a storage system which guarantees electric energy supply also when lighting is poor or when it is dark.

Complete Guide To Photovoltaic Plants
Complete Guide To Photovoltaic Plants (on photo: 52 MWp solar PV power plant in Jordan)

Since the current delivered by the PV generator is DC power, if the user plant needs AC current an inverter becomes necessary.

Such plants are advantageous from a technical and financial point of view since they can replace motor generator sets whenever the electric network is not present or whenever it is not easy to reach.

Besides, in an off-grid configuration, the PV field is over-dimensioned so that, during the insolation hours, both the load supply as well as the recharge of the storing batteries can be guaranteed with a certain safety margin taking into account the days of poor insolation.

Principle diagram of a PV plant working off-grid
Figure 1 – Principle diagram of a PV plant working off-grid

At present the most common applications are used to supply (Figure 1):

  • Pumping water equipment;
  • Radio repeaters, weather or seismic observation and data transmission stations;
  • Lightning systems;
  • Systems of signs for roads, harbors and airports;
  • Service supply in campers;
  • Advertising installations;
  • Refuges at high altitudes.

Grid-connected PV plants

Permanently grid-connected PV plants draw power from the grid during the hours when the PV generator cannot produce the energy necessary to satisfy the needs of the consumer.

On the contrary, if the PV system produces excess electric power, the surplus is put into the grid, which therefore can operate as a big accumulator: as a consequence, grid-connected systems do not need accumulator banks.

Grid-connected PV plant
Figure 2 – Grid-connected PV plant

Such plants (Figure 2) offer the advantage of distributed – instead of centralized generation: in fact, the energy produced near the consumption area has a value higher than that produced in traditional large power plants, because the transmission losses are limited and the expenses of big transport and dispatch electric systems are reduced.

In addition, the energy production in the insolation hours allows the requirements for the grid to be reduced during the day, that is when the demand is higher.

Permanently grid-connected PV plant
Figure 3 – Permanently grid-connected PV plant

Figure 3 above shows the principle diagram of a grid-connected photovoltaic plant.

Title:Photovoltaic plants – Technical Application Papers No.10 – ABB
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Complete guide to photovoltaic plants
Complete guide to photovoltaic plants

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  1. Vipin Elambilan
    Aug 26, 2018

    Thanks a lot for all the great information you share here.

  2. Fernando
    May 03, 2018

    Thanks a lot for all the great information you share here.

    Apr 25, 2017

    what is the impact of lattitude of location of installation

  4. Eugen
    Oct 20, 2015

  5. Cahyo Sumarmo
    Oct 19, 2015

    i have the same problem withdownload,already copy paste~Copy this link and open new tab in your browser. Paste it and it will work.~still don`t works?may your suggegest?

  6. Prashant
    Oct 18, 2015

    Not able to download the

    Title: Photovoltaic plants – Technical Application Papers No.10 – ABB

    After clicking the Download here , It wont start.

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