Design of electrical installations integrating solar production

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HomePhotoVoltaic (PV) installationDesign of electrical installations integrating solar production

Integrating photovoltaic (PV) production into building electrical distribution systems and using it to power the building loads is becoming more common for both new and existing buildings.

However, the use of solar energy for self-consumption still rises questions. You can get the answer to some of the most common ones below and discover the recommended design rules in the pages of this section.

What does solar self-consumption mean?

Self-consumption of solar energy is the economic model in which the building uses the electricity produced by the solar panels for its own electrical needs, thus acting as both producer and consumer, or prosumer. In this model, the PV-generated energy is consumed instantaneously as it is being produced.

Solar self-consumption is becoming the preferred economic model for several reasons:

  • Self-consumption offers, or will offer soon, greater economic benefits and better control of energy bills
  • Self-consumption enables buildings to consume their own solar energy
  • Self-consumption promises greater independence from the grid and future electricity rate variations

Why self-consuming the solar energy impacts the building electrical installation? And why “exporting to the grid” solution has no impact on it?

WHEN EXPORTING TO THE GRID, YOUR PHOTOVOLTAIC SYSTEM AND YOUR BUILDING INSTALLATION ARE SEPARATE AND INDEPENDENT

When the PV production is entirely exported to the grid, the PV installation is connected to the electrical distribution network without any connection to the building electrical system. Although part of the same physical infrastructure, the PV system and the building installation are two independent and autonomous electrical units. The PV energy injected to the grid and the energy consumed by the building are measured by two independent power measurement devices. The PV installation requires a minimum of control functions, usually handled by the PV inverters, and has no impact on the building control.

WHEN SELF-CONSUMING, YOUR PV INSTALLATION IS PART OF YOUR BUILDING INSTALLATION

In this second case, the connection of the PV installation to the building electrical installation is done downward the utility meter. The PV installation is part of the building installation, and thus, its sizing, grounding system, and protection equipment are dependent on the building electrical installation. The integration of the PV installation may also require modifications in the other parts of the building electrical installation.

What is changing when integrating solar production for self-consumption?

There are three fundamental changes that occur when the choice is made to self-consume the PV energy:

  • The electrical installation is no longer supplied by a single source, but by two or more sources operating in parallel to the grid supply
  • Each local source will produce energy (or not, depending on conditions), which means that the installation has multiple operating modes, according to energy source combinations
  • The photovoltaic panels produce a direct current output and use power inverters to convert this DC output into AC
Fig. P27 – Installation integrating PV (renewables) for self-consumption

Consequently, photovoltaic self-consumption rises important technical considerations when designing the building electrical installation, such as:

  • Where to connect the photovoltaic production?
  • How to calculate the system parameters of the installation?
  • How to size a building installation with solar production?
  • How to protect a building electrical system with integrated solar production?
  • How to manage the photovoltaic system and the building loads?

The answers are in the different pages of this section.

All the technical videos included in this section

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