PV Grid Connection

Last updated on 2024-03-28 2 mins. to read

To connect a PV system to the grid, several components are required:

  1. PV Array is where solar energy is captured and converted into DC (Direct Current) electricity. The PV array consists of multiple solar panels linked together.
  2. Inverter: DC electricity from the PV array is directed to an inverter. The inverter converts DC electricity into AC (Alternating Current) electricity, which is compatible with the grid and home appliances.
  3. AC Distribution Board: AC electricity from the inverter is then routed to an AC distribution board. This component distributes the electrical power to different loads within the property and also connects to the meter.
  4. Meter:  measures the amount of electricity generated by the PV system and supplied to the grid. In many setups, this can be a smart meter that can also track electricity drawn from the grid.
  5. Grid: electricity flows from the meter to the national grid, where it is distributed to various consumers.

Each component is represented as a node in the diagram, with arrows indicating the direction of electricity flow from the PV array to the grid.

UK Compliance

In the UK, the connection and operation of photovoltaic (PV) systems and other types of electricity generation units to the grid are governed by specific compliance requirements, primarily G98 and G99, set forth by the Energy Networks Association (ENA). These requirements ensure that all generation units, regardless of size, operate safely, reliably, and efficiently within the grid infrastructure.

  1. G98:  applies to smaller-scale generators with a capacity up to and including 16A per phase, which is roughly equivalent to installations under 3.68kW (single-phase) or 11.04kW (three-phase). G98 covers the technical requirements for the connection of such microgeneration equipment to the low voltage electricity distribution networks. Most domestic PV systems fall under this category.
  2. G99: for larger installations that exceed the specifications covered by G98, G99 comes into play. It is aimed at installations that are directly connected to the distribution network or are above the threshold set by G98. G99 includes more comprehensive and stringent requirements due to the potential impact these larger installations could have on the grid. It covers aspects such as engineering recommendations, planning, and operational procedures to maintain grid stability and safety.

Both G98 and G99 include guidelines on aspects like synchronization, islanding protection, fault level contributions, and power quality. Compliance with these standards is crucial for gaining permission to connect to the grid and for the ongoing operation of PV systems, ensuring they do not adversely affect the grid's operation and other connected users.