What Are the Grid Code G Collections of Standards?
Understand the essential technical standards that govern how distributed energy sources connect to the national electricity grid, ensuring stability and safety.
Electricity grids are intricate networks that deliver power to homes and businesses. To ensure a consistent and reliable power supply, countries establish technical rules, known as grid codes. These regulations govern how energy generators connect to and operate within the national electricity system. Grid codes manage the flow of electricity, prevent disruptions, and protect grid infrastructure and connected equipment. Standardized rules are essential to integrate diverse energy sources and avoid imbalances or widespread outages.
Understanding Grid Code G
“Grid Code G” refers to a specific collection of engineering recommendations and standards primarily utilized in the United Kingdom. This framework guides the connection of distributed generation, such as solar panels, wind turbines, and battery storage systems, to local electricity distribution networks. Its purpose is to safeguard the grid’s integrity, protect electrical equipment, and maintain high power quality and stability as smaller-scale generators integrate into the system. These recommendations are developed and regularly updated by the Energy Networks Association (ENA) and the Distribution Network Operators (DNOs) in the UK.
Key Standards: G98 and G99
Within the Grid Code G framework, two primary engineering recommendations, G98 and G99, detail requirements for connecting distributed generation. These standards differentiate based on the size and complexity of the generating system.
G98 applies to smaller generation units, typically those with an aggregate capacity up to 16 Amps per phase or 3.68 kilowatts, which includes residential solar installations. For G98-compliant equipment, a “connect and notify” procedure is followed. Installers connect pre-certified devices and then inform the Distribution Network Operator (DNO) within 28 days.
G99 governs larger or more complex generation systems, typically exceeding 16 Amps per phase or 3.68 kilowatts. This standard applies to commercial solar projects, larger battery storage systems, or substantial wind turbines. Compliance with G99 involves stringent requirements, including detailed application processes and specific technical performance criteria. These larger systems have a greater potential to impact grid stability, necessitating comprehensive checks and extensive testing and commissioning before connection.
Meeting Grid Code Requirements for Connection
Achieving compliance with Grid Code G, through either G98 or G99, requires adhering to specific technical and administrative mandates. Equipment intended for connection must be “Fully Type Tested” and certified to meet the standards outlined in the relevant engineering recommendation. Installers are responsible for ensuring their system designs and installations satisfy detailed technical specifications, including voltage limits, frequency response capabilities, and fault ride-through performance.
Compliance involves providing comprehensive documentation to the Distribution Network Operator (DNO). This documentation includes equipment datasheets, detailed installation plans, and test reports demonstrating the system meets all necessary technical criteria. The installer ensures the system is correctly implemented according to the chosen standard. The DNO reviews and approves the connection based on this demonstrated compliance. This structured approach helps integrate distributed generation safely and effectively into the electricity network.