DNO G99 Grid Connection Fast Track Guide for Solar in Great Britain

Key Takeaways

• Where an energy installation is classified as apply to connect, installers must submit an Engineering Recommendation G99 application before installing the device.
• The standard assessment window requires the DNO to respond within 45 days for low voltage energy devices and within 65 days for high voltage systems.
• Installers can utilise a fast track application process by submitting the G99 Form A1-2 for fully type-tested integrated microgeneration and storage.
• Fast track processing reduces DNO connection review to 10 days or less.
• Under statutory ESQCR Regulation 22, parallel operation requires agreeing specific requirements with the distributor and fitting equipment to prevent danger or interference.
• It is the legal responsibility of the energy device owner to ensure the DNO has granted formal authorisation before work commences.

Understanding Apply to Connect vs Fast Track Pathways

In Great Britain, connecting embedded generation to the public electricity distribution network is administered by regional Distribution Network Operators (DNOs). When an installation exceeds the microgeneration threshold of 16 amperes per phase, it is designated as apply to connect.

According to national guidance issued by the Department for Energy Security and Net Zero:

• If an energy device is classified as apply to connect, installers must submit the relevant Engineering Recommendation G99 application form (or G100 if export is limited) to the DNO before installing the device to ensure safe and effective operation of the electricity network.
• Under standard procedures, the DNO will be in touch within 45 days for low voltage energy devices and 65 days for high voltage energy devices to approve the installation or request modifications.

The G99 Fast Track Procedure: Form A1-2

To prevent administrative backlogs for standard residential and small commercial hybrid systems, the Energy Networks Association established the fast track mechanism.

Eligibility Criteria

If battery storage is being implemented with a generation device and falls under apply to connect, installers can utilise a fast track application process. This involves submitting the G99 Form A1-2 application form for connection of Fully Type Tested Integrated Microgeneration and Storage installations.

10-Day Accelerated Decision Window

The application must be submitted prior to physical installation, but it dramatically accelerates network sign-off:

• Submitting Form A1-2 reduces the connection time to 10 days or less.
• Both the solar inverter and the battery storage inverter must be registered as fully type-tested on the Energy Networks Association Type Test Register.
• If the energy device is not type tested, the DNO may require additional documentation to demonstrate that it complies with relevant engineering standards.

Statutory Grid Safety: ESQCR Regulation 21 and 22

Connecting any electrical power source in parallel with the public distribution grid is governed by primary statutory legislation under the Electricity Safety, Quality and Continuity Regulations 2002.

Statutory Regulation 22 Duties

Under Regulation 22, no person shall install or operate a source of energy in parallel with a distributor's network unless the installer:

1. Has the necessary and appropriate equipment to prevent danger or interference with that network or with the supply to consumers so far as is reasonably practicable.
2. Agrees specific requirements with the distributor who owns or operates the network.
3. Ensures the source of energy is configured to disconnect itself electrically from the parallel connection when the distributor's equipment disconnects the supply of electricity to the installation.

Switched Alternative Precautions (Regulation 21)

Where a private system is operated as a switched alternative to the mains network (such as off-grid generator changeovers), Regulation 21 requires that the installer shall ensure that the source of energy cannot operate in parallel with the network, and complies with British Standard Requirements.

Owner Responsibilities and Verification

National guidance stresses that legal compliance rests squarely with the property owner:

• Energy device owners must ensure that your installation contractor has notified the DNO of your installation.
• It is the energy device owner's responsibility to ensure that the DNO has received this notification and, in the case when the energy device is classified as apply to connect, granted authorisation before the work is carried out.