What is a G99 Application for Systems Above 50kW?

The G99 standard applies to larger renewable energy installations exceeding:

• 50kW three-phase

• Commercial, industrial, and large-scale generation

• Large battery storage and hybrid systems

These applications require a more in-depth assessment due to their potential effect on the electricity grid.

What’s Required for a G99 Application Above 50kW?

• Company name & accreditation (e.g., MCS, NICEIC certification)

• Installer and customer contact details

• Site address

System & Connection Details:

• Type of renewable system (Solar PV, wind, battery storage, CHP, etc.)

• Total generation capacity (kW/MW)

• Inverter manufacturer, model, and G99 compliance certificate

• Connection type (e.g., LV or HV, single or three-phase)

• Expected export capacity and any agreed constraints

Technical Documentation:

• Single-Line Diagram (SLD) – detailed connection diagram

• Protection settings (voltage/frequency trip settings, anti-islanding, G99 relay details)

• Fault level contribution data (how the system impacts the grid)

• Power quality study (if required by the DNO)

• Earthing & harmonic impact assessment

• DNO application form (specific to the network operator)

Application Submission & Fees:

• G99 applications over 50kW require more extensive review

• A G99 application fee applies (varies by DNO)

• The DNO review process typically takes 60-90 days

• Grid reinforcement may be required, depending on local capacity

What Happens Next?

The DNO will assess the application and:

• Approve the connection with or without conditions

• Request grid upgrades or reinforcement before approval

Once approved, installation can proceed, and a G99 commissioning report must be submitted post-installation.

At Grid Guru, we handle the entire G99 application process for large-scale renewable systems, ensuring all technical requirements and paperwork are completed for a smooth grid approval.

Need expert help with your G99 application? Contact us today!