G99 applies to solar PV systems above the G98 notification threshold, including most commercial installations. The connection applicant submits a G99 application to the local Distribution Network Operator (DNO) before installation, including technical details of proposed generation capacity, inverter specifications, and protection settings. DNOs respond within defined timescales, though delays occur for larger systems in constrained network areas.
For larger commercial solar PV systems, G99 applications may require detailed protection studies, dedicated export limiting equipment, or network reinforcement contributions. Structural engineering documentation including a signed Solar Surveys structural report is typically requested by lenders and project sponsors as part of the due diligence pack alongside G99 documentation.