G98: systems up to 3.68kW per phase
Solar Pv · Lesson 21 · Advanced
Purpose
Apply G98 on its current rating basis and notification route without converting a nominal-voltage shorthand into a universal power rule.
Learning objectives
- Identify the governing boundary
- Trace energy and measurement paths
- Apply evidence in the required sequence
- Recognise unsafe assumptions
G98 provides a simplified route for fully type-tested micro-generators operating in parallel with the public low-voltage network within its scope. The operative small-unit limit is expressed as 16 A per phase; ‘3.68 kW’ is only a familiar 230 V unity-power-factor arithmetic shorthand.
Core theory
Confirm the current G98 issue, DNO process and exact hardware/software type-test record. Follow the install-and-notify timing and documentation that apply to the site.
Aggregate all generation and storage capable of parallel export at the connection point. Several individually small devices can change the applicable route.
Type testing supports compliance evidence but does not waive wiring, protection, commissioning, notification or DNO authority.
| Term | Meaning | Symbol | Unit |
|---|---|---|---|
| G98 | ENA recommendation for in-scope fully type-tested micro-generators | Not applicable | Not applicable |
| Registered capacity | Capacity assessed under the applicable network rules | Not applicable | Not applicable |
| Connection point | Boundary at which the installation exchanges energy with the distribution network | Not applicable | Not applicable |
Assumptions: Values are supplied design inputs, not universal limits; Current DNO and product evidence will be checked.
- Relationship: For the stated simple case, P = VI.
- Calculate: P = 230 × 16 = 3680 W.
- Qualify: 3.68 kW is a derived nominal example; use the current 16 A basis and full G98 scope.
The shorthand is 3.68 kW, but compliance is not established by that number alone.
Reasonableness check: The conclusion follows the connection point, aggregate plant and declared equipment rather than a marketing label.
- Treating 3.68 kW as a timeless universal threshold
- Assessing each inverter separately instead of aggregate behavior at the connection point
- Confusing a portal reading with settlement-grade metering
Where this appears in practice
A complete PV installation coordinates mechanical support, DC design, network permission, export control, metering, inspection, testing and handover.
Knowledge check
May two small generators always be assessed independently for G98?
No. Aggregate plant and the connection arrangement must be assessed under the current DNO process.
Answer: No. Aggregate plant and the connection arrangement must be assessed under the current DNO process.
Practical exercise
Given a PV inverter and battery inverter, build an aggregate connection schedule and identify the evidence needed before choosing a route.
Summary
- Use the current rule and exact product record
- Assess the whole installation at the connection point
- Commissioning evidence is broader than successful generation
Sources and review
- Engineering Recommendation G98: Energy Networks Association; Current issue and amendment must be confirmed; Great Britain
- Engineering Recommendations G99 and G100 / Type Test Register guidance: Energy Networks Association; Current issue and Connect Direct status must be confirmed; Great Britain
- IEC 62446-1:2016: PV systems: documentation, commissioning tests and inspection: IEC; 2016 + AMD1:2018; International
- Health and safety in roof work (HSG33): HSE; Fifth edition; Great Britain
Editorial review date: 2026-08-22. Professional electrical review is pending.