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Standards reference

ENA EREC G98 — micro-generation up to 16 A per phase

G98 is the connect-and-notify route. If your generation is fully type tested and no larger than 16 A per phase, you install it first and tell the network operator afterwards. Above that threshold, or outside the conditions below, you are in G99 and the process is very different.

Reference: ENA EREC G98 Issue 2 (2025) Updated 2 September 2026

What G98 covers

G98 sets the Great Britain technical requirements for connecting micro-generators in parallel with the public low voltage distribution network. In practice that means domestic and small commercial solar, battery storage, small wind and small CHP.

Its requirements sit on top of the European standard EN 50549-1 rather than replacing it (Clause 2.1). So a compliant product meets both: EN 50549-1 as the general standard for generating plant connected to LV networks, and G98 for what GB specifically asks on top.

The current edition is Issue 2, which came into effect on 10 March 2025, replacing Issue 1 and its amendments. It is a Distribution Code document, approved through the GB Distribution Code Review Panel.

The 16 A threshold, precisely

The number everyone knows is 16 A per phase, and the detail matters more than the number does.

Clause 2.3 sets it as the aggregate Registered Capacity of the whole micro-generating plant, not the rating of any one unit. The standard treats one electrical installation as one plant however many generating units sit inside it, and whether they are single or three phase. So two 10 A inverters at one property are not two separate G98 jobs; they are a single installation of 20 A per phase, which is over the line.

Above 16 A per phase, Clause 2.4 sends you to G99 instead.

Software-limited ratings count, if the customer cannot change them

A manufacturer may restrict a micro-generator's rating using software settings, and the restricted figure is the one that counts — but only where those settings are not accessible to the customer. That is a footnote to Clause 2.3 rather than a headline, and it is how a physically larger inverter can legitimately sit inside G98.

Batteries and EVs are in scope

This is the change people most often miss. The definition of micro-generator in Issue 2 includes electricity storage, and that expressly extends to electric vehicles capable of operating in vehicle-to-grid mode when they are exporting.

Two dates govern how much of the standard applies to storage:

  • Storage devices commissioned on or after 1 September 2022 are covered in full (Clause 2.2). Devices commissioned before that date follow G98 subject to the exclusions in Appendix 1.
  • The falling-frequency requirements in Clauses 9.4.3 and 9.4.4 apply only to storage commissioned on or after 1 March 2026 — a deadline that has now passed, so any storage commissioned today is inside them.

When G98 does not apply

Being under 16 A per phase is necessary but not sufficient. The standard carves out several cases that go to G99 regardless of size:

  • Shared supply arrangements. Clause 2.6 excludes any case where the generation serves more than one independent customer under a sharing agreement. Those are G99 applications whatever the capacity.
  • Anything not fully type tested. Clause 2.4 applies G98 only to fully type tested micro-generators, evidenced by a Micro-generator Type Test Verification Report.
  • Island operation, and brief parallel running. Clause 2.13 also excludes installations designed to run islanded, and those that parallel with the network only briefly — the standard's measure is under five minutes in a month, which covers a lot of standby sets on their monthly test.

One case looks as though it should be excluded and is not. Clause 2.5 keeps a single fully type tested unit inside G98 even where the site takes its supply at high voltage and the generation connects on the low voltage side, provided nothing else is generating on that installation.

The 28 day notification is not an ENA courtesy. Clause 1.1 ties it to the Electricity Safety, Quality and Continuity Regulations, specifically ESQCR Regulation 22(2)(c) and the exemption to it granted by the Health and Safety Executive in August 2008.

The duty falls on the installer: make the network operator aware before commissioning, or no later than 28 days after — and the standard counts the day of commissioning itself within that 28.

Two related obligations sit alongside it. Clause 1.2 puts the network operator under a legal duty to refuse a connection that does not comply with G98 and the other relevant requirements. Clause 1.3 then points at ESQCR Regulation 26, under which it can order an existing micro-generator off the network if the installation turns out to be dangerous or to be degrading supply quality for its neighbours.

Several nearby jobs? Connect-and-notify may not apply at all

This is the one that catches installers out. Clause 5.1.2 withdraws the connect-and-notify route where the same installer has commissioned, or plans to commission, other micro-generating plant in a close geographic region within 28 days either side. That work moves to the multiple premises procedure in Clause 5.2 — and Clause 5.2.1 makes it an approval first process: no connection until the DNO has approved the application and completed any enabling works of its own.

A run of domestic solar installs on one street in the same month is exactly the pattern that triggers it.

And connect-and-notify is never permission-free

Even on the single premises route the network operator has two statutory powers, not zero: it must refuse a non-compliant connection, and it can require disconnection later. Neither is discretionary.

Fully type tested means something specific

G98 works because the testing has already been done, once, by the manufacturer, for that product — not by the installer for that installation. Clause 6 covers the certification side: type test certification, compliance, and a family approach that lets a range of similar products be covered by testing a representative sample rather than every variant.

The practical consequence for an installer is that the question is not "will this pass" but "is this product on the register". ENA maintains a type test register of products verified against the standard.

The connection process

Clause 5 sets out two procedures. The single premises route (Clause 5.1) is the connect-and-notify one most people mean by G98. The multiple premises route (Clause 5.2) covers a batch of installations near one another, scheduled together — a new housing development, or a social housing retrofit — and as noted above it requires the network operator's approval before anything is connected.

Issue 2 also added a small practical step: Clause 5.1.3 requires a photograph of the cut-out to accompany a Connect Direct application. Minor, but it is new, and it is the sort of thing a job gets bounced for.

Clause 8 covers what happens around commissioning: the commissioning itself, the notification of it, notification of any subsequent changes, and notification of decommissioning. That last one is regularly forgotten — removing generation is a notifiable event too.

Appendix 2 carries a flow chart of the whole connection procedure, and Appendix 3 the documentation a micro-generator must come with.

What the standard requires technically

Clause 9 holds the general technical requirements, and they are largely about how the generator behaves when the network misbehaves:

  • Frequency withstand (9.1) and rate of change of frequency (9.2)
  • Limited frequency sensitive mode, overfrequency (9.3) — reducing output as frequency rises
  • Active power output (9.4), including the falling-frequency behaviour that now applies to storage
  • Power factor (9.5) and automatic connection (9.6)
  • Cyber security (9.7) — added by amendment in 2021 rather than in Issue 2, and a sign of where this is heading

Clause 10 covers interface protection, including loss of mains protection (10.2) — the requirement that generation stops feeding a network section that has been disconnected, which is what protects anyone working on it.

Clause 7 covers operation and safety: wiring and isolation, labelling, maintenance and routine testing, phase unbalance, voltage management units and earthing.

Where G98 meets G5 and P28

Clause 11 is titled Quality of Supply, and it is where G98 touches the rest of this site. The clause that matters most here is 11.1, harmonics and voltage fluctuation: it handles the two subjects by pointing at product standards — BS EN 61000-3-2 for harmonic current, and BS EN 61000-3-3 for voltage fluctuation and flicker, with a maximum voltage change of 4%.

Clause 11 also covers electromagnetic compatibility (11.3) and short circuit current contribution (11.4).

That product-standard route is the whole labour saving. For a type tested micro-generator, harmonics and flicker are settled once by the manufacturer's testing rather than assessed for your site. Cross into G99 and they become studies: a harmonic assessment under G5 and a voltage fluctuation assessment under P28, each worked for your installation against your specific point of connection.

That is the real cost of crossing the 16 A threshold. It is not the paperwork, it is the studies.

Where this page stops

This is an orientation, not the standard. It paraphrases and cites; it does not reproduce G98's text, tables or figures. For anything you are going to submit, work from your own copy of ENA EREC G98 Issue 2 (2025), which the Energy Networks Association publishes free.