Solar Export Limits UK: How Much Can You Export to the Grid?

There is no limit on how many kWh you can export over a year. The limit is on power: how many kilowatts your system can push into the street at any one moment. Every solar or battery system connected to the mains in Great Britain has to be declared to the company that runs the local electricity network (for most of London, UK Power Networks), and which route it takes comes down to one number: 16 amps per phase.

Under it, your installer connects the system and notifies the network afterwards. Over it, an application normally has to be approved before the system is connected. That is G98 versus G99 in two sentences. Everything below is the detail that decides which side of the line you are on, and what happens if you are on the far side.

Key points

• The rule is 16 A per phase, which the engineering recommendation itself translates as 3.68 kW on a single-phase supply and 11.04 kW on three-phase.

• It is measured on the inverter's AC output, not on the size of the panel array and not on the battery's kWh.

• It is the total across everything generating at the property, not each device separately. This is what catches battery retrofits.

• Under it: G98, connect and notify within 28 days. Over it: usually G99, apply and get approval first.

• The paperwork is the installer's job, not yours. The MCS installation standard says so.

• Where the network is constrained, export limitation under G100 often lets you have the system you wanted anyway.

How much solar can I export to the grid?

People usually mean one of two things by this, and the answers are different.

Energy over time (kWh): there is no annual cap. Whatever your system generates and your home does not use can be exported, and an export tariff pays you per kWh exported.

Power at any moment (kW): this is what the network operator controls. On a G98 installation the total inverter output is within 16 A per phase, so that is the most it can ever push out. On a G99 installation the network operator may approve the full output, or approve it with an agreed export limit, which is then recorded in your connection agreement.

So when someone talks about a "3.68 kW export limit", what they usually mean is the G98 threshold. It is not a fixed export cap that applies to every home; it is the point above which the network has to approve the system first.

The number that decides everything

Engineering Recommendation G98 covers what it calls micro-generation: fully type-tested equipment with an aggregate registered capacity no greater than 16 A per phase. The document gives the conversion itself: at 230/400 V, 16 A per phase corresponds to 3.68 kW on a single-phase supply and 11.04 kW on a three-phase supply.

It is the inverter, not the panels

The figure that counts is registered capacity: the most AC power the installation can actually deliver. For an inverter-connected system, G98 defines it as the lesser of the inverter rating and the rating of the energy source.

So a 5.5 kWp array of panels on a 3.68 kW inverter is a G98 installation, because 3.68 kW is all it can ever push out. Fitting more panel capacity than inverter capacity is a normal design choice in the UK because it captures more of the weaker light through the year, and it does not change your connection route. Our guide to solar panel oversizing explains why.

The same logic runs the other way. A 5 kW inverter fed by a 2 kW array is rated at 2 kW.

For a battery, kWh is irrelevant

A common question about batteries, and the answer surprises people: the network operator does not look at how many kWh your battery holds. A 20 kWh battery on a 3 kW inverter is assessed at 3 kW, exactly like a 5 kWh battery on the same inverter. Capacity is energy; the network cares about power. Our guide to what size solar battery you need covers the difference in more detail.

Storage is treated as a form of generation, and the technical requirements in G98 and G99 apply to it. New mandatory requirements for equipment incorporating electricity storage came into force on 1 March 2026, so any battery commissioned from that date is built to them.

The trap: it is the total, not each device

Here is the part that catches most battery retrofits.

G98 is explicit that where an installation has one connection point and more than one inverter, the installation is treated as a single plant and assessed on the aggregate registered capacity. G99 applies the same principle to larger installations. The network is looking at your property, not at your equipment list.

A worked example. A house had solar fitted years ago with a 3.68 kW inverter. That sits exactly at the G98 ceiling. The owner now wants a battery. Any separate battery inverter takes the property's total above 16 A per phase, so the battery retrofit becomes a G99 application that has to be approved before the battery is connected.

The existing solar is not left out of the sum. That is why the existing inverter has to be checked before a retrofit is quoted, and it is one of the design factors covered in our guide to adding a battery to existing solar panels.

The total is worked out per connection point. A separately supplied annexe with its own meter is a different connection point and is assessed on its own.

One recent change worth knowing: since 27 August 2026, G98 has made room for plug-in solar panels of 800 W or less, without battery storage, which the householder notifies themselves. If you already have a solar or battery system, talk to your installer before adding one, because it sits on the same connection point.

G98: connect and notify

If the total stays within 16 A per phase and the equipment is fully type-tested to G98, the installation can be connected and the network told afterwards. G98 puts the duty on the installer, who must advise the network operator no later than 28 days after commissioning, counting the day of commissioning.

It is the installer's duty, not the customer's. For an installed system you should never be asked to do this yourself.

One exception: G98 only covers equipment that has been fully type-tested to it. Kit without that verification falls to G99 even if it is well under 16 A.

G99: apply first

Above 16 A per phase, the application goes in and is accepted before the system is connected. Once it is commissioned, the installer confirms what was installed, normally within 28 days. Every domestic and small commercial system falls into the smallest category, Type A, which runs from 0.8 kW up to 1 MW.

G99 also has a simplified route for small installations, called the Small Generation Installation procedure, which installers still often call the fast track. It is designed for domestic solar and battery jobs. In some cases, where output is limited to stay within 16 A per phase, the process is simpler still. Where a system is designed to keep running during a power cut, the simplified route may not apply (see the backup section below).

Timescales. The widely repeated "45 days" does not come from G99. It is one of Ofgem's guaranteed standards of performance: your network operator must provide a low voltage generation quotation within 45 working days of receiving everything it needs, with compensation payable if it is late. That is a consumer protection, and it is worth knowing you have it. Small domestic applications through the simplified route are usually turned round much faster than that.

What the network operator can come back with

For most domestic systems, approval is routine. Where it is not, it is because the local network is constrained: there is only so much a street's cables and its substation can absorb, and in parts of London a lot of solar is already connected.

The network assesses the application and issues a connection offer. It may accept the system as proposed; it may accept it with conditions, most commonly an agreed export limit; or, where the network genuinely cannot take the export, it may set out reinforcement works, or offer a flexible connection as an alternative. Connection offers are time limited, and the network operator tells you for how long.

We will not put a figure on reinforcement costs, because they are site specific and governed by a charging method that changes. If an application comes back with conditions or costs, you see them before you commit to anything.

G100: export limiting, and why it is usually good news

If the answer would otherwise be "the network cannot take that much export", there is a route that usually gets you the system you wanted.

An export limitation scheme, governed by Engineering Recommendation G100, controls the net flow of electricity at your connection point so it never exceeds an agreed maximum. The recommendation describes its purpose plainly: some customers choose to restrict the net flow at their connection point rather than wait for, or contribute to, reinforcement of the network.

In practice that means you can often install the full system, all the panels and the full battery, and agree to cap what it sends back to the street. Because a battery soaks up surplus that would otherwise be exported, an export cap often makes little practical difference to a household.

Two details worth knowing. The scheme has to bring the flow back within the agreed limit within a short response time set in the recommendation, and it has to fail safe if it loses communication. It also has to be commissioned and documented properly, and G100 applies to domestic installations in full, so this is not just a commercial tool.

A common misunderstanding: an export limit does not stop your battery charging from your own solar. Charging the battery is a flow inside your property and never crosses the connection point.

Backup power changes the route

If you want the system to keep part of the house running during a power cut, the connection route can change. G98 sends installations designed to operate in island mode to G99, and the simplified small-installation route may not apply where storage is intended to run during a grid failure.

The exact route depends on the equipment and on the network operator's process, and it should be settled before work starts. The point for you is simply that backup is part of the connection conversation, which is another reason it has to be decided at design stage rather than added later. Our guide to what keeps working in a power cut explains what backup actually gives you.

UK Power Networks: what it looks like in London

UK Power Networks runs the distribution network across London, the South East and the East of England, through three licensed businesses: London Power Networks, South Eastern Power Networks and Eastern Power Networks. Most of London and the surrounding area is in its patch. Towards the west the network operator is SSEN, and to the north, around Milton Keynes and beyond, it is National Grid Electricity Distribution.

For homes and small businesses, UK Power Networks runs an installer portal called Smart Connect for solar, batteries, EV chargers and heat pumps. Its own wording is clear about who uses it: only installers can notify on behalf of customers.

The part worth knowing as a London customer: through Smart Connect, UK Power Networks automatically approves many small solar and battery applications where the export is under 5 kW. When it announced this in June 2024, one installer reported that 80% of its applications were approved within five minutes, against two to four weeks before.

Do not misread that 5 kW figure. It does not move the G98/G99 boundary, which stays at 16 A per phase. A system above 3.68 kW on a single-phase supply still needs a G99 application. What the 5 kW threshold decides is whether that application is approved automatically rather than assessed by hand. Combined with export limiting, it is often the difference between a quick approval and a manual assessment.

Whose job is it?

Your installer's. This is not a grey area.

The MCS solar PV installation standard (MIS 3002) states that notifying the network operator under G98 or G99 shall be undertaken by the MCS contractor, and requires compliance with G98, G99 and, where export is limited, G100. UK Power Networks will only accept notifications from installers.

If a company quoting you for solar or a battery suggests the network application is something you need to sort out yourself, that tells you something useful about the company.

What happens if it is skipped? Connecting without the required approval puts the installation in breach of the Distribution Code. The network operator can ultimately require it to be disconnected, though that follows a formal process in which it writes to you setting out the problem first. The more immediate issue is simpler: nobody has checked whether the local network can safely take what your system is putting into it, which affects your neighbours' supply as much as yours.

We will not tell you it invalidates your MCS certificate, voids your insurance or blocks your export payments, because we could not find those claims supported by any primary source, and they are repeated all over the internet.

What about the Smart Export Guarantee?

Ofgem's rules for the Smart Export Guarantee do not themselves make network operator approval an eligibility condition. The tests are certification (an MCS certificate or equivalent) and a meter capable of measuring your export half-hourly. Each supplier then runs its own application process and may ask for whatever paperwork it chooses.

So the accurate version is: network approval is not an Ofgem SEG condition, but it is part of a compliant installation, and your supplier may ask to see it. If the job was done properly, you will have it either way.

EV chargers and heat pumps are a different thing

Solar and batteries are generation: they push power out. EV chargers and heat pumps are demand: they pull power in. Both have to be declared to the network operator, but under different rules and thresholds.

The practical consequence is a reassuring one: adding an EV charger does not use up your solar allowance, and adding solar does not use up your EV charger allowance. They are assessed separately.

For EV chargers and heat pumps, applications go through the Energy Networks Association's Connect Direct service. Where a home's new maximum demand falls between 60 A and 100 A, an application has to go in before installation, with a response within 10 working days. Your installer handles this too.

Frequently asked questions

Is there a limit on how much solar I can export?

Not on the total kWh over a year. The limit is on power at any moment: 16 A per phase for a G98 installation, or whatever the network operator approves under G99, which may include an agreed export limit.

Do I need DNO approval for a battery?

Every battery installation is declared to the network operator, because storage is treated as generation. Whether it is a G98 notification or a G99 application depends on the total inverter output at your property, including any existing solar.

My system is 4 kW. Does that mean G99?

It depends on what the 4 kW refers to. If it is the panel array and the inverter is 3.68 kW, it is G98. If it is the inverter's output, it is above 16 A per phase on a single-phase supply and needs G99.

How long does a G99 application take?

In UK Power Networks' area, many small domestic solar and battery applications with export under 5 kW are approved automatically. Where an application is assessed by hand, Ofgem's guaranteed standard gives the network operator 45 working days to provide a low voltage generation quotation. A realistic timeline should be part of any quote, rather than a promise of a date the installer does not control.

Can I have a bigger system if the network says no?

Often, yes, with an export limitation scheme under G100. You keep the full array and battery and agree a cap on what goes back to the street.

Does the DNO limit how much I can use myself?

No. These rules govern what crosses the boundary between your property and the network. What your own system supplies to your own home is yours.

I have three-phase. Does that change things?

It raises the G98 threshold to 11.04 kW in total, because the 16 A limit is per phase. Three-phase supplies are less common in London houses than people assume, so it is worth checking rather than assuming.

Who is my network operator?

For most of London, UK Power Networks. The Energy Networks Association publishes a postcode lookup, and your installer will confirm it from your address and meter details.

Getting it right from the start

The connection route is part of designing the system, not an afterthought. If you already have solar and are thinking about a battery, the existing inverter decides a lot, so it is the first thing to check. You can read about the systems we fit on our battery storage page, and for larger commercial roofs, where G99 and export limiting are routine, see our commercial solar pages.

Request a solar and battery quotation or call 020 3026 5032.

Facts in this article were checked against Energy Networks Association, Ofgem, MCS and UK Power Networks documentation on 19 October 2026. G99 is at Issue 2 (March 2025); G98 Issue 2 was amended in 2026 for plug-in solar; G100 is at Issue 2 Amendment 2. This is a date-sensitive subject and we review it regularly.