Modern homes can contain far more electrical equipment than they once did.
A property may have:
- solar PV
- battery storage
- an EV charger
- a heat pump
- electric hot water
- backup power
But all of that equipment still connects through one electricity supply.
That means the local electricity network may need to consider both:
- how much power the home can take from the grid
- how much power it can send back
Your home can be capable of using, generating or storing more power than the local network is prepared to let cross the grid connection.
And that is the key idea behind DNO import and export limits.
What Is a DNO?
DNO stands for Distribution Network Operator.
The DNO owns and operates the local electricity network that delivers power to homes and businesses.
That is different from your electricity supplier.
Your supplier:
- bills you
- sells you electricity
- may pay you for exported electricity
Your DNO:
- manages the local electricity network
- assesses generation and storage connections
- manages import and export capacity
- maintains the cables, substations and transformers supplying your area
Your electricity supplier sells you energy. Your DNO manages the network that carries it.
Why Does the DNO Care About Your Home?
Traditionally, most homes mainly consumed electricity.
Modern homes can now both consume and generate significant amounts of power.
A property may:
- draw heavily from the grid while charging an EV
- draw additional power for a heat pump
- charge a battery
- generate electricity from solar
- export from a battery
- send surplus solar back to the grid
All of that changes how electricity flows through the local network.
The DNO therefore needs to make sure the connection remains within safe and acceptable limits.
The Grid Connection Is a Two-Way Boundary
- Import
- Electricity flowing from the grid into the home.
- Export
- Electricity flowing from the home back into the grid.
It helps to think of the grid connection as a boundary between your property and the local electricity network.
Power can move in either direction. These two directions can have different limits.
Import and export are two different directions through the same grid connection, and they do not always have the same limit.
Maximum Import Capacity and Maximum Export Capacity
- MIC — Maximum Import Capacity
- How much electrical power the property is permitted or designed to take from the network.
- MEC — Maximum Export Capacity
- How much power the property is permitted to send back into the network.
The two figures do not have to be the same.
MIC tells you how much the property can take from the network. MEC tells you how much it can send back.
Import and Export Limits Are Not Necessarily Equal
Imagine a home that can comfortably import around 20 kW from the grid.
That does not mean it automatically has permission to export 20 kW.
The local network may only be able to accept 5 kW from that particular connection.
The ability to draw power from the grid does not automatically give the same ability to send power back.
What Does the Main Fuse Tell You?
Many UK homes have a main service fuse rated at something like 60 A, 80 A or 100 A.
That gives an indication of the scale of the electrical supply.
But the main fuse does not tell you everything about available import capacity, export permission, local network capacity or phase arrangement.
The main fuse tells you something about the connection, but it does not define every import or export permission.
Converting Amps to kW
| Current | Approximate Power |
|---|---|
| 16 A | 3.68 kW |
| 32 A | 7.36 kW |
| 60 A | 13.8 kW |
| 80 A | 18.4 kW |
| 100 A | 23 kW |
On a typical single-phase UK supply, a simple approximation is Power ≈ Voltage × Current.
These figures are useful for understanding the scale of a connection.
But they should not be treated as automatic export permissions.
What Is G98?
G98 is the simpler connection route used for qualifying small-scale generation.
The familiar threshold is 16 A per phase, which is approximately 3.68 kW per phase on a typical 230 V supply.
This is why 3.68 kW appears so often in UK solar discussions.
G98 is the simpler route for qualifying small generation that stays within the standard 16 A per-phase threshold.
What Is G99?
G99 applies to larger or more complex generating installations where the DNO needs to assess the proposed connection.
That can include:
- larger solar systems
- battery storage
- multiple inverters
- combined solar and battery systems
- vehicle-to-grid equipment
G99 does not mean the system is unacceptable. It means the connection needs the appropriate DNO assessment.
G99 is the connection-assessment route used when the DNO needs to understand the proposed generating system before it is connected.
What Is G100?
G100 relates to controlling import or export where an agreed limit needs to be enforced.
This can allow a property to have more electrical capability behind the meter than is permitted to cross the grid connection at once.
For example, installed generation capability of 10 kW with an agreed export limit of 5 kW. A compliant control system can limit net export to 5 kW.
G100 separates what can be installed behind the meter from what is allowed to cross the grid connection.
G100 Does Not Replace G98 or G99
- G98
- Small-generation connection route.
- G99
- Generation connection assessment.
- G100
- Import/export limitation and control.
These standards do different jobs.
So a larger system may still require G99 while also using G100 to enforce an agreed export limit.
G98 and G99 deal with connecting generation. G100 deals with controlling the boundary when a limit is imposed.
G100 Is Not Just an Inverter Setting
A compliant export limit is more than selecting a number in an app.
The control scheme needs to:
- measure power flow
- respond to changing conditions
- control the relevant equipment
- operate safely if something fails
A compliant import or export limit is a network-protection function, not just an app setting.
Is 3.68 kW the Maximum UK Solar Export?
No.
This is one of the most common misunderstandings.
3.68 kW is associated with the familiar 16 A per-phase G98 threshold.
It is not a universal UK maximum for solar array size, inverter size or export.
A property can potentially have a larger system through the appropriate DNO connection route.
3.68 kW is not a universal UK export limit. It is the familiar single-phase G98 threshold.
Can You Have More Than 3.68 kW of Solar?
Yes.
A property can potentially have 5 kW, 8 kW, 10 kW or larger systems depending on:
- inverter configuration
- DNO assessment
- export requirements
- network conditions
- phase arrangement
The fact that a solar array exceeds 3.68 kW does not automatically make it unsuitable.
Can You Export More Than 3.68 kW?
Yes, if the DNO approves the connection.
The permitted export could be below 3.68 kW, around 3.68 kW, 5 kW, 10 kW or another site-specific value depending on the network and connection.
The permitted export is determined by the connection arrangement, not by one universal national cap.
More Than 3.68 kW Does Not Automatically Mean Three Phase
A larger solar or battery installation does not automatically require a three-phase supply.
A single-phase home may be able to have a larger G99-approved system.
Three phase may become useful depending on total power, phase loading, network capacity, inverter design and future electrical demand.
More than 3.68 kW of solar does not automatically mean the home needs a three-phase supply.
Installed Generation Capacity vs Agreed Export Capacity
- Installed Generation Capacity
- What the generating equipment is capable of producing.
- Agreed Export Capacity
- What the property is allowed to send into the network.
For example, installed system capability of 10 kW with agreed export of 5 kW.
The system may still be able to generate more than 5 kW if the excess is being used inside the property.
Installed generation capacity describes the equipment. Agreed export capacity describes the network boundary.
Export Limit Does Not Mean Solar Generation Limit
Imagine solar generation of 8 kW, home demand of 2 kW, battery charging of 1 kW and grid export of 5 kW.
The solar system is still generating 8 kW. Only 5 kW is crossing into the grid.
A 5 kW export limit does not necessarily mean the property can only generate 5 kW.
Export Limitation Does Not Make Installed Capacity Unlimited
It is equally important not to take the opposite view.
A G100 export limit does not mean a property can install unlimited generation behind the meter.
The DNO may still need to consider voltage, cable loading, protection, fault contribution, power quality and local network conditions.
Export limitation can unlock larger systems, but it does not make installed generation capacity unlimited.
The DNO Looks at the Complete Installation
Modern homes can have several devices capable of generating or exporting power.
For example a solar inverter, a battery inverter and a vehicle-to-grid charger.
The network assessment can therefore consider the complete installation rather than treating each device as though the others do not exist.
The network looks at the complete generating installation, not each inverter in isolation.
Solar and Battery Power Can Add Up
Imagine a solar inverter of 3.68 kW and a battery inverter of 3.68 kW.
Each device individually looks small. But the overall generating capability of the property can be larger.
The exact assessment depends on the system architecture and controls.
Two individually small inverters can become one larger network connection when they are considered together.
Why Can a Battery Count as Generation?
A battery can charge from the grid, charge from solar, discharge into the home and potentially discharge towards the grid.
Because it can export through its inverter, battery storage can be treated as generating equipment for network-connection purposes.
A battery may charge from the grid, but because it can discharge back towards the grid it can also count as generating equipment.
AC-Coupled vs DC-Coupled Battery Architecture Matters
Not every battery system connects in the same way.
An AC-coupled battery typically has its own inverter connected to the AC electrical system.
A DC-coupled battery may share a hybrid inverter with the solar array.
That can change total inverter capability, application details and export control architecture.
Battery coupling can change what generating equipment the DNO sees at the connection.
How Dynamic Export Limiting Works
A simplified export-control system can be pictured as:
Solar + Battery + Home Load → Grid Metering → Export Controller → Inverter Control
The system continuously measures net flow at the grid connection.
If export approaches the agreed limit, the controller can reduce or redirect power so that the boundary is not exceeded.
This allows the equipment behind the meter to behave dynamically while the grid connection remains controlled.
Worked Example: Larger Solar Behind a Lower Export Limit
Example
Solar generation 10 kW, home demand 2 kW, battery charging 3 kW, export limit 5 kW.
Energy flow: home 2 kW, battery 3 kW, grid 5 kW. Total 10 kW.
The solar array can generate the full 10 kW because all of the electricity has somewhere to go.
Battery storage can absorb power that the network will not allow the property to export.
What Happens When the Battery Fills?
Use the same example. Solar potential 10 kW, home demand 2 kW, export limit 5 kW, battery full.
Now only 2 kW home + 5 kW export = 7 kW has somewhere to go.
The remaining 3 kW of available solar may need to be curtailed.
An export-limited system can generate strongly until the home and battery stop absorbing the difference.
Zero Export Does Not Mean Zero Network Interaction
A system can be configured so that it aims to export 0 kW while still powering the home, charging batteries and generating solar.
But that does not mean the network can ignore the connected generating equipment.
The DNO may still need to consider protection, voltage, equipment capability and failure behaviour.
Zero export does not mean zero network impact.
Why Can Two Identical Homes Get Different DNO Decisions?
Imagine two neighbouring towns with two identical properties.
Both propose the same solar array, the same battery and the same inverter.
The DNO outcomes could still differ.
Because the local network may have different transformer loading, existing generation, cable capacity, voltage conditions and phase balance.
The same equipment can receive different connection conditions in different parts of the network.
Voltage Can Be the Real Export Constraint
Export limits are not only about whether a cable can carry enough current.
When many homes export solar electricity into a local network, voltage can rise.
The DNO needs to keep the network voltage within acceptable limits.
So a location can sometimes run into an export constraint because of voltage before it runs into a simple cable-current limit.
A network can run out of export capacity because of voltage before it runs out of cable current.
DNO Limits Are About More Than Cable Size
A network assessment can consider:
- voltage
- thermal loading
- protection
- fault levels
- phase balance
- power quality
This is why the answer cannot always be predicted from main fuse size, cable size or inverter rating alone.
Import Capacity Matters Too
The discussion around DNO limits often focuses on solar export.
But modern homes are becoming much larger electricity users.
A property may contain a heat pump, EV charger, battery charging, electric cooking, hot-water immersion and a second EV.
Those loads can overlap.
The shift to electric heating, transport and storage makes import capacity just as important as export capacity.
Heat Pump Output Is Not the Same as Electrical Demand
A common misunderstanding is to see 12 kW heat pump and assume it draws 12 kW of electricity.
That is not normally what the figure means.
The 12 kW headline figure usually describes heating output.
The relevant electrical demand can include compressor input, circulation pumps, controls, backup heater and immersion heater.
For the DNO, a heat pump’s electrical demand matters — not its headline heating output.
EV Chargers Can Be Large Domestic Loads
A typical single-phase home EV charger may operate at around 7 kW.
That can be significant when combined with a heat pump, oven, shower, battery charging and other household loads.
But the EV charger does not necessarily have to operate at maximum power all the time.
That is where load management becomes important.
Battery Charging Can Be a Significant Import Load
Example
EV charger 7 kW, battery charging 5 kW, heat pump 3 kW, other household loads 3 kW.
Potential total import: 18 kW.
That may be acceptable on some connections. On others it may need managing.
A home battery is often discussed as though it only helps reduce grid demand.
But while charging from the grid it can become a substantial load.
A battery can be export-limited and still be a significant import load while charging.
Installed Load vs Maximum Demand
A home might contain electrical equipment with a combined rating much greater than its grid connection.
That does not automatically mean the supply is too small.
The key question is: how much of that equipment is allowed to run at maximum power at the same time?
A property can therefore have a 7 kW EV charger, a 5 kW battery charger, a heat pump and other large loads while still remaining within its import limit if those loads are intelligently managed.
Installed electrical load can be greater than the grid connection if the system keeps maximum demand within the limit.
What Is Dynamic Load Balancing?
Dynamic load balancing monitors the electrical demand of the property.
If total import begins approaching the supply limit, a controllable load can reduce its power.
An EV charger might, for example, reduce from 32 A to 20 A or lower while other loads are operating.
When household demand drops, EV charging can increase again.
Load management allows large devices to share a limited grid connection instead of all demanding maximum power at once.
Import Limits Are Often a Control Problem First
Before assuming a home needs a larger fuse, three-phase supply or network reinforcement, it can be worth asking whether the existing electrical capacity can be managed better.
Flexible loads can include EV charging, battery charging and hot-water heating.
These can often wait or reduce power more easily than essential loads.
Before increasing the grid connection, ask whether the existing connection can be used more intelligently.
Priority Control
A whole-home energy system can assign different priorities to different loads.
For example:
- essential home demand
- heat pump
- cooking
- battery charging
- EV charging
The exact order depends on the home.
The important principle is that not every load needs to receive its maximum available power simultaneously.
The question is not how much all the equipment could use at once. It is how much you allow it to use at once.
What Changes with Three Phase?
A three-phase electricity supply distributes electrical power across three phases.
This can provide greater total connection capacity, better load distribution, larger three-phase equipment options and more flexibility for larger solar and battery systems.
But it does not automatically mean three phase is required for every large home-energy system.
The G98 Threshold Is Per Phase
The familiar 16 A G98 threshold is per phase.
On a single-phase connection this equates to roughly 3.68 kW.
On a balanced three-phase connection, 16 A × 3 phases is approximately 11 kW total, depending on the voltage assumptions and system configuration.
Three Phase Is Not Automatically the First Answer
A larger system may be possible on single phase through G99 approval, export limitation or load management.
Three phase can still be valuable, particularly for larger whole-home systems.
But it should solve a genuine design problem.
Three phase can increase design flexibility, but it is not automatically the first solution to a larger solar or battery system.
Fuse Upgrade vs Three-Phase Upgrade
- Fuse Upgrade
- Increases the allowable current on the existing supply, where the network and service equipment can support it.
- Three-Phase Upgrade
- Changes the electrical supply architecture.
They solve different problems.
Increasing the main fuse and upgrading to three phase solve different problems.
A Bigger Fuse Does Not Mean Bigger Export Permission
A property may have a 100 A main fuse.
That does not automatically mean it can export 23 kW.
The fuse primarily relates to the incoming supply. Export permission still depends on the DNO and local network.
A bigger import fuse does not automatically mean a bigger export allowance.
Adding Battery kWh vs Adding Inverter kW
This distinction is very important when expanding a battery system.
Upgrade A — original battery 10 kWh, expanded battery 20 kWh, inverter remains 5 kW. The stored energy has increased. The network power capability may be largely unchanged.
Upgrade B — original system 5 kW inverter, add another 5 kW inverter system. Now the network power capability may change significantly.
Adding storage capacity and adding power electronics are very different DNO changes.
Future Expansion Can Trigger a New DNO Check
An existing system may have been approved with a particular inverter, particular generation capacity and a particular export limit.
If the homeowner later adds another inverter, larger solar, another battery system or vehicle-to-grid equipment, the original arrangement may need reviewing.
DNO approval applies to the connection configuration that was assessed, not every future upgrade you may add to it.
Grid Limits vs Backup Limits
When the property is connected normally to the grid, DNO import and export limits matter at the network boundary.
During a properly configured backup event, the home is disconnected from the grid and different limits become important.
These include battery power, inverter power, gateway rating and protected-load design.
Grid limits tell you what can cross the boundary. Backup limits tell you what can operate when that boundary is disconnected.
Backup Must Not Energise a Dead Grid
Important
When a property operates in islanded backup mode during a power cut, the system must be appropriately separated from the public electricity network.
That prevents the home's generation or battery from energising a network that should be de-energised.
This is a fundamental safety requirement of backup design.
What Happens When the DNO Offers Less Than Requested?
A DNO application is not always simply approved or rejected.
Possible outcomes can include:
- full requested export approved
- lower export capacity offered
- G100 export limitation required
- different connection conditions
- phase changes suggested
- network reinforcement required
A DNO application is often a design conversation, not just a yes-or-no decision.
A Lower Export Offer Does Not Automatically Kill the Project
Imagine the design requests 10 kW export but the DNO offers 5 kW.
That does not automatically mean the project needs to be abandoned.
Possible design responses can include:
- accepting 5 kW export
- using G100 export limitation
- adding or better using battery storage
- accepting some curtailment
- changing inverter configuration
- considering three phase
- investigating network reinforcement
A lower export offer does not automatically kill the project; it changes the design problem.
G99 Does Not Automatically Mean Network Reinforcement
A homeowner may hear G99 and assume expensive network work is inevitable.
That is not necessarily the case.
The DNO may decide that the requested system can connect as proposed, that an export limit is needed, that a different arrangement is required, or that reinforcement is necessary.
A G99 application asks the DNO what the network can support; it does not automatically mean the network must be upgraded.
DNO Permission and Export Tariffs Are Separate
The DNO and electricity supplier do different jobs.
The DNO determines what the network connection can accept.
The electricity supplier determines what it will pay for exported electricity.
A supplier might offer an attractive export tariff. That does not give permission to exceed the DNO export limit.
The DNO decides what the network can accept. The supplier decides what it will pay you for exporting.
A Tariff Cannot Override the DNO Limit
Suppose an export tariff rewards high export during a particular time window.
The home may want to export from solar, battery or V2G.
But the combined net export must still remain within the agreed network limit.
A tariff can reward export, but it cannot override the network connection limit.
Worked Example: One Grid Connection, Many Technologies
Example
A single-phase home with solar capability 8 kW, battery inverter 5 kW, EV charger 7 kW, heat pump electrical input 3 kW, variable other household load, agreed export limit 5 kW.
Sunny afternoon — solar generation 8 kW, home demand 1 kW, battery charging 2 kW, export 5 kW. Total 1 + 2 + 5 = 8 kW. All available solar has somewhere to go.
Cheap overnight period — EV charging 7 kW, battery charging 5 kW, heat pump 2 kW, other home demand 2 kW. Potential total import 16 kW.
Instead of allowing all of those loads to operate at maximum power, a HEMS or load-management system could reduce EV charging and battery charging while protecting more important loads.
A modern home can contain more electrical capability than the grid connection allows at once, provided the loads are intelligently coordinated.
What Should a Good Whole-Home Energy Proposal Show?
A good proposal should explain the grid connection, not simply list individual products.
It should ideally identify:
- current supply type
- main fuse rating
- single or three phase
- existing generation
- proposed solar inverter capacity
- battery inverter capacity
- combined generation capability
- expected maximum import demand
- proposed export
- expected G98 or G99 route
- whether G100 is expected
- load-management strategy
- what happens if the DNO offers less than requested
“Subject to DNO” should not be the end of the explanation. The proposal should show what is being requested and what happens if the network offers less.
What DNO Paperwork Should You Keep?
The connection paperwork forms part of the technical record of the property.
Depending on the installation, useful documents can include:
- G98 notification
- G99 application and approval
- agreed export capacity
- G100 export-limitation details
- commissioning records
- inverter details
- equipment references
- single-line diagram
These can become useful if the system is later expanded, repaired, sold or redesigned.
Your DNO connection paperwork is part of the technical record of the property.
Common DNO Import and Export Questions
What is a DNO?
The Distribution Network Operator manages the local electricity network supplying your property.
Is the DNO my electricity supplier?
No. Your supplier sells and bills you for energy. The DNO manages the physical electricity distribution network.
What is an import limit?
It is the amount of electrical power the property can take from the network under its connection arrangement.
What is an export limit?
It is the maximum net power the property is allowed or configured to send back into the grid.
What are MIC and MEC?
MIC means Maximum Import Capacity. MEC means Maximum Export Capacity.
Is 3.68 kW the maximum UK solar export?
No. It is the familiar single-phase G98 threshold, not a universal UK export cap.
Can I have more than 3.68 kW of solar?
Yes, potentially, subject to the appropriate connection route and network conditions.
Can I export more than 3.68 kW?
Yes, if the DNO agrees a higher export capacity.
What is G98?
G98 is the simpler connection route for qualifying small-scale generation up to the relevant per-phase threshold.
What is G99?
G99 is the connection-assessment route used for larger or more complex generating installations.
What is G100?
G100 relates to compliant schemes used to control import or export at the grid connection.
Does G100 replace G99?
No. G100 can be used alongside the relevant G98 or G99 connection arrangement.
Does battery storage count towards G99?
It can, because battery storage can export through its inverter and is therefore relevant to the generation connection assessment.
Do solar and battery inverter ratings add together?
They can contribute to aggregate generation capability, but the exact assessment depends on the system architecture and controls.
Can I install a larger solar array with a lower export limit?
Potentially. Electricity can be used by the home or battery while net export remains within the agreed limit.
What is zero export?
A zero-export system aims to prevent net generation from being sent into the grid.
Does zero export mean I do not need DNO involvement?
Not necessarily. Connected generating equipment can still affect the network and may still require the appropriate notification or assessment.
Can a battery help with export limits?
Yes. It can absorb surplus generation while it has spare capacity and sufficient charge power.
What happens when the battery fills?
If household demand is low and the export limit has been reached, solar generation may need to be curtailed.
Does a 100 A fuse mean I can export more?
No. A larger main fuse does not automatically create a larger export allowance.
Can a heat pump overload my electricity supply?
A heat pump adds electrical demand, but whether it causes an import issue depends on its electrical input, auxiliary heaters and other loads operating at the same time.
Does a 12 kW heat pump draw 12 kW of electricity?
Not normally. The 12 kW figure generally describes heating output rather than electrical input.
Can an EV charger dynamically reduce its power?
Yes. Dynamic load balancing can reduce EV charging power when household demand increases.
Can battery charging be load-managed?
Yes. Battery charge power can be controlled to keep total import within an agreed limit.
Do I need three phase for more than 3.68 kW of solar?
Not automatically. Larger systems may be possible on single phase through the appropriate DNO connection route.
What is the difference between a fuse upgrade and three phase?
A fuse upgrade increases current capacity on the existing supply where possible. Three phase changes the electrical supply architecture.
Does G99 mean network reinforcement?
No. The DNO may approve the request, offer a lower export limit, require export limitation or identify reinforcement.
Why might my neighbour get a different export allowance?
Different properties can sit on different parts of the network with different voltage, transformer, cable and generation conditions.
Can I add another battery without contacting the DNO?
Adding only storage capacity behind the same power electronics may be different from adding another inverter. Any change to generating capability should be checked against the existing connection approval.
Does adding battery kWh matter as much as adding inverter kW?
Usually not from a network-power perspective. Increasing inverter power can materially change the site’s import or export capability, whereas increasing kWh behind the same inverter may not.
Can an export tariff override the DNO export limit?
No. The tariff determines financial value. The DNO connection determines the network limit.
What happens if the DNO approves less export than I requested?
The design can potentially be changed using export limitation, battery storage, altered equipment, curtailment, three phase or network reinforcement.
Manage the Grid Connection, Not Just the Individual Products
A modern home can contain solar, battery storage, EV charging, heat pumps and backup power.
But all of them still interact with one electricity connection.
The goal is not simply to ask whether each individual product will fit.
It is to understand:
- how much the home can import
- how much it can export
- which equipment contributes to each direction
- how demand can be prioritised
- how export can be controlled
- where the grid boundary sits
Your electricity supplier sells you energy. Your DNO manages the network that carries it.
The grid connection is the boundary. Everything behind it has to share the available import and export capacity.
3.68 kW is not a universal UK export limit. It is the familiar single-phase G98 threshold.
The network looks at the complete generating installation, not each inverter in isolation.
The question is not how much all the equipment could use at once. It is how much you allow it to use at once.
A lower export offer does not automatically kill the project; it changes the design problem.
A modern home does not need unlimited grid capacity. It needs its available import and export capacity to be managed intelligently.