Import capacity
This is how much electricity the property connection can take from the network.
Upgrading to three phase can substantially increase the total power potentially available to the property.
Home electricity connections explained
Should I upgrade my home to three-phase electricity for solar?
Three phase can give a home substantially more electrical capacity, make larger solar and battery systems easier to accommodate and open the door to more powerful EV charging.
But there is a catch: upgrading the supply can be expensive, and having three phases does not automatically mean the electricity network will let you export as much solar as you want.
The short answer
Three phase can be excellent for a heavily electrified home — but do not upgrade blindly.
Most British homes have historically been supplied with single-phase electricity.
For an ordinary household with conventional appliances, that has generally been more than adequate.
But homes are changing.
Solar inverters are becoming larger.
Home batteries can charge and discharge at several kilowatts.
7kW EV chargers are increasingly common.
Some households want two EV chargers.
Heat pumps are moving heating demand onto electricity.
Electric hot water adds another large load.
For some properties, three phase provides useful capacity and room for future growth.
But ask the DNO question before spending the money.
If your main reason for upgrading is to obtain more solar export capacity, establish what the local Distribution Network Operator is likely to permit first. Three phase does not automatically guarantee a larger export allowance.
Start with the basics
What does single phase actually mean?
A normal single-phase household connection has one live electrical phase feeding the property.
That one phase supplies the consumer unit, sockets, lighting and other household electrical equipment.
For decades that was entirely sensible.
A house might have had a cooker, kettle, washing machine, television and lighting, with gas dealing with space heating and often hot water.
Today that same service may be asked to support:
a 7kW EV charger;
an electric heat pump;
an immersion heater;
a substantial battery inverter;
and solar generation exporting in the opposite direction.
What changes?
Three phase gives the property three electrical phases instead of one.
1
Live phase on a normal single-phase domestic connection.
3
Live phases available on a three-phase connection.
≈69kVA
Maximum connection capacity commonly offered for domestic and
small-business three-phase upgrades, subject to the network.
This allows electrical loads and generation to be distributed across three phases rather than concentrating everything on one.
Three phase has been normal in commercial and industrial buildings for many years because those properties often require considerably more power.
As homes electrify, it is becoming increasingly relevant domestically too.
Solar makes this interesting
Three phase changes the G98 calculation dramatically.
G98 applies to qualifying fully type-tested microgeneration up to 16 amps per phase.
On a single-phase supply, 16 amps at nominal UK voltage corresponds to approximately:
3.68kW
On a qualifying three-phase installation the equivalent aggregate figure is approximately:
11.04kW
That is three times the single-phase figure because the generation is spread across three phases.
Important qualification
11.04kW does not mean every three-phase home automatically gets an 11kW solar system.
The 16A-per-phase threshold tells you whether qualifying generation can fall within the G98 framework.
It does not override:
inverter type-test requirements;
the property's actual electrical connection;
phase-balance requirements;
local network conditions;
existing generation or storage;
or any other applicable DNO connection rules.
Three phase makes larger generation easier to distribute.
It does not remove the need for proper system design or network compliance.
Import versus export
This is the distinction that causes most confusion.
Export capacity
This is how much generation the DNO agrees the property may send back onto the network.
Export capacity depends on local network conditions as well as the property's own connection.
A bigger electrical supply does not automatically create spare export
capacity in the street.
The crucial solar question
Will upgrading to three phase get me a larger G99 permission?
It may help — but it cannot be promised.
Imagine a homeowner currently has single phase and wants a large solar-and-battery system.
Moving the property to three phase may remove one constraint because the generation can now be distributed across three phases.
But the DNO still has to assess:
local voltage;
LV feeder capacity;
transformer capacity;
existing solar and generation nearby;
battery inverter behaviour;
and the requested maximum export.
Do not spend thousands upgrading purely on an assumption.
If the objective is a particular solar export capacity, seek the DNO's position before committing to the supply upgrade wherever practicable.
A useful example
Why three phase becomes attractive on a heavily electrified home.
Large solar array
A property may want 8–12kWp or more of solar generation rather than designing everything around a 3.68kW single-phase inverter.
Substantial battery storage
Larger hybrid or battery inverters may be capable of several kilowatts of charging and discharging.
Multiple EVs
Two electric vehicles can create substantial overnight or daytime charging demand.
Heat pump
Heating adds another significant electrical load, especially during cold weather.
None of these automatically requires three phase individually.
It is the combination that can make the upgrade increasingly sensible.
Electric vehicles
Could three phase give me faster EV charging?
Potentially.
The familiar domestic EV charger is around 7kW and normally operates from a single phase.
Three-phase installations can also support higher-power charging arrangements such as approximately 11kW or 22kW where:
the vehicle can accept that AC charging rate;
the charger supports three phase;
the DNO connection capacity is sufficient;
the household installation is designed for it;
and load management is considered where necessary.
There is little benefit in paying for a 22kW charger if the vehicle itself can only accept 7kW or 11kW AC.
Heat pumps
Does a heat pump mean I need three phase?
Usually not by itself.
Many domestic heat pumps are designed to work perfectly well from a conventional single-phase household supply.
Three phase becomes more relevant where:
the heat pump itself is unusually large;
the house is large or highly electrically heated;
there are multiple EV chargers;
substantial battery charging is planned;
or several high-power loads may operate together.
Diversity still matters.
A house containing 30kW worth of appliances does not necessarily draw 30kW continuously. Proper maximum-demand calculations and load management can sometimes avoid an unnecessary connection upgrade.
The expensive bit
Why can a three-phase upgrade cost so much?
The answer depends on one very simple question:
“Where is the nearest suitable three-phase network?”
If suitable three-phase infrastructure already exists immediately outside the property, the job may involve a relatively short new service connection and alterations around the meter position.
But that is the easy case.
A more difficult property might require:
a new service cable;
excavation through a garden or driveway;
pavement excavation;
road crossings and traffic management;
extension of the local LV network;
replacement of overhead lines;
replacement or upgrading of the local transformer;
wayleaves or other land permissions.
A real network example
Sometimes the house is not the expensive part at all.
SSEN's published connection-charging methodology gives an example of a domestic property requesting a three-phase connection where the local infrastructure only provides single phase.
In that example, supplying three phase requires:
replacement of around 100 metres of single-phase overhead LV line;
replacement of the existing single-phase transformer;
and conversion of those assets to three phase.
That illustrates why quotations can vary so dramatically between apparently similar houses.
The expensive question is not “How many phases do I want?”
It is “What network construction work is necessary to deliver those phases to this property?”
There is no useful universal price
Be suspicious of anyone quoting a standard three-phase upgrade cost without seeing the network.
Three-phase domestic upgrades are generally chargeable.
The actual DNO quotation depends on the work required.
An Energy Networks Association innovation project examining domestic three-phase upgrades used a conventional upgrade cost range of around £3,500–£6,000 as a modelling assumption.
That is useful context — but not a price list.
Where substantial reinforcement is needed, individual quotations can be significantly higher.
Get the actual DNO quotation before designing the project around three phase.
A modest upgrade may make perfect economic sense. A network-reinforcement project costing many thousands of pounds can completely change the calculation.
Another complication
The meter and consumer installation may need changing too.
The DNO owns and controls the incoming network service and cut-out.
Your electricity supplier is responsible for the meter.
The homeowner's electrician deals with the customer's own electrical installation.
A three-phase upgrade can therefore involve coordination between several parties.
DNO service cable and cut-out work
three-phase metering arrangements
consumer-unit or distribution-board work
new tails and isolation arrangements
redistribution of circuits across phases
solar, battery and EV equipment changes
The DNO quotation is therefore not necessarily the total cost of converting the property.
Do I already have it?
How do I know whether my house is single phase or three phase?
The meter and cut-out area often gives the answer.
A conventional single-phase connection typically has one live phase and one main DNO fuse.
A three-phase installation normally has three live phases and corresponding service equipment.
Do not dismantle electrical equipment to check.
The DNO or a qualified electrician can confirm the supply safely. Network records and the MPAN can also help establish the existing connection.
When I would seriously consider it
Three phase starts to make sense when several future requirements point in the same direction.
Large solar design
You genuinely need substantially more generation and inverter capability than a small single-phase arrangement provides.
Multiple EVs
The household has, or expects to have, several electric vehicles and significant charging demand.
Heat pump and electric heating
The home is moving a large proportion of its energy demand from fossil fuels onto electricity.
Large battery system
High-power battery charging and discharging forms part of the long-term energy design.
Workshop or other equipment
The property also has motors, machinery or equipment that genuinely benefits from three-phase supply.
Long-term ownership
The household expects to remain in the property and benefit from the additional electrical capability for many years.
When I would hesitate
Do not upgrade merely because three phase sounds “better”.
A conventional single-phase connection is still perfectly adequate for huge numbers of British homes.
I would question the upgrade where:
the proposed solar system is modest;
there is only one normal 7kW EV charger;
the heat pump is comfortably within the existing supply capacity;
load management can solve occasional peak demand;
the DNO quotation involves major reinforcement;
or the homeowner has no realistic use for the extra capacity.
More capacity is useful only if you have something useful to do with it.
Future-proofing
Could three phase make a home more attractive in the future?
Potentially.
A three-phase connection can give a property greater flexibility for future electrification.
A later homeowner may want:
larger solar;
multiple EV chargers;
high-power battery storage;
a larger heat pump;
electric heating;
or workshop equipment.
Having suitable three-phase infrastructure already established can therefore be a practical property advantage.
But we cannot honestly put a guaranteed house-price figure on it.
Three phase should be viewed primarily as increased electrical capability, not marketed as a guaranteed investment return.
Before applying
Work backwards from what the property actually needs.
The sensible sequence is:
1. Calculate realistic existing household demand.
2. Add planned EV, heat-pump and other major loads.
3. Design the appropriate solar and battery system.
4. Establish the required inverter and export capacity.
5. Check what the existing single-phase supply can support.
6. Ask the DNO what generation/export arrangement is available.
7. Obtain the three-phase upgrade quotation if it is genuinely needed.
8. Compare the cost with alternatives such as load or export limitation.
Three phase should be the solution to an identified problem.
It should not be the starting assumption simply because a larger number sounds more future-proof.
Frequently asked questions
Three-phase electricity and solar answered.
What is the difference between single phase and three phase?
Single phase gives a normal domestic property one live phase. Three phase provides three live phases, allowing demand and generation to be spread across them and potentially providing substantially greater total electrical capacity.
Can three phase allow me to have more solar?
Potentially yes. It can make larger generation arrangements easier to accommodate and allows generation to be distributed across three phases. The DNO still controls the connection and permitted export.
Can I have 11.04kW under G98 on three phase?
G98 covers qualifying fully type-tested microgeneration up to 16 amps per phase. At nominal UK voltage that corresponds to approximately 3.68kW single phase or 11.04kW aggregate across a qualifying three-phase installation.
Does three phase guarantee more solar export?
No. Import capacity and export capacity are different. The DNO still assesses local voltage, cables, transformers and existing generation before agreeing the requested export.
How much power can a domestic three-phase supply provide?
DNOs commonly offer domestic and small-business three-phase connections up to around 69kVA, subject to the local network and requested connection capacity.
Is upgrading to three phase expensive?
It can be. Three-phase upgrades are generally chargeable. If the local network already has suitable three-phase infrastructure, the work may be relatively straightforward. If cables, transformers or other network assets require reinforcement, the cost can become substantial.
Can I have faster EV charging on three phase?
Potentially. Three phase can support higher-power EV charging where the vehicle, charger, household installation and DNO connection capacity all permit it.
Do I need three phase for a heat pump?
Most ordinary domestic heat pumps do not require it. Three phase becomes more relevant where total household electrical demand is high or several large electrical technologies are being combined.
Do I need three phase for a 10kW solar inverter?
Not universally. The correct answer depends on the inverter, property connection and DNO requirements. At higher domestic generation levels, a three-phase arrangement may be preferred or required.
How do I know if my house already has three phase?
The meter and cut-out arrangement often shows the number of phases, but the safest approach is to have the supply confirmed by a qualified electrician or the DNO.
Should I upgrade solely to obtain a bigger G99?
Not without checking the network position first. Three phase does not guarantee a particular export allowance, so establish what the DNO is likely to permit before paying for the upgrade.
Is three phase useful for future-proofing?
It can be. Additional connection capacity may be useful for future solar, batteries, EV charging, heat pumps and other electrical equipment, particularly where a household expects continuing electrification.
Official guidance checked
The network position matters more than rules of thumb.
This guide was reviewed against current material available in August 2026 including:
- Energy Networks Association — Engineering Recommendation G98.
- Energy Networks Association — G99 connection guidance.
- Scottish and Southern Electricity Networks — supply capacity and three-phase upgrade guidance.
- Scottish and Southern Electricity Networks — connection charging methodology.
- SP Energy Networks — additional load and three-phase connection guidance.
- UK Government and Ofgem — Electricity Networks Connections Action Plan.
Every property and local network is different. The current DNO connection offer and relevant engineering requirements take precedence over this general homeowner guide.
Related Tom Solar guides
Understand the rest of the electrical system.
Tom Solar view
Find out what the house needs before deciding how many phases it needs.
Three phase can be an excellent upgrade for the right property.
A heavily electrified home with substantial solar, battery storage, EV charging and electric heating may genuinely benefit from the additional capacity and flexibility.
But upgrading purely because a larger electrical connection sounds impressive can be an expensive mistake.
Design the future home first. Then decide whether three phase is necessary to support it.
And if solar export is the reason for the upgrade, check the DNO position before assuming the extra phase capacity will translate into the export allowance you want.