Home Heat Pump Guide

Heat Pump and EV Charger: Can Your Home Handle Both?

As more UK households switch from gas boilers to heat pumps and from petrol cars to electric vehicles, a practical question arises: can your home's electrical supply handle both? The short answer for most homes is yes — but it requires some thought about electrical capacity, load management, and smart scheduling to do it safely and cost-effectively.

This guide walks you through the electrical considerations, the costs involved, and how to make both systems work harmoniously on a typical UK domestic supply.

The Electrical Demand: Heat Pump + EV Charger

Let us start with the numbers. Here is what each system typically draws:

Heat Pump

  • Electrical input: 1.5 to 5 kW (this is the electricity drawn, not the heat output)
  • Typical draw during normal operation: 2 to 3.5 kW for a standard 8 to 12 kW unit
  • Peak draw (startup or high demand): Up to 5 to 7 kW briefly, though modern inverter-driven units ramp up gradually

EV Charger

  • Standard home charger (7 kW): Draws approximately 30 amps at 230 volts = 7 kW
  • Reduced-rate charging (3.6 kW): Some chargers can be set to charge at half speed, drawing ~16 amps = 3.6 kW
  • Three-phase charger (22 kW): Only for homes with three-phase supply — rare in UK residential settings

Combined Demand

If both are running simultaneously at full power:

  • Heat pump: 3.5 kW + EV charger: 7 kW = 10.5 kW
  • Add other household loads (lights, oven, kettle, shower): 3 to 10 kW
  • Worst-case total: approximately 15 to 20 kW

A standard single-phase supply with a 100-amp fuse provides approximately 23 kW capacity. So even in the worst case, you are within limits — though without much headroom for an electric shower (10 kW) running at the same time.

With an 80-amp fuse (approximately 18 kW capacity), things get tighter, and with a 60-amp fuse (approximately 14 kW), you may need either a fuse upgrade or load management.

Why It Usually Works Fine

The theoretical worst case rarely happens in practice. Here is why:

Diversity of Loads

Not everything runs at maximum power at the same time. The heat pump modulates its output (an inverter-driven compressor adjusts speed rather than running at full blast). The kettle runs for three minutes. The oven cycles on and off. The EV charger typically runs overnight when other loads are minimal.

Smart EV Chargers Adapt

Modern smart EV chargers — which are now mandatory for new installations under UK building regulations — can dynamically adjust their charging rate based on available supply. If your heat pump is drawing 4 kW and your house needs another 3 kW, the charger automatically reduces from 7 kW to 6 kW (or whatever is needed) to stay within your supply limit.

Chargers with this capability include:

  • myenergi zappi: Full load management with CT clamp monitoring of your supply. Excellent integration with solar panels too.
  • Ohme: Smart scheduling and dynamic load adjustment.
  • Hypervolt: Built-in load balancing and solar integration.
  • Pod Point Solo 3: Smart features with demand management.

EV Charging Is Usually Overnight

Most EV owners charge overnight when electricity is cheapest and household demand is lowest. Between midnight and 6am, your heat pump is running at low output (maintaining temperature rather than heating from cold), the oven and shower are off, and the EV charger can use most of the available capacity without competition.

When You Might Need an Upgrade

There are situations where your electrical supply may not be sufficient without some action:

60-Amp Main Fuse

Older properties with a 60-amp fuse have only ~14 kW of capacity. A heat pump (3.5 kW) plus EV charger (7 kW) alone is 10.5 kW, leaving just 3.5 kW for everything else. Running an electric shower at the same time would exceed the limit.

Solution: Upgrade to a 100-amp fuse. This is done by your Distribution Network Operator (DNO) and is usually free if the existing cable from the street can handle it. Apply through your installer or electrician.

Older Wiring or Small Consumer Unit

Some older homes have outdated wiring or a consumer unit that cannot accommodate the additional circuits needed for a heat pump and EV charger. Each needs a dedicated MCB (circuit breaker) and properly sized cabling.

Solution: A consumer unit upgrade costs £500 to £1,000. This is often recommended during a heat pump installation anyway, as modern safety standards require RCD protection.

No Load Management

If you have a basic "dumb" EV charger without load management, it will draw 7 kW regardless of what else is running. Combined with a heat pump peak and an electric shower, you could exceed your supply.

Solution: Either replace the charger with a smart model (£800 to £1,200 installed) or add a CT clamp-based load management device. Since January 2023, all new home EV charger installations in England must be smart chargers, so this mainly affects older installations.

The Best Setup: Heat Pump, EV Charger, and Smart Tariff

The most cost-effective approach combines all three elements:

Step 1: Smart Tariff

A time-of-use tariff like Octopus Go or Intelligent Octopus gives you very cheap overnight electricity (7p to 9p per kWh) for both EV charging and heat pump operation. This is where the biggest savings come from — potentially £500 to £1,000 per year less than flat-rate pricing for both systems combined.

Step 2: Smart Scheduling

Programme both systems to do their heaviest work during the cheap overnight window:

  • EV charger: Set to charge between midnight and 5am (most EVs need 3 to 5 hours for a typical daily top-up)
  • Heat pump: Pre-heat the house and hot water cylinder during the cheap window, then maintain temperature during the day at a lower output

Step 3: Load Management

A smart EV charger with CT clamp monitoring ensures the two systems share the available electrical capacity safely. The charger automatically backs off if the heat pump needs more power, and vice versa.

Step 4: Solar (Optional)

If you add solar panels, you can charge your EV for free during the day (if it is parked at home) and offset daytime heat pump electricity. A myenergi zappi charger specifically prioritises solar electricity for EV charging when available.

Real-World Example: The Electrified Home

Let us model a typical scenario for a 3-bed semi-detached house in 2026:

Before Electrification

  • Gas boiler: £800/year (gas at 6p/kWh)
  • Petrol car (10,000 miles/year): £1,400/year (at 145p/litre)
  • Household electricity: £720/year (3,000 kWh at 24p)
  • Total: £2,920/year

After Electrification (Heat Pump + EV + Smart Tariff)

  • Heat pump electricity: £600/year (4,000 kWh, optimised with smart tariff averaging ~15p/kWh)
  • EV charging: £300/year (2,500 kWh at average ~12p/kWh on Octopus Go overnight rate)
  • Household electricity: £720/year (unchanged)
  • No gas standing charge: -£100/year saved
  • Total: £1,520/year

Annual saving: approximately £1,400

This is a realistic scenario based on current tariffs and typical consumption. The combination of a heat pump and EV, both powered by cheap overnight electricity, creates a powerful financial case for electrifying your home.

Practical Considerations

DNO Notification

Both a heat pump and an EV charger require notification to your Distribution Network Operator. Your installers handle this, but be aware that it needs to be done for both systems. If both are being installed around the same time, coordinate to ensure the notifications reflect the combined load.

Consumer Unit Space

Each system needs a dedicated circuit in your consumer unit — typically a 20-amp MCB for the heat pump and a 32-amp MCB for the EV charger. If your consumer unit is full, you may need an extension or replacement.

Cable Runs

The EV charger needs a dedicated cable from the consumer unit to the charging point (usually on the front of the house or in a garage). The heat pump needs a dedicated cable to the outdoor unit (usually at the side or rear). Plan the cable routes during the survey to minimise cost and disruption.

Future-Proofing

If you are only installing one system now but plan to add the other later, tell your electrician. They can size the cabling and consumer unit with the future load in mind, avoiding the need for another visit.

Frequently Asked Questions

Can I install a heat pump and EV charger at the same time?

Yes, and it can be more cost-effective to do so — you save on electrician call-out charges and can plan the consumer unit layout for both systems at once. However, the two installations are usually done by different specialists (heat pump installer and EV charger installer), so coordination is needed.

Will a heat pump and EV charger trip my electricity?

Not if properly installed with load management. A smart EV charger with a CT clamp automatically reduces charging speed if the total household demand approaches your supply limit. Your installer should calculate maximum demand and install appropriate protection.

Do I need three-phase electricity for a heat pump and EV charger?

In most cases, no. A single-phase 100-amp supply comfortably handles a standard heat pump plus a 7 kW EV charger with smart load management. Three phase is only necessary for very large properties with high overall demand. See our single phase vs three phase guide for details.

Which should I install first — the heat pump or the EV charger?

Install whichever you need more urgently. If your boiler is failing, prioritise the heat pump. If you have just bought an EV, get the charger first. There is no technical reason why one must come before the other, though installing the heat pump first gives you time to establish your electricity usage pattern before adding the EV charger's demand.

Can solar panels power both a heat pump and an EV charger?

Partially, yes. A 4 kWp solar system can offset some of both systems' electricity consumption, particularly in summer. A smart system like myenergi's ecosystem (eddi solar diverter, zappi EV charger) can intelligently distribute solar electricity between your heat pump hot water, EV charging, and household needs.

What about battery storage with a heat pump and EV?

A home battery adds another layer of flexibility — storing cheap overnight or solar electricity for peak hours. However, with a heat pump and EV already providing significant load-shifting opportunities, the marginal benefit of a battery is smaller than for a household with just solar panels. Run the numbers for your specific situation before investing.

The Bottom Line

Most UK homes can comfortably handle both a heat pump and an EV charger on a single-phase electricity supply, provided you have a 100-amp fuse and a smart EV charger with load management. For homes with a 60-amp or 80-amp fuse, a free or low-cost upgrade from your DNO usually resolves the issue.

The combination of a heat pump and an EV, both powered by a smart time-of-use tariff, is one of the most effective ways to reduce household energy costs in the UK. Annual savings of £1,000 to £1,500 compared to gas heating and petrol driving are realistic — and the environmental benefits of eliminating fossil fuels from both your home and your car are substantial.

Talk to your heat pump installer and electrician about your full electrification plans from the outset. Planning both systems together ensures your electrical supply, consumer unit, and wiring are ready for everything you need — now and in the future.