Installing a home battery and an EV charger together, rather than as two unrelated projects, means both can be scheduled to draw from the same off-peak window on a tariff such as Octopus Intelligent - reducing the cost of running the home and the vehicle at the same time. This applies whether or not solar is also part of your plans; the practical starting point is a load assessment of your existing supply and consumption pattern. Dynamic load balancing between the battery, EV charger and household loads keeps combined demand within the main supply fuse rating, even when multiple high-power devices are operating. If solar is also present, surplus daytime generation can be directed to both the home battery and the vehicle. The financial benefit of this arrangement depends on vehicle usage, battery capacity, solar generation and the tariff structure in use. Battery performance depends on system design, tariff structure, usage profile and electrical infrastructure. We model these factors before specifying equipment. EV charging is usually a high-load item, so it should not be assumed to run from backup power without a specific design review of battery capacity and inverter output; see our complete energy ecosystem page for how backup planning fits into a combined system. For an overview of the full battery range, visit our battery storage hub. For EV charger options, see our EV charging systems page. If bidirectional charging is of interest, see Vehicle-to-Home and Vehicle-to-Grid charging.
.png)
Octopus Intelligent manages EV charging and home battery charging as a coordinated overnight programme. The Octopus API schedules both devices to complete charging within the off-peak window, typically from around 23:30 to 05:30. The home battery fills its full capacity. The EV charges to the target state of charge. Both draw from the same lower-cost overnight rate. The financial value this generates depends on vehicle battery size, annual mileage, household consumption, the prevailing off-peak tariff rate, and future energy price changes. For households with a large EV and a home battery, the combined reduction in energy costs can be significant - we model the likely range at survey stage rather than quoting fixed annual figures.
A luxury Surrey or SW London property with a 100A single-phase supply has a maximum safe simultaneous load of approximately 23kW. A 7.4kW EV charger running concurrently with a 5kW battery charging at peak rate, a 7kW induction hob, and a 3kW heat pump compressor cycle brings total simultaneous demand to 22.4kW - within 600W of the supply limit. Without active dynamic load management, an unplanned load spike crosses the supply fuse rating. Our integrated systems install a current transformer on the main incoming tails that feeds real-time total demand data to the battery inverter and the EV charger simultaneously. Both devices modulate their output in response to keep total demand within the supply limit at any instant - completely in the background, with no user intervention required.
Modern large-format EVs carry substantial battery capacity - enough, through Vehicle-to-Home technology, to contribute meaningfully to household energy supply during outages or high-tariff periods. We design every battery and EV charger installation with the earthing topology, consumer unit architecture, and cable sizing that V2G and V2H systems will require when bidirectional chargers become mainstream in the UK. The infrastructure installed today is designed to support this capability without structural rework. The home battery component of a combined installation may qualify for 0% VAT under HMRC energy-saving materials rules - eligibility and the applicable VAT position are confirmed at survey and quotation stage.
We retrieve your half-hourly Smart Meter consumption data, map your full estate load profile, and confirm your incoming supply rating and available simultaneous capacity. This assessment establishes whether dynamic load balancing is required and determines the maximum EV charger output and battery charge rate that can operate concurrently within safe margins.
Battery capacity, EV charger specification, CT sensor placement, and dynamic load balancing configuration are co-designed as a single programme. We select the battery platform and EV charger combination with confirmed Octopus Intelligent API compatibility and V2H-ready earthing topology from the outset.
Our qualified engineers install the battery, EV charger, and CT sensor load balancing hardware as one co-ordinated programme. All cabling is concealed through building fabric. The EV charger is positioned for architectural integration with concealed cable routing to the parking location. Battery installation follows PAS 63100 fire safety standards throughout.
We configure the Octopus Intelligent API link for both the home battery and the EV charger, verify dynamic load balancing is operating correctly across the full simultaneous load range, and issue all warranty documentation and the appropriate VAT invoice before engineers leave. Both systems begin operating in coordinated overnight mode from commissioning day.
Between 23:30 and 05:30, the Octopus Intelligent API co-ordinates both the home battery and the EV charger to draw simultaneously from the grid at 7 to 9p/kWh - filling two storage vessels in one cheap overnight window.
The home battery management system and the EV charger both connect to the Octopus API. The API receives half-hourly grid pricing data 24 hours ahead and schedules the optimal charge session for both devices within the scheduled off-peak window. By 05:30, the Taycan or Model 3 is charged to target state and the home battery holds a full 13.5kWh of electricity purchased at under 9p/kWh - which then powers the estate throughout the day at full grid replacement value of 25 to 35p/kWh.
Simultaneously charging a 7.4kW EV and a 5kW home battery on a property already running heat pumps and climate control can exceed the incoming supply rating - dynamic load balancing prevents this automatically.
A current transformer installed on the main incoming tails measures total property current draw in real-time and feeds this data to both the battery inverter and the EV charger simultaneously. Both devices respond by modulating their charge rates to keep total simultaneous demand within the supply limit. When high-draw appliances cycle off, the chargers automatically increase back to maximum output.
Modern large-format EVs carry substantial battery capacity - more than enough, through Vehicle-to-Home technology, to contribute meaningfully to household energy supply when bidirectional chargers become widely available.
Vehicle-to-Home technology requires specific consumer unit earthing topology, dedicated bidirectional charger circuits, and cable sizing capable of handling bidirectional high-current AC flow. We design and install every combined battery and EV charger system with this future capability pre-engineered into the infrastructure. When V2H chargers become widely available for premium EV platforms, your estate's electrical architecture will support them without structural rework.
The home battery component of a combined installation may qualify for 0% VAT under HMRC energy-saving materials rules, subject to current HMRC rules and confirmation at quotation, which where eligible reduces the project cost at invoice with no application or registration required.
The aesthetic standard of the installation must match the standard of the property. EV charger cable routes are surveyed through building fabric before any work begins - roof voids, internal wall cavities, and underfloor channels where possible. The charger unit itself is specified for architectural compatibility: zappi for solar-diversion capability, Andersen A2 for heritage and period properties, or Tesla Wall Connector for Tesla owners requiring full vehicle integration.
"Tesla Powerwall 3 and a zappi EV charger installed together as one programme. The dynamic load balancing was explained clearly before installation - we have a heat pump and an induction hob and the team confirmed our supply rating needed it. The Octopus Intelligent configuration was set up on commissioning day. Charging the Model Y overnight now costs under 1 GBP. The combined saving versus what we were paying before is running at nearly 200 GBP per month."
"We have a Porsche Taycan and wanted a system that would charge it as cheaply as possible without solar. The GivEnergy AIO battery and the Andersen A2 charger were installed in a single day - no visible cabling anywhere. The Octopus Intelligent setup means both the car and the home battery fill overnight automatically. The Andersen unit suits the property perfectly - we were told by a neighbour they hadn't noticed we had a charger at all."
.png?updatedAt=1769292486318)
Octopus Go provides a fixed off-peak window from 00:30 to 04:30 at a set rate. Octopus Intelligent provides a 6-hour window from 23:30 to 05:30 with flexible scheduling - the API actively manages your EV charger and home battery to optimise both charge sessions within that window, responding to dynamic pricing within the period. For a household charging both a premium EV and a home battery simultaneously, the 6-hour Intelligent window provides more scheduling flexibility and typically delivers 15 to 20 percent lower overnight charging costs than a fixed 4-hour Go window.
A standard UK residential single-phase 100A supply has a practical simultaneous capacity limit of approximately 23kW. A 7.4kW EV charger operating with a 5kW battery, a 9kW heat pump, and a 3kW underfloor heating zone already totals 24.4kW - over the safe limit. Without active CT-sensor dynamic load balancing, this combination blows the supply fuse. With it, the chargers automatically step back to accommodate the other loads and return to full output when they cycle off. This is not an optional safety feature for a large Surrey estate - it is a fundamental requirement of a correctly engineered installation.
A home battery and EV charger installation without solar can be a strong standalone investment for households with a large EV. The combined reduction in energy costs from off-peak overnight charging of both the vehicle and the home battery - versus standard daytime grid rates - can be significant, depending on vehicle battery size, annual mileage, household consumption, tariff structure and future energy prices. The home battery component may qualify for 0% VAT under HMRC energy-saving materials rules, subject to current HMRC rules, which where eligible reduces the project cost at invoice. Payback period depends on all of the variables above and is modelled at survey stage, not quoted as a fixed figure.
Some residential solar, battery storage and qualifying energy-saving installations may be eligible for 0% VAT, subject to current HMRC rules and confirmation at quotation. This can apply to standalone home battery storage regardless of whether it is installed with or without solar panels, and regardless of whether an EV charger is included in the same project. Where eligible, the zero rate applies to the battery module, inverter, mounting hardware, cabling, and installation labour. The EV charger element of the project is invoiced separately at the standard 20% VAT rate - we itemise both elements clearly and confirm the applicable VAT position at survey and quotation stage.
Yes, when the system is correctly engineered with active dynamic load balancing. Without DLB, simultaneous operation of a 7.4kW EV charger, a 5kW battery, and typical luxury estate loads can easily exceed a standard single-phase 100A supply limit. A CT sensor on the incoming supply tails measures total property demand in real-time and feeds this data to both the battery inverter and the EV charger, which modulate their charge rates to ensure the combined load stays within the supply rating at all times. We assess your specific supply rating and estate load profile during the pre-installation survey and design the DLB configuration accordingly.
The combined reduction in energy costs from coordinated overnight charging of both the EV and the home battery - compared to standard daytime grid rates - can be significant for households with a large EV and daily battery cycling. The actual figure depends on vehicle battery size, annual mileage, household consumption, the prevailing off-peak tariff rate and future energy prices. These factors are modelled at survey and quotation stage rather than quoted as a fixed or typical annual figure.
Vehicle-to-Home technology can allow a compatible EV battery to discharge stored electricity back into a property, supplementing a home battery. A large-capacity EV such as a Porsche Taycan carries substantial usable storage that, where vehicle, charger and home system are compatible, may provide meaningful backup over several days. V2H requires specific bidirectional charger hardware and consumer unit infrastructure, and compatibility must be confirmed before specifying a V2H-ready installation. While V2H chargers for premium European vehicles are not yet widely available in the UK, we design every combined battery and EV charger installation with the earthing topology and cable sizing that these systems will require, so the property can support V2H hardware when it becomes available without structural rework.
Make the most of what you generate. Without a battery, a significant share of solar energy is typically exported back to the grid at low rates.
With a properly sized battery system:
"A battery transforms your home from a passive energy consumer into an active energy hub."