How EV Tariffs and Battery Storage Can Reduce Your Energy Bills

If you have an electric vehicle, you may already be using an off-peak tariff to charge your car for less.

What many people do not realise is that some EV tariffs can also give your home access to cheaper electricity overnight or during specific off-peak windows.

That is where battery storage can make a real difference.

Instead of only using your cheap tariff to charge the car, a home battery can charge during the same low-cost period. It can then supply the house during more expensive peak-rate periods, helping you reduce how much higher-priced grid electricity you need to buy.

This guide explains how EV tariffs work, how battery storage uses off-peak electricity, and what to consider before deciding whether this type of setup is right for your home.

What Is an EV Tariff?

An EV tariff is an electricity tariff designed for electric vehicle owners.

In simple terms, it gives you cheaper electricity during certain periods, often overnight, so you can charge your EV at a lower rate.

A standard electricity tariff may charge the same rate all day. For example, you might pay around 27p per kilowatt hour whether you use electricity at 1am or 1pm.

With an EV tariff, the price can change depending on the time of day. You may get access to a much cheaper off-peak rate, such as around 7p per kilowatt hour, but your daytime rate may be higher.

That means the value of the tariff depends on how well you can shift your energy usage into cheaper periods.

This is easy enough for an electric car. You plug it in overnight and charge when electricity is cheaper.

But for the rest of the home, it is harder.

You can time a dishwasher or tumble dryer to run overnight, but you cannot move everything. You will still boil the kettle, cook, use lights, watch TV and run everyday appliances during the day or evening.

That is where battery storage comes in.

How Battery Storage Works With an EV Tariff

Battery storage allows you to store cheap electricity from the grid and use it later.

If your EV tariff gives you a low off-peak rate, the battery can charge during that cheap window at the same time as your car.

Then, during the more expensive daytime or evening period, the battery automatically supplies your home.

The idea is simple:

• Charge the EV on cheap electricity.
• Charge the home battery on cheap electricity.
• Use the battery during expensive periods.
• Avoid buying as much peak-rate grid electricity.

A battery storage system monitors what your home is doing. If you turn on the kettle, instead of pulling that electricity directly from the grid at the higher rate, the battery can respond and supply the demand through the inverter.

In practical terms, your home can be using stored off-peak electricity even during peak-rate hours.

If your home demand goes above what the inverter can supply, the system does not simply cut out. Any extra demand can still be drawn from the grid as needed.

That is why battery size and inverter size both matter. The system needs to be designed around how much energy your home actually uses and when you use it.

How EV Tariffs Can Help Power Your Home for Less

The main benefit of combining an EV tariff with battery storage is load shifting.

Load shifting means moving your electricity cost from an expensive period to a cheaper one.

For example, if your daytime electricity rate is around 30p per kilowatt hour and your off-peak rate is around 7p per kilowatt hour, there is a clear gap between the two.

A battery storage system can use that gap.

Instead of buying electricity at 30p during the day, the battery can charge overnight at around 7p and then supply your home later.

This does not mean the numbers will be identical for every home. Tariffs vary, usage varies, and battery efficiency varies. But the principle is the same.

• Buy electricity when it is cheap.
• Store it.
• Use it when grid electricity is expensive.

That is the core reason battery storage can work well alongside the right EV tariff.

Example: Running a Home on Off-Peak Electricity

Let’s use a simple example.

If you used 10kWh of electricity during the day at around 31p per kilowatt hour, that would cost about £3.10 per day.

Over a 30-day month, that is roughly £93.

Across a year, that would be around £1,100 in daytime electricity costs, not including standing charge.

Now compare that with charging a battery overnight at around 7p per kilowatt hour.

10kWh of electricity at 7p per kilowatt hour would cost about 70p.

Over a 30-day month, that is around £21.

Across a year, that is roughly £250.

You also need to allow for charging and discharging losses. The inverter uses power to convert electricity from AC to DC and back again, so the system will not be 100% efficient.

If you allowed for around 10% losses, that would still leave a significant difference compared with buying the same energy at a higher daytime rate.

In this type of example, the potential annual saving could be in the region of £850 to £900, depending on unit prices, system efficiency and how the battery is used.

This is not financial advice, and every property will be different. But it shows why the combination of EV tariffs and battery storage can be worth considering.

EV Tariffs and Battery Storage Without Solar Panels

You do not always need solar panels for battery storage to reduce your bills.

A battery can still charge from the grid during off-peak windows and supply your home later during more expensive periods.

This can be useful for households that already have an EV tariff and use enough electricity during peak periods to make the saving worthwhile.

In this setup, the battery is mainly relying on tariff difference.

It charges when grid electricity is cheap, then discharges when grid electricity is expensive.

Solar panels can add another layer of benefit, but they are not always required for battery storage to work.

However, standalone battery storage does depend heavily on tariff pricing. If the gap between off-peak and peak pricing changes, the return can change too.

That is one reason some people choose to add solar panels into the mix.

Battery Storage With Solar Panels

Solar panels can reduce reliance on tariff pricing because they allow you to generate your own electricity.

With solar and battery storage, excess solar generation can be stored in the battery and used later instead of being exported immediately.

This can give you more control over your energy use and reduce how much electricity you need to buy from the grid.

Solar panels also have a longer expected lifespan than most battery systems, often 25 to 30 years or more.

For some homes, especially those using a relatively small amount of electricity, solar panels may make more sense than battery storage alone.

A combined solar and battery setup can offer a more balanced approach:

• Solar generates electricity during the day.
• The battery stores excess solar or cheap off-peak electricity.
• The home uses stored energy during expensive periods.
• The system can reduce reliance on peak-rate grid electricity.

The right setup depends on your usage, tariff, property and long-term plans.

Costs vs Savings: Is Battery Storage Worth It With an EV Tariff?

Battery storage can be worth it with an EV tariff if the system is sized properly and your home uses enough electricity during expensive periods.

The return depends on several factors:

• How much energy your home uses each day.
• How much of that usage happens during peak-rate periods.
• The difference between your off-peak and peak electricity rates.
• The size of the battery.
• The size of the inverter.
• System efficiency.
• The cost of the battery storage system.
• How long the battery is covered by warranty.

As a rough example, if a battery storage system costs around £5,000 and is saving a meaningful amount each year through off-peak charging, the return on investment could sit around 5 or 6 years, depending on usage and tariff.

That does not mean every system will do the same.

It depends on how the battery is used. If the battery charges fully every day and regularly offsets expensive electricity, the saving is stronger.

If your daily usage is low, the return is usually weaker.

Battery storage is currently 0% VAT until April 2027. After that, it may move to 5% VAT, depending on future government decisions.

Battery Lifespan, Warranty and Efficiency

Battery storage is a long-term investment, so it is important to understand lifespan and warranty.

Most battery storage systems are warrantied for around 10 years.

You should also look carefully at:

• Depth of discharge.
• Usable battery capacity.
• Throughput warranty.
• Cycle warranty.
• Inverter efficiency.
• Charging and discharging losses.

Depth of discharge refers to how much of the battery can actually be used.

Throughput warranty relates to how much energy can pass through the battery over its warranted life.

Some systems may also offer stronger warranty terms than others. For example, Tesla Powerwall 3 has unlimited cycles.

Efficiency also matters.

When electricity is stored and used later, there are losses because the system converts electricity between AC and DC. Some systems, such as SigEnergy SigenStor or Tesla Powerwall 3, are often more efficient than some cheaper brands.

Even small efficiency differences can add up over time.

A Word of Warning on EV Tariffs

Not all EV tariffs work in the same way.

Some tariffs may offer cheap electricity for the whole home during off-peak windows.

Others may only apply the low rate to charging the car, while the rest of the home remains on the standard daytime rate.

This matters.

If you are planning to use battery storage with an EV tariff, you need to check whether the cheap rate applies to the home as well as the car.

Some tariffs may also require an intelligent connection to your vehicle or charger.

That could mean you need:

• A compatible electric vehicle.
• A compatible smart charger.
• A tariff provider that supports your setup.
• A system that can charge the battery during the same cheap windows.

If you are still choosing an EV or charger, it is worth checking tariff compatibility before you buy.

A smart charger, such as an Andersen or Hypervolt, may help with certain tariffs, depending on the provider and setup. In some cases, the car itself may be able to make the intelligent connection.

The important point is to check before committing.

When Battery Storage May Not Make Financial Sense

Battery storage does not suit every home.

If you use very little electricity during the day, the return can be difficult to justify.

For homes using around 1,500 to 2,000kWh a year or less, it can be hard to make battery storage stack up financially because much of the cost is in the battery system itself.

Some people still choose battery storage for futureproofing, resilience or grid independence.

That is completely valid.

But from a pounds-in, pounds-out perspective, the return may be weaker for low-usage homes.

In those cases, solar panels alone may sometimes make more sense, especially if the goal is long-term grid independence. Solar panels usually have a longer lifespan and can generate value over 25 to 30 years or more.

This is why proper design is important.

You do not want a system based only on what a calculator says. You want a system designed around your usage, your tariff and how your home actually runs.

How Much Battery Storage Do You Need?

The amount of battery storage you need depends on how much energy your home uses and when you use it.

As a simple example, if you use around 10kWh of electricity per day, then a battery and inverter setup designed around that level of usage may be enough to offset a large portion of your daily demand.

But every property is different.

You need to consider:

• Daily electricity use.
• Peak-time electricity use.
• Off-peak charging window.
• Battery capacity.
• Usable capacity.
• Inverter output.
• Whether you have solar panels.
• Whether you have an EV.
• Whether you plan to add more technology later.

Most homes do not need the biggest system available.

They need the right system for their usage.

That is why it is worth speaking to someone who can explain why a certain battery size and inverter size has been recommended, rather than simply accepting a generic system design.

Virtual Power Plants and Future Energy Technology

The way homes use energy is changing.

One area becoming more relevant is virtual power plants.

A virtual power plant allows multiple home energy systems, such as batteries or electric vehicles, to work together. In some cases, stored energy can be exported back to the grid or used to support wider grid demand.

The basic idea is that if you have stored energy you cannot use, the system may be able to send it out and pay you a premium.

This is still an evolving part of the market, but it shows where home energy systems are heading.

Battery storage, EV charging, solar panels, smart tariffs and bidirectional charging are becoming more connected.

For homeowners, that means the best system is not just about one product. It is about how everything works together.

EV Tariffs and Battery Storage FAQs