What Size Home Battery Do I Need?

Why Home Batteries Are Becoming So Popular

With rising energy prices, more homeowners are turning to battery storage to take control of their electricity costs. Whether you have solar panels or not, a home battery can help you:

✅ Save Money – Store energy when it’s cheap and use it when prices are high.

✅ Maximise Solar Power – Reduce reliance on the grid by using stored solar energy at night.

✅ Gain Energy Independence – Reduce the impact of power cuts with backup power.

✅ Lower Your Carbon Footprint – Use more of your own renewable energy.

The Smart Choice for Homeowners

Batteries allow you to take advantage of smart tariffs and solar energy, helping you future-proof your home against rising electricity costs.

👉 Heat pump owners can benefit even more! Since heat pumps run on electricity, a battery can help reduce heating costs by using cheaper, stored energy rather than expensive peak-rate electricity.

So, what size battery do you need? Let’s break it down.

Step 1: Understand Your Energy Usage

To choose the right battery, consider:

🔹 Your daily electricity usage (from your energy bill or smart meter).

🔹 When you use the most power (day vs night).

🔹 If you have solar panels and how much excess energy you generate.

🔹 Whether you want backup power for outages or essential appliances.

✅ For heat pump owners: A battery can help you store energy during cheap off-peak hours and use it to run your heat pump efficiently.

Step 2: Define Your Battery Storage Goals

Your Goal	Battery Sizing Guide
Maximise solar self-consumption	Match your daily excess solar production.
Reduce peak electricity costs	Store enough energy to cover evening usage.
Backup power for outages	Size for essential loads (fridge, lights, internet, heating).

💡 Heat pump users on time-of-use tariffs should consider a battery that covers heating demand during expensive peak hours.

Step 3: Estimate Your Battery Size

Scenario	Suggested Battery Size
Small home, evening usage 3-4 kWh	5 kWh battery
Medium home, evening usage 6-8 kWh	7-10 kWh battery
Large home, higher usage or backup power	10-15 kWh battery
Off-grid or full backup needs	20+ kWh battery

🔹 Important Note: Most batteries allow 80-90% of their total capacity to be used. A 10 kWh battery typically provides 8-9 kWh of usable energy.

🔹 Heat pump owners: Your heating demand can vary seasonally, so factor in additional battery capacity if needed.

Step 4: How Smart Tariffs & Battery Storage Work

Smart tariffs (also called time-of-use tariffs) charge different rates for electricity depending on the time of day.

Batteries help you take advantage of this by storing cheap electricity and avoiding expensive peak rates.

Examples of Smart Tariffs in the UK:

🔹 Octopus Intelligent / Go / Flux – Offers very cheap off-peak rates.

🔹 OVO Charge Anytime – Discounts electricity when demand is low.

🔹 EDF / E.ON Dynamic Tariffs – Pricing changes based on the grid.

How a Battery Saves You Money:

⚡ Charge up when rates are low (e.g. 1am-4am).⚡ Use stored energy when rates are high (e.g. 4pm-7pm).

⚡ Reduce reliance on expensive peak grid power.

🔥 For heat pump owners: Run your heat pump using stored off-peak energy to slash heating costs!

Step 5: Consider Future Needs

✔ Planning to expand your solar system? Choose a modular battery that allows future upgrades.

✔ Want a battery that lasts? Look for a 10-15 year warranty for long-term savings.

✔ Need full backup power? Some batteries can power essentials (fridge, heating, lights) during power cuts.

Step 6: Is a Battery Right for You?

☑ Do you regularly export solar energy to the grid?

☑ Do you use electricity in the evening when solar isn’t generating?☑ Do you want to save money by using stored energy when prices are high?

☑ Do you need backup power for critical appliances?

☑ Do you own a heat pump and want to reduce your heating costs?

👉 If you answered yes to any of these, a home battery could be a great investment.

Want a Personalised Recommendation?

🔹 We can analyse your energy usage to help you find the perfect battery size.

📩 Get in touch today to future-proof your home and start saving!

Final Thoughts

Adding a battery to your home can cut energy bills, boost solar savings, and help heat pump owners make the most of smart tariffs. 

Whether you want to lower costs, reduce grid reliance, or have peace of mind during power cuts, the right battery can make all the difference.

📞 Contact us today to find out how much you could save!