Maximise Smart Energy Savings: Charge Your Battery Cheaply Overnight & Sell Solar During the Day

Robert Harvey
May 13
4 min read

Updated: May 14

With energy bills still a hot topic and homeowners more focused than ever on sustainable living, there’s a smart way to take control of your energy use — and even make a bit of money in the process. By combining a home battery system, solar panels, and clever use of energy tariffs, you can reduce your energy bills and earn from your solar power.

Here’s how it works.

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1. Cheap Energy at Night: Charge When It’s Cheapest

Many energy suppliers offer off-peak tariffs (also known as “time-of-use” or “agile” tariffs) where electricity prices drop dramatically during the night, typically between midnight and 5am. These are designed to encourage customers to use electricity when national demand is low.

If you have a home battery system, you can schedule it to charge during this window — when electricity prices are often just 7–10p/kWh, or even lower on some tariffs. That stored energy can then be used throughout the day when grid electricity is more expensive.

Example: Charging 10kWh into your battery at 8p/kWh = £0.80
Using that energy during the day when the grid cost is 28p/kWh saves £2.00

That’s a daily saving of £1.20, or over £400 per year — just from using your battery wisely.

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2. Sell Your Solar When It’s Worth Most

If you’ve got solar panels, your system will often produce more than you can use during sunny days. That’s where the Smart Export Guarantee (SEG) comes in. Under SEG, energy suppliers pay you for each unit of electricity you export to the grid.

Here’s the key: you don’t have to get your SEG from your main energy supplier. Several independent SEG providers accept exports from solar PV systems installed by MCS-certified installers like us — no need to switch your energy supply.

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3. Top Smart Export Guarantee (SEG) Tariffs for Limitless Energy customers

Some utility companies offer higher SEG (Smart Export Guarantee) rates exclusively to their existing energy supply customers — and the good news is, they still accept battery and solar installations from independent MCS-certified installers like us.

For example, Octopus Energy's "Outgoing Agile" and "Outgoing Fixed" tariffs offer premium export rates (up to 15p/kWh or more depending on market conditions) for customers who also get their electricity supply from Octopus.

Similarly, OVO Energy and British Gas offer competitive export rates on the condition that you're a dual customer. These suppliers allow you to benefit from these enhanced rates as long as your system has been installed by an MCS-certified installer, meaning you don’t need to go through their in-house teams. This gives you the flexibility to choose a trusted local installer — like us — while still taking advantage of the best available SEG export prices.

These SEG providers accept solar and battery installations even from those whose electricity is delivered by a different utility company. So you don't have to be an existing customer to make money on the SEG:

Octopus Energy (Outgoing Lite) – 4.1p/kWh
E.ON Next – 5.5p/kWh
ScottishPower SmartGen – 5.5p/kWh
Utility Warehouse – 5.6p/kWh
So Energy – 5p/kWh
Social Energy – variable rates with additional smart features

While rates vary, any export payment is a welcome bonus — especially when your battery is topped up cheaply at night, and your daytime solar is free to sell.

CASE STUDY: How We Make the Most of Our Solar and Battery at Limitless Energy

Every night, we charge two 13.5 kWh batteries using off-peak electricity, which costs just 8p per kWh. That means we’re storing a total of 27 kWh each night at a cost of only £2.16 per day (27 kWh × £0.08). Peak time consumption of this electricity would cost us £7.56 per day (27kWh x £0.28), saving us £5.40 per day in peak electricity costs.

During the day, we generate solar power from our 13 kW array. Rather than using that energy ourselves, we export up to 3 kWh every hour back to the grid with our Octopus Agile tariff —earning 15p per kWh. In the last fortnight, we have exported more than 400kW earning £60 (400 kWh × £0.15) or £4per day. That’s money in the bank for simply making use of the sun and smart planning.

This setup allows us to:

Buy cheap electricity at night,
Sell clean solar power during the day,
Avoid peak electricity costs during the day,
And earn a return on our investment while reducing our carbon footprint.

It’s a great example of how smart energy usage and the right technology can turn a household into a mini power station.

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4. Putting It All Together: The Smart Energy Cycle

Here’s what a smart day might look like:

✅ Midnight–5am: Charge battery overnight at 8p/kWh = £0.80 for 10kWh

✅ Daytime: You use that stored energy instead of buying at 28p/kWh

✅ Sunny afternoon: Solar powers your home and exports excess at 5.5p/kWh

✅ You’re saving money and getting paid

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5. Is It Worth It?

For many households, absolutely. The more solar power you generate — and the more you shift your battery charging to off-peak hours — the greater the benefit.

And best of all, these systems are getting smarter all the time. Many modern inverters and battery systems allow you to automate this process, so you don’t have to think about it every day.

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