Maximising your home battery storage (with or without solar panels)

A home battery system with or without solar panels can provide a number of financial benefits, particularly through energy trading and cost savings strategies. Here’s how...

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Time-of-use (TOU) or arbitrage

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Many energy companies offer time-of-use (TOU) tariffs. With these tariffs, electricity costs can vary in bands throughout the day/night. Rates are typically higher during peak hours (4–7pm) when demand is high and lower during off-peak hours (11pm-5am).

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A home battery system allows you to charge the battery during off-peak hours when electricity is cheaper, and then use that stored energy during peak hours when electricity is more expensive. This strategy, known as TOU or arbitrage, can significantly reduce your electricity bills.

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For example: a Tesla Powerwall has 13.5kWhrs of battery capacity. If you charge it at night on a TOU tariff (like Octopus Go) between 1am and 5am, your electricity is priced at just 8p per unit (or 8p per kWhr). As the Tesla can store 13.5kWhr, this costs 13.5 x 8p = £1.08. When the cheap night rate period finishes at 5am, the battery automatically and dynamically discharges to cover just the needs of your house. So instead of buying electricity at the typical day rate of 32p per unit, you get to use the energy you bought at 8p, meaning you have a saving or delta of 24p per unit. This adds up to 13.5 x 24p or £3.24 each day - assuming you use the full 13.5kwhrs each day. Over a year, this equates to £1182.60 in savings!

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This is the simplest and most obvious benefit of a home battery with or without solar (solar would provide an even better return due to free charging and also export payments where your supplier buys surplus power from you!)

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The second less obvious way to financially benefit from a home battery is to leverage it against half hourly pricing tariffs and trade through the battery (Buy low, sell high).

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How does that work?

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In the UK, electricity is actually sold at a different price every 30 minutes (half hourly billing) and it's priced according to supply and demand. So historically, electricity retailers like EDF and EON would average these prices out, first over 24 hours, then over a month, and then over a year. They'd put their margin on top and sell you electricity at fixed unit price.

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With the advent of smart meters it is now possible for consumers to access these half hourly rates through what Octopus and others call “intelligent” tariffs. This means you could potentially buy electricity at 1p a unit and sell it for up to £2 a unit, depending on the supply and demand on a given day. Of course not all home battery manufacturers have the capability of accessing these intelligent tariffs and also trading for you, but GivEnergy and Tesla, two of our main strategic partners do. You just select the relevant tariff with your provider and then select that tariff from a drop down menu within the home battery system manufacturers' app. The system will choose when to buy, hold, trade or just dynamically discharge into your home.

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Another tip - backup power during outages

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While not a direct financial benefit in day-to-day operations, having a home battery system can provide backup power during outages. This can prevent financial losses associated with power outages, such as spoiled food, or lost work productivity (if working from home). In our experience, only Tesla Powerwall and GivEnergy All in One solutions offer back up on grid failure as standard. Most other systems can make it available, but it will require additional hardware at a cost. If back up is important to you, please be sure to mention this to your chosen supplier (such as us!).

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Finally, some grid operators offer incentives for homeowners who allow their batteries to participate in grid services, such as frequency regulation or demand response. While this isn't universally available, it can provide an additional income stream where it is.

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Conclusion

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While the most significant financial benefits of a home battery system are typically realised when paired with solar, there are still notable saving opportunities without solar through TOU arbitrage, demand charge management, and backup power advantages. The exact financial benefit will depend on your local electricity rates, utility policies, and energy usage patterns.

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How do you get this set up? Simply ask your supplier for a tariff suitable for a home battery system with a low night time rate. Once you have this give us a call on 01621 983135 or send us an email to service@stagsolar.com and we will talk you through setting your system up or if you prefer we will set it up for you remotely.

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Contact us for more money saving and money making tips.

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