Battery energy trading allows British businesses to earn income from their stored or surplus energy, providing a greater return on their investment in their on-site assets. For companies reporting ESG positions to investors, shareholders and customers, it’s a clear demonstration of the practical action being taken on energy use and renewable power adoption.
In this article, we explain how battery energy trading works and the financial returns it can deliver to your business.
What is battery energy trading?
Battery trading typically takes one of two forms:
- You generate solar power, store it in your battery, then sell it back to the grid (known as exporting) when prices are high.
- You buy electricity from the grid when prices are low or negative, store it in your battery, then sell it when prices are high.
The income you make is the spread or difference between what it cost you to charge up your battery and how much the grid paid to buy it from you. You may also hear this called energy arbitrage, battery arbitrage or power trading.
Trading is one of two routes to value from your battery
The deal you have with your electricity supplier determines how your battery makes money. Most businesses are on one of two kinds of deal:
1. Standard fixed-rate or time-of-use tariffs
You pay either a fixed rate per unit for the duration of your contract, or a predictable rate that changes by time of day.
Your battery charges up when electricity is cheaper, then discharges later to power the site during periods when electricity is more expensive. Savings come from having to buy less from the grid. When spare solar is worth more on the wholesale market than under your normal export rate, the battery sells that power through the P415 trading route.
The battery cuts your bill by powering the site with stored cheap electricity, and the trading service earns separate income by delivering power when the market needs it..
Example: A commercial site with solar and a battery is on a time-of-use tariff: 25p per unit during the day, 12p per unit overnight.
Overnight, the battery charges at 12p. During the day, it discharges to power the site, replacing electricity that would have cost 25p. The site saves 13p on every unit the battery shifts.
Around midday, the solar panels produce more electricity than the site can use. Some of the surplus goes to the battery for later. The rest could be exported at the site's standard rate of, say, 8p per unit. But if the wholesale market price is 15p per unit that half-hour, the battery sells the surplus through P415 instead, earning 7p more per unit than the standard rate would have paid.
2. Wholesale-linked tariffs (like Octopus Agile)
The rate you pay moves up and down with market prices through the day. The return here comes from the gap between the cheap price you pay to charge the battery and the high price you would otherwise have paid for grid electricity to run the site.
You're unlikely to sell any electricity back to the grid with this arrangement for a few reasons:
- P415 trading needs a stable battery schedule to deviate from. On a wholesale-linked tariff, the battery changes its behaviour every half-hour to match the prices. The trading service can't earn money without a regular pattern to work from.
- Your storage capacity is enough to run the site through the expensive hours, leaving little or nothing left to sell.
- At most times, using the stored power yourself saves more than you'd earn from selling it.
Example: A commercial site with solar and a battery is on Octopus Agile. On a windy spring day, prices drop to 6p per unit between 1am and 5am, while the evening peak between 4pm and 7pm costs 35p per unit.
The battery charges from the grid in the cheap overnight window at 6p. During the evening peak, it discharges to power the site, replacing electricity that would have cost 35p. The site saves 29p on every unit shifted from peak to off-peak.
On a day when the evening peak is even higher, the savings are even bigger. On a calm winter day when overnight rates only drop to 18p, it's smaller. The cheap and expensive moments change throughout the day, so the software running the battery has to watch the prices and switch it on or off at the right time.
In this article, we’re focusing on the trading route in more detail and we’ll come back to how the returns compare later on.
How battery trading works in Great Britain
Very few companies trade the market themselves. Instead, they use a specialist partner who watches the wholesale market and trades on your behalf, so you can earn income without having to learn how the markets work yourself.
They generally use trade in these three markets:
- Day-ahead market: Participants buy and sell electricity for next-day delivery in half-hour blocks. Prices are set through an auction that clears each afternoon.
- Intraday market: This operates closer to real time, typically a few hours before delivery. It captures price movements that take place after the day-ahead auction. These late changes in price often follow updated weather forecasts or unexpected changes in supply.
- Balancing mechanism: This is the final market, run by the National Energy System Operator (NESO). It accepts bids and offers to keep the electricity system balanced in real time. Prices in this market can move sharply when supply and demand are tight.
They get the best results by picking the market paying the best price minute by minute. So, in a single day, a firm might:
- Sell into the day-ahead market in the morning
- Switch to the intraday market in the afternoon
- Help balance the grid in the evening
The reason you can’t do this yourself is regulatory. Only registered parties can take positions in GB’s wholesale markets. You may hear them referred to as Virtual Lead Parties, battery optimisers, aggregators, flexibility providers, route-to-market providers. They all do the same core job for your site.
Whichever provider you work with, they need to plug their software into your battery, so they can monitor:
- How full the battery is
- How much electricity your site needs
- What prices are doing in the markets
- What the weather's about to do
The software uses all of this information to decide whether the battery should charge up, power the site, or sell energy back to the grid.
What affects your trading income
Once your system is up and running, the day-to-day process is hands-off. Several things affect the level of income your battery actually earns:
- Battery size: More capacity and a higher power rating create more trading opportunities.
- Market conditions: The sharper the price movements, the more value there is in charging low and selling high.
- Software quality: Better optimisation reacts more intelligently to price, weather and site demand.
And several things can pull your earnings down:
- Site demand: When your site needs the stored power, the battery may cover that demand rather than trading.
- Export permissions: Most sites have limits on how much they can sell back to the grid.
- Revenue share: Your provider keeps a percentage of trading income as their fee.
What can your battery earn?
GB battery revenue benchmarks are usually shown as £/MW/year, based on the battery's power rating rather than its storage capacity. For example, a 100 kW battery is 0.1 MW.
In June 2025, GB battery energy storage systems earned an annualised £76k/MW. In October 2025, the benchmark reached £77k/MW/year. By December 2025, it had fallen to £47k/MW/year.
For a 100 kW battery, those benchmark rates equate to roughly £4,700 to £7,700 a year. That is before optimiser fees, revenue share, losses, degradation and site limits. Larger batteries can earn more, especially when price gaps widen and the optimiser keeps capacity available for the right moments.
Your site may not achieve these benchmark rates exactly, as behind-the-meter batteries face limits such as export caps, warranty rules, site demand needs and metering constraints. But they give you a useful indication of what battery trading can be worth in practice.
The two parallel routes produce different kinds of return, either wholesale trading on a standard tariff, or tariff optimisation on a wholesale-linked tariff. The figures behind them aren't directly comparable:
- On the trading route (standard tariff): Using the £47k to £77k/MW/year benchmarks above, a 200 kW battery could earn roughly £9,400 to £15,400 a year in wholesale market revenue. This is revenue against your current fixed-tariff bill, before fees, revenue share and site limits. In addition to the trading revenue, the battery will help reduce your bills by using more off-peak energy and excess solar if available.
- On the wholesale tariff optimisation route (Agile or similar): GridVolt modelled a 200 kW battery on a synthetic 620 MWh commercial load profile against nine months of Octopus Agile data (April 2024 to January 2025). The model shows a saving of around £26,000 a year. This is the saving compared to the same site running on Agile without a battery, not against a fixed tariff.
Which route works best for you depends on your tariff and how your site uses electricity. The two figures are not guaranteed, and you can't add them together. They show what two different setups can earn instead of one combined return.
Why choosing the right software makes a difference
Two batteries with the same hardware and on the same site can earn very different amounts. The difference is in the software.
Basic battery software follows the same fixed daily schedule of charging overnight and discharging during the day. That will save you money but it won’t maximise your savings. That’s because the cheapest and most expensive hours in the day move around. If a fixed schedule doesn’t mirror these changes, then you miss the cheapest moments and pay for the expensive ones.
The best software monitors the wholesale market, weather conditions, solar generation and your site’s actual usage in real time. It then replans its day to factor in these inputs so you catch the cheapest prices and avoid the most expensive ones. GridVolt’s Energy Manager software, for example, forecasts site load and solar generation 48 hours ahead and re-plans every 15 minutes.
That might lead to these decisions in a single day:
- Charging the battery overnight between 2am and 6am when wholesale prices are low
- Holding capacity free in the morning if the weather forecast predicts a bright spell ahead that will produce more solar than the site can use
- Discharging into the late-afternoon peak between 4pm and 7pm, when grid electricity is more expensive
This makes a difference. A live GridVolt deployment improved battery savings by 41% over its first 70 days, compared with the same battery on standard inverter logic. GridVolt's modelling on Octopus Agile pricing shows a 200 kW battery cutting the effective electricity rate by around 40% compared to a flat rate.
How much your battery earns depends on two things: what the hardware can do, and what the software decides to do with it.
Which route is right for your site?
The right route depends on your answers to these three questions.
Are you on a wholesale-linked tariff, or willing to move to one?
If yes, tariff optimisation can work well. On a wholesale-linked deal like Octopus Agile, the price you pay rises and falls with the market through the day, and your battery charges up when prices drop and powers the site when they spike.
If you'd rather stay on your current fixed or time-of-use deal, the trading route is a better fit.
Do you want predictable bills or potential upside?
On a wholesale-linked deal, your bill rises and falls with the market. When prices spike, you pay the spike. Effective software, like GridVolt’s Energy Manager, softens the spikes by using the battery instead of buying from the grid, but it can't take them away completely.
The trading route means you can keep your current supply arrangement, with trading income coming in as a separate stream.
How big is your site demand relative to your battery?
A site that uses a lot of electricity, on a wholesale-linked deal, can save a lot through optimisation. The bigger your demand during expensive hours, the more the battery can cover with cheap stored electricity, and the bigger the saving.
A smaller site, or one without solar, may earn more from pure trading instead. The trading income you can earn depends on the size of your battery, not the size of your site.
Solar isn't a deciding factor between the two routes, but it adds value on either one. On the optimisation route, the battery stores surplus solar for use later. On the trading route, surplus solar can be sold through P415 when the wholesale price beats your export rate.
What does your site need to qualify for battery trading?
These are the minimum requirements for commercial battery trading:
| Requirement | Detail |
|---|---|
| Location | Great Britain (England, Wales, Scotland). Not currently available in Ireland |
| Meter | Half-hourly settled meter |
| Profile class | Profile class 00, which is the metering classification for half-hourly settled commercial sites |
| Battery size | Around 100 kWh or larger recommended for best performance |
| Battery compatibility | Compatible battery and inverter setup. Not all brands and configurations qualify, so this needs checking before you commit |
| On-site hardware | An energy gateway, a small on-site controller provided by the trading partner, which connects the battery to the trading platform |
If you’re not sure whether your site qualifies, ask your energy supplier, meter operator or trading provider to confirm your meter setup.
Battery energy trading with GridVolt
Most building energy management systems keep the building running safely and efficiently. They handle heating, cooling, lighting and other site loads. But they don't usually run a battery against live wholesale prices, balancing signals and site demand at the same time. That's the job GridVolt does.
GridVolt offers both routes:
- GridTrade is for businesses on a fixed-rate or time-of-use deal. It plugs into your battery through an Energy Gateway and handles selling power into the wholesale market through P415. You keep your current electricity deal, and the battery earns trading income alongside it.
- Energy Manager optimises when and how your battery charges, discharges, and works with your solar. On a wholesale-linked deal like Octopus Agile, it monitors live prices and forecasts and replans every 15 minutes to capture cheaper rates and avoid the expensive ones. On a fixed-rate or time-of-use deal, it does the same job against your tariff structure.
If you're on a fixed-rate or time-of-use deal, the two products work together on your site. They do different jobs on your battery: Energy Manager handles bill savings by using the battery at the right times, and GridTrade earns trading income by selling spare power back to the grid when the wholesale market pays more than your standard export rate.