Wholesale energy prices explained: how your home battery can play the market.

If you have solar panels and a home battery, you’re already doing something brilliant. You’re generating your own electricity, storing it, and cutting your reliance on the grid. But there is a good chance your battery is not working nearly as hard as it could be.

The reason comes down to how most energy tariffs are structured. Right now, the vast majority of households pay a flat rate for electricity. It goes up when Ofgem adjusts the price cap, and that’s about as dynamic as it gets. But behind that flat rate, something far more interesting is happening every single day.

The wholesale electricity market moves every 30 minutes. And if your battery could respond to it, you could be saving (and making!) a lot more money.

What is the wholesale energy market?

When energy suppliers buy electricity, they don't pay a single fixed price. They buy it on the wholesale market, where the price for each half-hour of the day is set separately.

Here's how that price actually gets set. For each half-hour, available generators are stacked up from cheapest to most expensive, and brought online in that order until there's enough power to meet demand. The price that every generator in that half-hour receives is the price of the last, most expensive one needed. Ofgem calls this the marginal price. Cheaper sources are used first, but the price for a given time is set by the most expensive type of electricity that has to be running.

The practical effect is that the wholesale price moves around a lot through the day. When demand is low and there's plenty of cheap generation available, the marginal generator is cheap and prices stay low. When demand rises, more expensive plant is added to the mix to keep supply matched with demand, and the price climbs to match. Same market, same mechanism, very different prices half-hour to half-hour.

For solar and battery owners, the interesting part is what happens at the bottom of the range. When low-cost generation is plentiful and demand is light, wholesale prices can fall to very low levels, and on occasion they go negative, meaning the market is effectively paying buyers to take electricity. Negative pricing has become more common in Great Britain as more wind and solar have come onto the system. A home battery that knows when those windows are happening can buy cheap, store it, and use or sell it when prices climb again later in the day.

Why your current tariff ignores all of this.

Standard energy tariffs smooth everything out. Your supplier buys electricity at various prices and time periods across the market (known as “hedging”), averages it all out, adds their margin, and charges you a single unit rate. You never benefit from the cheap periods, but you are also never exposed to the most expensive costs. You pay the same whether electricity costs a fortune or next to nothing.

It’s a bit like a hotel that charges the same nightly rate regardless of whether it is peak season or a quiet midweek in November. Predictable, sure. But not exactly working in your favour if you can be a little bit flexible.

The Smart Export Guarantee (SEG) often works similarly. Most SEG tariffs pay a flat rate for any surplus energy you send back to the grid, regardless of what that energy is actually worth at the time you export it. On a sunny afternoon when wholesale prices are high, you could be earning far more. Either way, with a flat rate you have no visibility and no ability to respond.

How Next Optimise changes the equation.

Next Optimise connects your home battery directly to half hourly wholesale and so-called “non-commodity” prices. Instead of a flat rate, the system sees the actual cost of electricity every 30 minutes and automatically acts on it. The system looks ahead at the prices over the next 24 hours, forecasts your solar generation and likely consumption, and then makes a plan for how to minimise your costs in that time window.

When prices are low, your battery charges up. When prices rise, your stored energy powers your home rather than drawing from the grid. When prices are high enough, the system may choose to export that stored energy to the grid and earn you credit. You don’t have to watch it happen. You don’t manage it. The algorithm handles every decision, around the clock, even when you are asleep or on holiday.

This is not guesswork. Next Optimise uses intelligent software developed by Amber Electric, our technology partners in Australia, who have been running this exact system across more than 80,000 homes. The UK energy market has its own characteristics, but the core logic is the same: find the cheap windows, fill the battery, use or sell that energy when the price is right.

What negative prices mean for you.

When prices go negative, Next Optimise is likely to charge your battery as fast as it can. It’s filling up on electricity that the grid is effectively giving away, ready to use when prices climb back up.

The more volatile the market, the more opportunities the system finds. And right now, the UK market is particularly volatile. Energy prices have climbed sharply on the back of geopolitical tensions, and renewables are coming online faster than ever, on a grid that wasn't built for them. That creates bigger swings and more frequent windows where smart automation genuinely pays off.

What the numbers look like in practice.

Before launching Next Optimise, we piloted the technology with real UK households under the name Next Solar Max. The results were clear. Every single participating household saw a reduction in their bills. On average, customers saved around £18 a month. Some saved close to £100. One household saved £27 in a single week during a period of sharp wholesale price swings.

Modelling suggests households could save close to £300 a year on top of what they would already earn from a standard Smart Export Guarantee. Those are not projections built on perfect conditions. They’re based on real homes, running the system through real UK market conditions.

Your battery can do more than you think.

A home battery sitting on a flat tariff is a fairly blunt instrument. It charges from excess solar, or when it is scheduled to, uses what it stored, and that is roughly that. The hardware in your home is capable of so much more.

Next Optimise turns the same battery into something that is actively responding to the market every half hour of every day. The wholesale price swings that most households never see, and certainly never benefit from, become the engine that drives your savings.

If you have solar panels and a home battery and want to find out whether your setup is compatible, get a quote to see if you're a good fit.

Please note that savings figures are based on data from our early pilot and modelled projections. Actual savings will vary depending on your energy usage, equipment, tariff, and market conditions. Past performance is not a guarantee of future savings.