How half hourly settlement changed the energy market (and why it matters for your home).

Most people have no idea that a quiet rule change swept through the UK energy market a few years ago. It didn't make headlines. Your energy bill didn't mention it. But it changed the way electricity is bought and sold in this country, and it's the reason products like Next Optimise can exist at all.

The old way: usage uncertainty. 

For most of the history of the UK energy market, your energy supplier didn't really know when you were using electricity. They knew roughly how much you used across a year, based on meter readings. But the precise time of day? That was a mystery.

So suppliers made an educated guess. They looked at average usage patterns across the whole country and estimated when their customers were probably drawing power. This was called a "profile" and it meant everyone on a standard tariff was treated as roughly the same kind of customer, regardless of when they actually switched things on.

It was a blunt instrument. But for decades, it worked well enough, because the way electricity was bought and sold didn't really demand anything more sophisticated.

The problem with that approach.

Electricity isn't actually the same price all day. It never has been.

On the wholesale market, where energy companies buy the power they sell to you, prices move every 30 minutes based on supply and demand and the availability of different types of power generation. When it's a breezy afternoon and wind turbines are spinning hard, wholesale prices often drop. When millions of people get home from work and put the kettle on at the same time, prices spike as more expensive sources of generation need to get switched on. On a particularly sunny spring afternoon, when solar panels across the country are generating more electricity than anyone needs, prices can fall so low they actually turn negative. That means there's more power being produced than the grid knows what to do with, and the price signals encourage people to increase their energy usage.

These swings have always happened. But under the old settlement system, they were invisible to most households. Suppliers didn't know exactly when you were using power, so there was no way to pass those price signals through to you in a meaningful way. You paid a flat rate, the supplier absorbed the peaks and troughs, and the market complexity happened somewhere else entirely.

What changed: smart meters and half hourly settlement.

Smart meters changed the picture completely. With a smart meter installed, your supplier can see exactly how much electricity you used in every 30-minute window across the day. Not an estimate, the actual figure. However, whilst this enabled more accurate billing, this didn’t necessarily change the way energy companies bought and sold electricity.

In 2021, energy regulator Ofgem began mandating that suppliers use this data properly. Rather than relying on profiles and educated guesses, they now have to "settle", that is, account for and pay for electricity usage in genuine half-hourly slots. This is what's known as mandatory half hourly settlement, sometimes shortened to MHHS.

The rollout has been phased gradually across the market, and not every supplier has fully caught up yet. But the direction is clear: the UK energy market is moving to a world where every unit of electricity is tracked, timed, and settled against real half-hourly prices.

Why this is a bigger deal than it sounds.

Half hourly settlement might sound like a technical accounting change. In practice, it's the foundation that makes genuinely smart energy products possible.

Once a supplier knows exactly when you're using power, there are two benefits: firstly, suppliers can forecast consumption more accurately, meaning their energy purchases can be more accurate at the best prices; and secondly, they can offer you tariffs where the cost of electricity varies throughout the day, cheaper when renewable generation is high and more expensive during peak demand. It also means that if you have solar panels or a home battery, a supplier can accurately track when you're generating, storing, and exporting energy, and reward you for doing each of those things at the right moment.

Before half hourly settlement, a product that automatically trades your battery against real wholesale prices every 30 minutes simply couldn't exist in a sustainable way. The data to do it accurately wasn't there. The settlement infrastructure to price it correctly wasn't in place.

Now it is.

What this means if you have solar panels and a battery.

If you have solar panels and a home battery, this shift opens up something genuinely new.

Your battery can be charged when wholesale prices are at their lowest, often late at night or during periods when solar and wind generation is high and the grid has more electricity than it needs. It can then discharge or export that stored energy during the windows when prices are higher, typically the morning and evening peaks when demand surges.

Every 30 minutes, the conditions change. And every 30 minutes, there's an opportunity to make a smarter decision.

Doing this manually is practically impossible. You'd need to watch wholesale prices around the clock, interpret what they mean for your specific setup, and act fast enough to make a difference. Most people, understandably, don't do this. Their batteries charge on a simple timer or sit largely idle, doing a fraction of what they're capable of.

Next Optimise is built to do exactly this, automatically. It connects your home to real wholesale prices, learns how you typically use energy in your home, and makes decisions about when to charge, discharge, and export on your behalf, every half hour, all day. You don't change anything about how you use your home. The system works in the background, acting on the market signals that half hourly settlement has made visible.

What the numbers look like in practice.

During our early pilot, which ran under the name Next Solar Max, every household that took part saw some reduction in their bills. The average saving was around £18 a month compared to a modelled baseline of similar homes on the standard Smart Export Guarantee. Some households saved considerably more, with a few close to £100 in a single month. One home saved £27 in a single week during a period of sharp wholesale price swings, as the algorithm used their battery to trade energy at the optimum times.

Based on the pilot data, modelling suggests average households could potentially save in the region of £300 over a full year, on top of what they'd already receive from a standard export deal.

Savings will vary depending on your setup, your usage patterns, the size of your battery, and what the market does. But the principle is straightforward: the more the market moves, the more opportunity there is.

The technology behind it.

The automation at the heart of Next Optimise comes from Amber Electric, an Australian energy tech company whose platform already runs in over 80,000 homes across Australia, currently the most advanced solar and battery market in the world. We’ve partnered with Amber to bring that technology to UK customers for the first time.

The fact that this is a proven system matters. The algorithm has been refined across a wide range of real-world conditions and customer setups. It knows how to handle forecasting uncertainty, how to protect battery health, and how to balance the competing priorities of charging, discharging, and exporting throughout the day.

A market still catching up.

Half hourly settlement is still being rolled out across the UK market, and genuine real-time wholesale tariffs remain relatively rare. Most "smart" tariffs available today still operate on fixed time of use windows, cheaper overnight and more expensive in the evening, rather than true half hourly wholesale prices.

Next Optimise is one of the first products in the UK to combine actual half hourly wholesale pricing with automated battery control in a single package. Customers who sign up now are getting access to something the wider market is only just beginning to make possible.

Ready to find out more?

Curious if Next Optimise stacks up for your setup? Next Optimise is available to households with solar panels and a compatible home battery already installed.

Check whether your home is eligible for Next Optimise.

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.