This week and last, causing a stir across the energy world, we’ve had a glimpse of the future.

It’s been particularly sunny and windy, causing energy prices to go negative. In other words, energy buyers and consumers have been being paid rather than paying to use energy. Events that flip the energy market on its head like this are becoming more common, but why do they happen?

Negative energy prices

It’s all down to the way different technologies work together in our energy system. Many solar and wind farms operate with financial support based on how much they generate, and it can be awkward and expensive for nuclear and large thermal power stations to turn off for short periods. This means that on particularly sunny and windy days with low electricity demand, such as a hot lazy Sunday afternoon, it can become more expensive to ask generators to turn off than to ask users to “turn up:” prices go negative, allowing those who can react to it to be paid for soaking up all that excess power from the grid.

That’s where Powervault comes in!

Powervault and Octopus Agile

Over the past 12 months Powervault batteries have been running on the Octopus Agile tariff. With this revolutionary tariff, customers receive a new price for electricity every half an hour, all year round, depending on what’s happening in the energy market. If the cost of supplying power goes up, the price you pay goes up (with a cap just in case), and if the cost goes down, the price you pay goes down. And if the price goes negative, like last Sunday, Octopus pay you to take the energy.

“I love watching my battery do all the hard work on days like Sunday.” said Jeff Hardy, a Powervault customer on the Octopus Agile tariff. “I now think of my home as a mini-power station, tuning our demand to suit the wider energy system’s needs. That said, it still feels a bit odd that I’m importing more power than I used to, but my bills have gone down.”

The Powervault 3 uses clever demand prediction and weather forecasting to learn about your personal power usage. Coupled with Octopus Agile it works out the best charge / discharge schedule for the Powervault every day – a ‘Smart Schedule’ – which allows our customers to get the very lowest prices for electricity available on the market, and avoid the expensive period in the evening.

For the first time the Smart Schedule allows customers both with, and without solar save on their energy bills using a battery. Modelling based on an ‘average’ customer’s usage without solar suggests savings of up to £270 to 580 per year* are possible by switching to Agile and installing a Powervault.

What’s more, for customers like Jeff, Octopus also have an Agile tariff for exports to the grid. This means that any power sent out to the grid from the solar or Powervault also has a new price every half an hour. On days like Sunday when electricity prices are negative but export prices stay positive, our algorithm goes to town. Powervault batteries across the country kick into action, charging and discharging to balance the energy markets while reducing our customer’s bills.

“It’s been fascinating to see my Powervault charging and discharging to the grid, while I’m paid each way, and that it always then charges to full afterwards so that I avoid peak prices in the evening,” added Jeff.

The future of energy today

To avoid dangerous climate change and make the most of a clean energy revolution and sustainable economy, we need to quickly change to a 100% clean energy system. As the amount of solar and wind generation we have increases, days like last Sunday are becoming more common.

Until today the traditional use for a battery has been capturing any excess solar power you can’t use now and storing it for later: reducing your dependence on the grid. Powervault’s vision is maximising interaction with the grid to benefit the system as whole, and rewarding our customers in the process.

Instead thousands of homes using and generating energy in isolation, we see an interconnected network of smart batteries, electric heat, electric vehicles and renewable energy working together to provide 100% clean energy at a more affordable price. And the data from last weekend shows this isn’t as futuristic as it sounds, but is happening today!

We are now offering an exclusive £500 discount of to all new Powervault 3 customers with Octopus Agile. To find out more, get in touch! We’re here to help and would love to hear from you.

Enjoy seamless integration of renewable energy into your home or business with Powervault. Get a quote now.

* The precise performance of a battery is difficult to predict with certainty as each home is different. Powervault’s battery models use industry standard demand profiles used by Ofgem to simulate an average domestic customer (PC1). The range £270 to £580 is based on modelling of customer profiles without solar and with demand of 3,100 to 8,000kWh per year. The savings calculate the savings of switching from a standard £0.16p/kWh single rate tariff to Octopus Agile, as well as the modelled benefit of charging and discharging the battery using Powervault’s Agile optimisation algorithm.