Revolutionising Energy Management: Mixergy and Grid Flexibility

November 10, 2023

The move towards electrification in Europe is well underway. Governments across the continent are bringing forward legislative measures and funding incentives that drive the uptake of electric domestic assets, such as heat pumps instead of gas boilers and electric vehicles instead of internal combustion engine (ICE) cars.

At a macro energy supply level, pressures on international natural gas supplies and increased energy supply risk are driving the implementation of renewable energy supply. Combined, we have a recipe that causes our network operators some real challenges.

The challenge

We have an increasing demand for electrical power across the grid, with an increasingly unpredictable supply system and a growing reliance on solar and wind.

To address the need for additional energy storage and grid infrastructure upgrades required for Europe to achieve net zero, BloombergNEF (BNEF) projects a massive $32 trillion investment will be necessary by the year 2050. With many storage projects delayed, exploring alternatives (such as utilising the assets in our homes to aid in this transition) may be worthwhile.

The imbalance between supply and demand is driving the growth of the grid flexibility market, whereby market forces try to help both the grid use more renewables and the demand side use more clean electricity.

These market forces were traditionally handled by demand side response (DSR) aggregators who would negotiate contracts with large power consumers (such as large factories, etc.)  whereby the factories would power up or down in response to the changing needs of the grid in exchange for a fee.

However, with the growing adoption of electrical assets in homes across Europe, the power is shifting towards a consumer-centric flexibility market. A contract with a large aluminium smelting factory compared with an agreement with thousands of householders is a very different proposition.

As this market is developing, more and more bodies are engaging to make access to flexibility as convenient and valuable (for all parties) as possible.

One body representing this market is SmartEn – a European business association integrating the consumer-driven solutions of the clean energy transition. Mixergy are proud members of SmartEn and hope to contribute to the equitable development of the flexibility market.

What is Mixergy’s role in this?

Mixergy’s mission is to develop sustainable technology solutions that provide the best interaction between homes and the grid to save carbon, lower costs, and maximise comfort. It is clear, then, that Mixergy is a key stakeholder in this energy transition and in helping the consumer play a part.

Why Mixergy, and what can we do to help?

Mixergy develop smart cloud-connected hot water solutions that do a whole host of cool things, but specifically around  flexibility, there are a few points worth highlighting:

  • Water has a thermal capacity, meaning it takes a lot of energy to heat up and cool down , making it an ideal energy store.
  • Hot water cylinders typically store between 90-300L of water, equivalent to 9-15kWh of energy storage (if lifting the water temperature by 40 degrees).
  • Each hot water cylinder has a 3kW immersion, which can be powered on very quickly.

When we consider all of the above and the fact that Mixergy’s smart controller measures frequency (Hz), voltage (V) and power (kW) and can connect and communicate these data points quickly via an API at a cloud level, we have the perfect recipe for a grid response tool.

Large energy store + quick response + ease of communication = perfect flexible energy asset

The Mixergy X, Solar X and iHP X
Mixergy hot water cylinder line-up

Of course, the Mixergy hot water cylinder does not store electricity as electricity, nor can it be converted back to electricity. The electrical energy is converted to hot water, which the household then withdraws in the form of showers and baths!

This means that the Mixergy hot water cylinder (and hot water cylinders in general) can only provide certain services to the National Grid operators.

Mixergy cylinders are a brilliant tool for flexibility as they are so scalable – for every 330x Mixergy cylinders installed, another 1MW of flexible load is added to the grid.

People need hot water in their homes, so we are not adding an asset that adds no value beyond flexibility; it is helping customers lower their hot water bills and their carbon impact whilst unlocking flexibility.

Every Mixergy cylinder variant can be used for grid flexibility, be it an indirect/gas boiler, heat pump or solar PV model. This is possible because they all have our smart controller and 3kW immersion present.

Figure 1: Graph to show a small, seemingly insignificant power spike on a Mixergy cylinder. This small and fast spike in energy consumption is an FFR or ‘Frequency Response’ event, where the Mixergy cylinder immersion powers on for a short period to help the National Grid reduce frequency levels caused by excess renewable energy on the grid.

Mixergy customers can opt in to supporting the grid, by enabling or disabling grid services within the ‘Tank Settings’ menu within the Mixergy app; as shown in Figure 2 below:

Figure 2: Mixergy app tank settings

How big is the hot water market, and what is the opportunity?

In the UK, there are approximately 10 million homes with hot water cylinders, and around 500,000 hot water cylinders are installed (new + replaced) every year.

If these 500,000 hot water cylinders were connected to the grid, that would provide 1.5GW of flexible ‘power on’ load and about 5GW of flexible storage.

For comparison, the UK’s largest purpose-built battery energy store, operated by TagEnergy and Harmony Energy, has 196MWh of storage – enough to power 300,000 homes!

Therefore, we could install 25x that capacity in one year if all hot water cylinders in the UK were smart connected Mixergy cylinders! All without the need for additional land, buildings, rare earth minerals, etc.

Hot water cylinders can also be put through unlimited charging cycles without any degradation in performance, unlike conventional batteries, whose performance diminishes over time.

As a comparison, a stainless-steel hot water cylinder often comes with a 25-year warranty; the market-leading domestic battery today (Tesla PowerWall) only has a 10-year warranty.

For the above reasons, Mixergy is passionately pursuing its mission of providing the best interaction between the grid and the home. We believe it can be achieved in a way that all parties benefit. Lower bills, better control, increased visibility, better utilisation of renewables… all whilst increasing grid flexibility at a lower cost than a domestic battery.

As if that wasn’t enough good reason to drive the adoption of Mixergy, each one has the potential to control and optimise other assets within the home, making ‘dumb’ devices ‘smart’ – this is the next evolution in Mixergy’s business model and consumer value proposition… so watch this space for exciting releases soon!

Mixergy’s business development team are working with enterprise partners across Europe to realise the potential of flexibility whilst offering their customers a better hot water experience.

Please contact us if you would like to learn more about the range of solutions in this space.