As winter sets in and we turn up the heating to keep out the cold, lowering fuel bills becomes a challenge.
Amidst these concerns, there’s a consideration that’s often overlooked: domestic hot water consumption, something that accounts for over 17% of overall household energy consumption, as highlighted by Energy Saving Trust.
Storing energy during off-peak hours, when energy demand is lower and tariff incentives are available, can help homeowners unlock significant savings and reduce the strain on the grid. Imagine storing cheaper electricity for a minimum of 17% of your total energy consumption needs and the ripple effect it could have on your energy bills.
What is off-peak electricity?
This is when energy suppliers offer reduced rates to consumers for using electricity when demand is minimal—at designated times throughout the day or night.
But when exactly do these periods occur?
Understanding peak and off-peak hours
Peak electricity or ‘peak hours’ are the periods during the day/evening when the demand for electricity in households is higher, as homeowners prepare to go to work or school and then return in the evening, usually between 8 am and 10pm.
In contrast, ‘off-peak electricity’ or ‘off-peak electricity hours’ are the quieter hours when the energy usage is less and demand on the National grid is lower, typically overnight, between 10pm and 8am. And because the demand is lower then, the cost is less. For instance, you could pay 20p per unit of electricity during the day and 10p during the night. This type of charging is called ‘time of use’ (TOU) tariffs.
What are some time-of-use plans?
Economy 7 and Economy 10 are two common time-of-use tariffs.
Within Economy 7, homeowners get 7 hours of the cost-effective off-peak rate every 24 hours, usually provided in a single uninterrupted overnight block, typically spanning from 11 pm to 6 am. With Economy 10, homeowners benefit from 10 hours of the off-peak rate per day (typically 7 during the night and 3 during the day), potentially divided into segments throughout the day:
– 1 pm to 4 pm
– 8 pm to 10 pm
– midnight to 5 am
With smart meters installed, residents can monitor their usage and see if it is higher during ‘off-peak hours’. And even if it isn’t, with ‘time-of-use’ plans, they could strategically shift their daily electricity consumption, such as washing machine/dishwasher/EV charging/electric storage heaters, to a time when things aren’t so busy. A general rule of thumb is that if residents use less than 30% of electricity at a cheaper off-peak rate, then they’d rather make use of a single-rate tariff (a standard variable or a fixed rate one; here’s a detailed comparison).
However, the time-of-use tariff uptake is on the rise as consumer flexibility comes into focus for suppliers and latest generation of smart meters become available for homeowners.
According to a recent Guardian article, more than 10,000 households have signed up for Octopus Energy’s Agile tariff, with many reporting that they were able to cut their electricity bills by as much as 30%. Another new energy supplier, 100Green is re-offering an attractive ‘Tide’ tariff with similar off-peak benefits but at preset times (9p/kWh at nights and 40p/kWh during non-peak weekdays). British Gas, too, is now offering 50% reduction in prices via ‘PeakSave’, which runs every Sunday from 11am to 4pm until New Year’s Eve.
The figure below shows a typical demand pattern for a domestic consumer:
source: eloxon
Supercharging cost savings by ‘Hot water demand’ shifting:
How could your savings go further with time-of-use plans?
Considering that a significant portion of total household energy consumption comes from hot water usage, there are obvious advantages to using thermal storage with ultra low heat losses to store energy as heat at off-peak rates for use during the day when it is most needed. Sunamp’s Thermino heat battery can optimise and manage energy demand when coupled with time of use, effectively shifting the ‘hot water demand’ to align with cost-effective periods.
With phase change material Plentigrade P58 at its core, Thermino heat batteries store thermal energy by using the latent heat of melting & crystallising to achieve extremely high energy density. This allows the battery to store up to four times more energy per unit volume compared to standard hot water cylinders, ensuring optimal use of electricity obtained at lower cost.
Thermino significantly minimises heat losses, about a quarter of those with traditional hot water cylinders, thanks to its high-performance vacuum insulation. This high efficiency translates to minimised wastage, ensuring that the stored energy remains highly effective until used, for further savings. While a hot water cylinder may lose 1.344-3.336 kWh of heat daily, an electrically charged Thermino 210 battery has a heat loss rate of 0.77kWh/24h (a difference of up to 2.6kWh/day, which could amount to about £282 per year, depending on the unit price).
Additionally, because there’s no ‘water storage’ in a Thermino, homeowners can further save on the energy-intensive Legionella protection cycle involving timely heating of water up to 60°C.
While the Thermino battery can maximise savings with TOU tariffs, the high energy density and ultra-low heat losses mean it can get the best out of all tariff structures. Find which one works the best for you.
Great for the environment: how does TOU tariff help with demand response?
Demand response is adjusting electricity usage in response to incentives or signals from energy suppliers. The goal is to balance the supply & demand of electricity by encouraging homeowners to shift their usage during times when the demand is high or when there are constraints in the energy supply, which would eventually help stabilise grid, manage peak loads and improve grid reliability concerns.
As highlighted by IEA, this is significantly important in the Net Zero Emissions by 2050 scenario as we transition towards the electrification of heat (heat pumps, solar PV & wind) and transport (EVs) and the load on the power grid is likely to intensify.
This is why energy storage technologies coupled with TOU tariff are important in unlocking demand-side flexibility and clean energy transition.
Click here get started: Find stockist and installer – Sunamp UK
Read other articles.
