The UK has witnessed a significant surge in home battery energy storage systems in recent years.
As the country moves towards net zero emissions, the demand for renewable energy solutions has skyrocketed. Homeowners and housing developers alike are actively seeking ways to cut energy bills and carbon and futureproof their homes to comply with legally binding decarbonisation goals.
A key solution gaining traction is pairing renewable energy sources, like solar PV, with battery energy storage systems. Over 1.5 million UK households (approximately 5%) have installed solar panels, marking a significant increase from under a million in 2020. And 43% of UK households with solar panels also have an energy storage battery. Excess energy generated by solar panels during the day is stored for use during peak times.
This excess energy can either be stored in an electric battery or converted into heat and stored in a thermal battery system. Both enable the storage of energy from both solar PV and the grid during off-peak hours, making them a pivotal system of many energy strategies in UK households.
Now that homeowners now have the flexibility to manage their energy usage more efficiently using solar PV, deciding on which complementary energy storage technologies will best meet their household needs is key. Electric batteries can store energy for general household use, while thermal storage systems provide a dedicated solution for heating or hot water. Hot water alone accounts for as much as 18% of total energy consumption in UK homes.
With the rise of time-of-use electricity tariffs, home battery systems are even more appealing – allowing homeowners to purchase cheaper off-peak electricity and use it during peak times, significantly reducing their energy bills.
In the UK, solar PV remains the most popular renewable technology, with over 180,000 certified installations, while electric battery storage systems saw a record 20,000 certified installations. Currently, electric battery storage ranks as the third most popular technology among MCS contractors, with more than 1,100 contractors now certified for battery installations.
As a solar installer, it is essential to explore the various energy storage options available and understand their costs, benefits and potential savings for homeowners.
Both electric storage batteries and thermal energy storage systems have critical roles to play in the evolving landscape of renewable energy solutions.
Electric batteries vs thermal storage: understanding the differences
Electric home batteries, such as the Tesla Powerwall, are often considered the go-to choice for electrical storage. These batteries provide whole-home backup power and manage electrical loads across the household. They store excess electricity generated by solar panels for use when the sun isn’t shining or when electricity prices are high.
It is worth noting, however, that while the electric batteries offer flexibility in powering appliances, lighting and even EV charging, they may not always align with the specific energy needs of homeowners that are primarily focused on optimising their heating or hot water consumption.
In contrast, thermal energy storage, such as Sunamp Thermino heat battery, can provide domestic hot water reliably from the stored thermal energy generated from excess solar PV or off-peak electricity. This makes them an ideal solution for homeowners who want to reduce heating & hot water costs and maximise the self-consumption of solar energy.
Important to note that unlike lithium-ion batteries, Thermino heat batteries store heat, not electricity, making it a more affordable and sustainable choice for managing hot water needs.
With the Future Homes Standard coming into force this year, there is increasing pressure for new homes to be powered by renewables. However, one ever-present challenge remains: how to store hot water efficiently in low-carbon homes?
In renewable-powered properties, especially those with solar PV, grid and heat pumps, energy-efficient thermal storage is no longer a ‘nice-to-have’, it is essential.
For solar installers, this shift presents a valuable opportunity. By adding Thermino thermal battery to your offering, you can provide homeowners with a reliable, cost-effective way to store hot water using free solar or cheaper off-peak electricity – helping them cut bills and increase self-consumption.
Cost efficiency comparison: Sunamp Thermino vs electric home batteries
When comparing energy storage solutions, especially for homes with solar PV, it’s essential to consider key factors like cost per kWh, storage capacity, and lifespan.
Below is a breakdown of how Sunamp Thermino heat batteries compare to electric storage options:
- Purchase price & installation costs of electric batteries
Electric batteries are typically priced based on their storage capacity, with most systems ranging from £2000 to £11000. A brief overview of the typical pricing:
- Electric Batteries (eg lithium-ion):
A 5 kWh battery typically costs around £5000, though the price can vary based on brand and capacity. One of the most popular electric battery brands in the UK costs up to £8000 for 13.5 kWh storage. Installation costs typically go up to £2,000, depending on the system and wiring complexity.
- Sunamp Thermino heat batteries:
In contrast, the Sunamp Thermino heat battery offers a 12 kWh thermal storage capacity for around £3400 (MRRP), whereas the installed price can go up to ~£4300, making it significantly cheaper in upfront costs – and a highly cost-effective solution for homes needing hot water storage, especially those aiming to maximise their solar energy usage or take advantage of off-peak electricity rates.
- Cost per kWh of storage
Cost per kWh is a critical metric for comparing energy storage solutions:
- Electric batteries (lithium-ion):
The cost per kWh for an electric battery system is typically £900–£1,000. These systems power general household electrical loads, including appliances, lighting and EV charging.
- Sunamp Thermino heat batteries:
The cost per kWh of a Sunamp Thermino heat battery is approximately ~£320, making it a much cost-efficient solution for homeowners primarily seeking to optimise their hot water needs.
- Energy storage capacity: Electric batteries vs heat batteries
Energy storage capacity determines how much energy can be stored for later use:
- Electric Batteries:
Electric batteries, such as lithium-ion systems, typically offer capacities ranging from 5 kWh to 15 kWh. A 5 kWh battery is suitable for smaller homes, while larger systems (10-14 kWh) cater to larger households. These batteries can also provide backup power during grid outages.
- Sunamp Thermino heat batteries:
The Sunamp Thermino heat battery offers a 12 kWh thermal storage capacity, enough to provide a family’s hot water needs for an entire day (multiple showers or baths). Smaller units, such as 70L (3 kWh), 150L (3 kWh), and 210L (3 kWh), can be selected depending on the household’s specific hot water requirements. While Thermino heat batteries are not designed for whole-home electrical use, they are highly efficient in reducing grid electricity consumption for hot water production, especially when paired with solar PV systems. Take the case of EastHeat trial – the largest residential heat storage project in Europe at the time – where up to 63% of hot water energy consumption came from solar PV generated electricity, dramatically cutting bills for residents and helping combat fuel poverty.
- Lifespan & warranty
The lifespan of energy storage systems is crucial for long-term value:
- Electric Batteries (lithium-ion):
Lithium-ion systems typically last between 10 and 15 years, with warranties generally covering 10 years. These batteries have a limited cycle life (3,000 to 5,000 cycles), which means homeowners may need to replace them once or twice during the average 25-year lifespan of a solar panel.
- Sunamp Thermino heat batteries:
Sunamp’s Thermino heat batteries feature a lifespan of 50+ years, thanks to the patented phase-change material (PCM) technology, which provides over 40,000 charge/discharge cycles. The Plentigrade PCM used in Thermino batteries is lab-tested, and does not degrade like lithium-ion batteries, offering decades of reliable domestic water heating without the need for replacement.
- Savings
Electric Batteries:
Electric storage systems, such as the Tesla Powerwall, reduce electricity bills by storing excess solar energy during the day and using it during peak times. One analysis estimated about £280/year savings from using stored off-peak electric power during peak hours. According to another study, a medium-sized home with solar panels and a battery size of 8kWh could save up to £600/year on energy bills.
Sunamp Thermino heat batteries:
A Thermino heat battery can also deliver significant savings by allowing homeowners to cut grid electricity or gas for hot water. For instance, in this case, Thermino heat batteries have been able to save homeowners £485 per year on water heating costs (based on the previous ‘per kWh electricity’ prices). With a lifespan of 50+ years, homeowners can enjoy long-term savings without the need for frequent replacement.
Before we explore the broader strategic picture, it’s worth underscoring four key benefits of PCM‑based thermal storage, the core technology behind Sunamp Thermino heat batteries:
- Space‑efficient energy density
By storing energy as latent heat during a material’s phase change, PCMs deliver greater energy per unit volume than conventional chemical batteries. This makes PCM stores especially compact solutions for hot water storage without compromising capacity. - Minimal standby losses
Once charged, a PCM thermal store held at its phase‑change temperature will retain its heat for extended periods with only negligible losses – provided the unit is well insulated. Electric batteries, in contrast, can lose several percent of their charge each month to self‑discharge. - Passive thermal regulation
During melting and solidification, PCMs maintain a constant temperature through latent heat transfer, eliminating the need for energy‑hungry cooling or heating systems. Electric batteries often require active thermal management to avoid overheating in summer or capacity loss in winter. - Lower environmental footprint
PCM thermal stores are manufactured from non‑toxic, recyclable materials without heavy metals or hazardous chemicals. Lithium‑ion batteries, by comparison, rely on metals such as lithium, cobalt, and nickel, which demand careful end‑of‑life recycling.
Conclusion: A strategic solution for solar installers and homeowners
All things considered, Sunamp’s Thermino heat battery provides a cost-effective, long-term solution for homeowners looking to manage hot water efficiently while reducing energy costs. Compared to electric batteries, Thermino heat batteries offer a lower cost per kWh, a significantly longer lifespan, and a lower price point & environmental footprint, which means lower up front cost – making it the ideal choice for households needing hot water storage with widescale renewables adoption.
For solar installers, with the growing demand for holistic energy strategies that address both electricity and hot water needs, integrating thermal storage into your services allows you to cater to a broader range of customer requirements. Thermino heat batteries offer excellent long-term value with minimal maintenance and installation complexity, helping you differentiate your services and expand your business.
Next steps: expand your offering by integrating thermal energy storage for domestic hot water, enabling your customers to get even more from their solar PV systems.
Reach out to us today for more information and expert guidance. Click here to get in touch.
We also offer a FREE installation training. Sign up today.
