UK Residential 40kWh Energy Storage System Case Study: Wall-Mounted Batteries Combined with Sunsynk Inverters

The UK energy market has undergone significant changes in recent years, with high residential electricity costs driving rapid adoption of home solar PV and energy storage systems. This case study details a 40kWh Power Wall Storage Battery installed by GSL ENERGY in a UK home in September 2025, achieving maximized energy utilization through optimized design.

For this residential project, the homeowner selected four GSL ENERGY 10kWh lithium batteries, installed in parallel, to achieve a total capacity of 40kWh. The wall-mounted batteries feature a compact design that saves indoor space while enhancing overall aesthetics.

The system incorporates two Sunsynk 8.5kW hybrid inverters, enabling simultaneous management of PV generation and battery storage to ensure efficient power conversion and load distribution.

Total Energy Storage Capacity: 40kWh

Inverters: Sunsynk 8.5kW × 2

Installation Method: Wall-mounted array for easy maintenance

Applications: Daily electricity optimization, time-of-use tariff savings, backup power during outages

UK Energy Storage Market Context

Photovoltaics and Energy Storage Integration Intensifies

Over one million UK households now have solar installations, driving corresponding growth in battery storage installations.

Energy Prices Drive Investment

Significant electricity price hikes in recent years have prompted many households to use battery systems for charging during off-peak hours and discharging during peak periods, thereby reducing overall bills.

Market Mechanism Changes

Despite the absence of national subsidies, some energy companies have introduced electricity purchase/sale plans integrated with batteries, such as Octopus Energy's “Smart Battery Plan.”

Product Trends

Modular batteries are gaining popularity, with 10kWh units as the base module. Users can scale up to 40kWh or larger as needed.

Industry Development Observations

Home Systems Shift Toward Higher Capacity

UK households are upgrading from common 5-10kWh storage to 20-40kWh systems, meeting increased energy demands.

Higher Inverter-Battery Compatibility

Brands like Sunsynk continuously optimize battery compatibility, enhancing installation ease and operational stability.

More Predictable Economic Returns

Under time-of-use pricing, energy storage batteries help users achieve payback within 7-10 years.

Market Scale Continues to Expand

Projections indicate the UK's total installed energy storage capacity could exceed 20GWh by 2030, with residential storage holding a significant share.

Case Value

This 40kWh project demonstrates that the combination of GSL ENERGY's 10kWh modular battery and Sunsynk hybrid inverters not only meets daily household electricity needs but also delivers stable economic benefits and energy independence for users.

As energy storage penetration grows in the UK market, such projects will become the standard model for future home energy systems.