How to Achieve Sustainable Power Without Changing Your Existing Backup System
A manufacturing site in southern Germany has shown how battery storage can reduce diesel use and raise solar consumption without replacing emergency backup infrastructure. The facility added a 700kW battery system and control software to coordinate its existing solar array, diesel generator, and grid connection. The result is higher renewable use, lower fuel costs, and reliable power during outages.
For UK manufacturers, the approach offers a practical template. Many industrial sites installed solar panels years ago but still run diesel generators for backup power. Adding battery storage between those systems can increase the value of both assets while cutting carbon emissions and operating costs.
The challenge for most factories is economic. Replacing a working backup generator is expensive, particularly when production cannot tolerate power interruptions. However, retrofitting storage and control systems around existing equipment costs less and delivers measurable savings faster. This balance matters in sectors where margins are tight and capital budgets are under pressure.
Moreover, the combination addresses several commercial realities at once. It reduces diesel consumption, lowers maintenance frequency, improves power quality, and raises the proportion of energy generated on site. Consequently, the payback calculation becomes easier to justify, especially where fuel prices remain volatile or grid tariffs include demand charges.
Battery system bridges solar generation and backup diesel
The Schwabmünchen site installed seven liquid-cooled battery units with a combined capacity of 1,624kWh and an output rating of 700kW. Those units now work alongside a 440kWp solar installation and a 500kW diesel generator that was already in place. An energy management system decides when to charge the batteries, when to draw from solar, when to use stored energy, and when to start the generator.
Previously, surplus solar electricity either went unused or exported to the grid at low prices. Meanwhile, the diesel generator ran inefficiently during partial-load conditions, consuming more fuel per kilowatt-hour than necessary. The battery system smooths out both problems by storing excess solar power during the day and releasing it when demand rises or when sunlight fades.
Importantly, the diesel generator remains available for extended outages or high-demand periods that exceed battery capacity. The difference is that it runs far less often and operates closer to its optimal efficiency range when it does. As a result, fuel costs fall and maintenance intervals lengthen.
The control software is central to the design. It monitors real-time energy flows, forecasts solar generation based on weather data, and manages charging schedules to ensure the battery is ready when needed. During grid outages, the system switches automatically to island mode, using solar and battery power first before starting the generator. This sequencing reduces diesel runtime and associated emissions.
Industrial energy costs and carbon pressure collide
UK manufacturers face rising electricity costs, tighter emissions reporting, and increasing scrutiny from customers and supply chains. Many businesses have already installed solar panels to offset daytime energy use. However, solar alone cannot guarantee continuity during outages, nor can it cover evening or early-morning shifts when production often continues.
Battery storage changes that equation. It allows factories to shift solar generation across time, using it when it delivers the most value rather than when the sun happens to shine. This capability is particularly valuable for sites with time-of-use tariffs, where peak-period electricity costs significantly more than off-peak supply.
Furthermore, energy resilience has become a boardroom issue. Supply chain disruptions, extreme weather, and grid instability have made backup power a business continuity priority. Diesel generators provide reliability, but they carry reputational and regulatory risks as decarbonisation expectations tighten. Battery storage offers a way to reduce fossil-fuel dependence without sacrificing resilience.
For SMEs considering similar upgrades, the financial case often hinges on three factors: current diesel consumption, the gap between solar generation and on-site demand, and the cost structure of grid electricity. Sites with high diesel use, significant solar export, or expensive peak tariffs typically see the fastest payback. Additionally, grant funding and capital allowances can improve project economics, though availability varies by region and sector.
There is also a compliance dimension. Large companies increasingly require suppliers to report Scope 1 and Scope 2 emissions, and some set carbon-reduction targets as tender conditions. Battery storage reduces Scope 1 emissions by cutting diesel use and can lower Scope 2 emissions by reducing reliance on grid power during high-carbon periods. These improvements can help SMEs meet customer requirements and protect existing contracts.
Key details from the Schwabmünchen installation
- The site added 700kW of battery power and 1,624kWh of storage capacity to an existing solar and diesel system.
- Seven liquid-cooled battery units were installed, each rated at 100kW output and 232kWh capacity.
- An energy management system coordinates power flows between solar, battery, grid, and diesel generation.
- The diesel generator remains operational for backup but runs less frequently and more efficiently.
- The project was designed as a retrofit, avoiding the cost and disruption of replacing existing infrastructure.
- The facility is located in Schwabmünchen, Germany, and the installation was completed in 2026.
What UK manufacturers should consider before retrofitting storage
Battery storage is not a universal solution, and the business case depends on specific site characteristics. Manufacturers should start by analysing current energy use, diesel consumption, and solar generation patterns. This data reveals whether storage can shift enough energy to justify the capital cost.
Next, consider the existing electrical infrastructure. Some sites may need upgrades to accommodate battery inverters, control systems, or additional switchgear. These costs must be included in the financial model. However, in many cases, existing equipment can be adapted without major redesign, as the German example demonstrates.
Operational continuity is another critical factor. If production cannot tolerate even brief interruptions, the control system must be configured to switch between power sources seamlessly. Similarly, if the site has highly variable demand, the battery must be large enough to cover peaks or the generator must remain available as a secondary source.
Maintenance requirements also matter. Battery systems typically need less intervention than diesel generators, but they do require monitoring, software updates, and eventual replacement after 10 to 15 years depending on usage patterns. Consequently, total cost of ownership should include these lifecycle expenses, not just upfront capital.
Finally, think about future requirements. If the site plans to expand production, add electric vehicle charging, or install additional solar capacity, the storage system should be sized accordingly. Modular battery designs can be expanded over time, but planning for growth from the outset avoids costly retrofits later.
For businesses already working toward carbon reporting compliance under PPN 06/21 or similar frameworks, battery storage directly reduces Scope 1 emissions and can support net-zero commitments. It also provides measurable data for annual carbon reports, making progress easier to demonstrate to customers and regulators.
Control systems determine whether storage delivers value
Hardware alone does not guarantee savings. The energy management system must be configured to match the site's operational patterns, tariff structure, and resilience requirements. Without intelligent control, batteries may charge and discharge at suboptimal times, reducing financial returns and potentially increasing costs.
Good control systems monitor multiple variables simultaneously: real-time demand, solar output, battery state of charge, grid tariffs, and weather forecasts. They use this information to decide when to store energy, when to use it, and when to draw from the grid or start the generator. These decisions happen automatically, hundreds of times per day, based on rules set during commissioning.
Businesses should also consider integration with existing systems. Many factories already use building management systems, SCADA platforms, or energy monitoring tools. Battery control software should communicate with these systems to provide a unified view of energy use and allow centralised management. Proprietary systems that operate in isolation often create data silos and limit operational flexibility.
Furthermore, software updates and algorithm improvements can enhance performance over time. The best systems learn from historical data and adjust their behaviour to changing conditions. This adaptability extends the useful life of the hardware and ensures that the investment continues delivering value as energy markets and regulations evolve.
Training is equally important. Site staff need to understand how the system works, how to interpret performance data, and when to intervene. Training programs on energy management can help teams get the most from storage investments and identify opportunities for further efficiency gains.
Regulatory and funding landscape in the UK
Several UK funding schemes support industrial energy efficiency and decarbonisation projects. The Industrial Energy Transformation Fund, managed by the Department for Energy Security and Net Zero, provides grants for energy efficiency measures, including battery storage in certain circumstances. Eligibility depends on sector, project size, and expected carbon savings.
Additionally, the Enhanced Capital Allowance scheme allows businesses to claim 100 per cent first-year relief on qualifying energy-saving equipment. Battery storage systems may qualify if they meet specific criteria, though businesses should consult with tax advisers to confirm eligibility based on their individual circumstances.
On the regulatory side, the Streamlined Energy and Carbon Reporting framework requires many companies to disclose energy use and emissions annually. Battery storage can reduce reported emissions by cutting diesel consumption and shifting grid use to lower-carbon periods. This improvement supports compliance and demonstrates progress to stakeholders.
For businesses tendering for public sector contracts, PPN 06/21 now requires suppliers to publish carbon reduction plans and demonstrate progress toward net zero. Retrofitting battery storage provides tangible evidence of decarbonisation efforts and can strengthen tender submissions. Our compliance support services help SMEs navigate these requirements and align energy investments with procurement criteria.
Meanwhile, grid operators are increasingly interested in demand flexibility and distributed energy resources. Some battery systems can participate in frequency response or demand-side response schemes, generating additional revenue by providing grid services. However, participation typically requires larger installations and specific technical capabilities, so it may not suit every site.