Rotherham General Hospital



Public Sector


Energy Efficiency

Reducing Energy Costs

Power Resilience


Battery Energy Storage

Uninterruptible Power Supply (UPS)

Rotherham General Hospital is an acute general hospital in Rotherham, England.


Powerstar were engaged to supplement Rotherham General Hospital’s power resilience strategy with an efficient, intelligent Battery Energy Storage System (BESS) with Uninterruptible Power Supply (UPS) functionality. As UPS systems are used to ensure critical care systems remain online in the case of a power disruption, it is vital that any proposed installations are tested to the most rigorous standards and will operate exactly as intended.

Traditional UPS suffers from significant losses, typically around 10% of their total capacity. For a typical hospital installation, this equates to around £262,000 in additional energy costs annually, as well as adding around 210 tonnes of CO2e to their carbon footprint. Traditional UPS is also inflexible and unable to carry out other tasks, and there is no accurate way to determine the state of charge of a battery. This risks them failing in the event of a significant power disruption.


Powerstar proposed to provide UPS with a BESS that also incorporated the rapid switching speed and reliability of a UPS. As well as providing the same instantaneous load support as a UPS, but with the ability to support an area and not just specific systems, BESS offers much lower losses at less than 1% of total capacity. In addition to this, a BESS can be used to engage with Grid Services and Demand Side Response to generate additional revenue and further reduce electricity costs, as well as being used to store renewable electricity generated on-site, such as that from rooftop solar, to further improve sustainability performance.

Powerstar’s BESS is protected by warranty for 15 years and has a typical system lifespan of around 25 years. This contrasts with traditional UPS, where batteries need replacing between every 7 and 10 years. Batteries are cycled daily, ensuring that they are functioning correctly and can meet NHS minimum requirements of 20 minutes load support in the event of power disruption. The BESS solution from Powerstar is the first HTM-06-01 compliant commercial BESS system with UPS capabilities and the ability to access Grid Services.


BESS offers savings through greater energy efficiency of around £225,000 annually, as well as eliminating around 190 tonnes of CO2e. Grid Services can also generate around £100,000 in additional revenue on top of that saving.
Annual savings of
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and eliminated 190 tonnes of C02e


For Rotherham General Hospital, the 500kW/500kWh Powerstar system was called upon two times in the same day in April 2022 to protect critical care at the hospital from power disruption.

The grid failed twice, and each time the BESS seamlessly supported the full load, first for a period of 15 seconds, and the second for a period of 23 seconds. The graph shows one of these UPS events.

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