Background
The £2 million project is the largest single solar energy investment announced to date by the water company’s commercial subsidiary, Scottish Water Horizons. The energy is sold via a private wire power purchase agreement to Scottish Water Group.
The renewable energy generated from the 1MW solar project is expected to provide around a quarter of the annual electricity demand for the site.
The challenges
When RSK Renewables first started to model the scheme, due to DNO restrictions on export we were limited to the size of solar we could deploy. We looked at energy storage solutions to allow us to deploy more solar and still work within the tight export restrictions.
One of the key technical challenges in installing a 0.8MW vanadium flow battery on a commercial site is the complexity of system balancing and managing varying loads throughout the year. Varying seasonal energy demands and fluctuating load profiles require precise control and monitoring to maintain optimal battery performance and efficiency. The battery management system must dynamically adjust to these changes, ensuring that the energy storage and discharge cycles are balanced to prevent overcharging or deep discharging, which could reduce the battery’s lifespan. Additionally, integrating the VFB with the site’s existing energy infrastructure necessitates advanced predictive algorithms and real-time data analysis to anticipate load variations and adjust the system operations accordingly, adding a layer of technical sophistication and complexity to the overall energy management strategy.
The solutions
It was the first Scottish Water solar project to include battery storage, in the form of four vanadium flow batteries (VFBs) supplied by our battery manufacturing partner, capable of storing up to 0.8 MWh.
Vanadium flow batteries explained
Features
- Electrolyte solutions: Utilise vanadium ions dissolved in sulfuric acid.
- Cell stack: Electrochemical reactions occur in a cell stack to enable charging and discharging.
- Flow system: Electrolytes are pumped through the cell stack for energy storage and release.
Benefits
- Long cycle life: Known for their durability and longevity, making them suitable for extensive use.
- Scalability: Can be scaled up easily for large-scale energy storage applications.
- Non-flammable: Uses a liquid electrolyte that is non-flammable, enhancing safety.
- Robustness: More robust and safer compared to lithium-ion systems.
- No degradation: Does not degrade with cycling, ensuring consistent performance over time.
- Long lifetime: Has a lifespan of around 25 years, significantly outlasting comparable lithium-ion solutions.
- Ideal for grid storage: Well-suited for grid storage and renewable energy integration..
The impact
The project will enable around 94% of the renewable power generated to be used on site with the flow batteries charging from electricity produced by solar panels when the sun is at its peak and then delivering it to the site when it is most needed, any time of the day or night.