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Dundee City Council: Princes Street charging hub

Connected Energy worked with SWARCO and Dundee City Council in 2018 to provide battery energy storage to one of the most advanced EV charging hubs of its time. The system is being used to support the changing energy profiles of this busy site, working alongside a solar PV array to support peak shaving and periods of high demand.

  • Industry:  Local Authority
  • System no:  1
  • Power:  60kW
  • Capacity:  90kWh
  • Application:  EV charging
  • Functionality:  PV, grid-load management, cost reduction and fleet decarbonisation


Dundee City Council is a pioneer in electric vehicle adoption and charging provision. As part of a wider infrastructure roll-out programme, supported by Dundee’s Go Ultra Low Cities scheme, they developed the Princes Street charging hub.

What was once a petrol station, the site was developed to include two double 22kW and seven 50kW chargers, alongside a PV charging canopy and battery energy storage, supplied by Connected Energy.

The site was open to the public and has become heavily used by the City’s taxi fleet. In the first year alone, the hub delivered 24,000 charging sessions.

The Brief

Dundee City Council were looking for innovative solutions to allow them to maximise the PV solar canopy on site and ensure that they were charging vehicles with greener, cleaner energy for longer. They were therefore looking for an energy storage solution that would capture on-site generation and manage the energy flow to the assets at the hub.

Not only was their motivation to support the City’s decarbonisation agenda but it would also help to reduce the site’s overall operating costs by allowing renewable energy to be stored and used. This would help the Council to reduce their demand from the national grid at peak times and be in the position to take advantage of off-peak charging tariffs.

In addition, they also wanted to trial peak shaving, to minimise demand on capacity when multiple customers were charging. They required a solution that could also allow the site to be future-proofed to allow for more powerful chargers in the longer term.

The Solution

Connected Energy installed our E-STOR system alongside the EV chargers and PV canopies managed by our back office control system. The system is programmed to set the battery to charge and discharge according to when predetermined criteria are met; charging when the sun is shining, and discharging to manage capacity when the power demand from the chargers is high.

The system used by Dundee City Council tracks usage of the chargers and the generation of the PV and works to maximise the amount of renewable energy that is used to charge the vehicles. The E-STOR system will achieve this by managing its state of charge to store as much PV generated electricity as possible.

It also tracks the EV chargers so that as they are used, the E-STOR discharges to provide the energy to them via OCPP. When the system is overcharged or requires additional charge it will take advantage of amber and green tariff periods to minimise the operating cost.

The solution also circumvents a major issue many organisations face when looking to install EV charging sites – which is current grid capacity to site. If a site is looking to install five 50KWh charging points, but only has grid access to service 40KWh chargers, it would have originally required a rethink of the entire project, or a substantial grid upgrade. With onsite battery storage, you can avoid this, whilst maximising generated renewable energy.

The E-STOR system makes upgrading the energy capacity of the site easy to achieve. The systems are modular and scalable in design, offering a range of configurations suitable for the varied requirements of industrial and commercial customers. This will allow Dundee City Council to add more chargers to cope with growing demand.

Next Steps

With the concept proven, Connected Energy is working with both SWARCO and Dundee City Council to include additional battery energy storage systems for two more hubs – both for public and the council’s own fleet depot.

Dundee battery energy storage for EV charging

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