What are the key considerations for building new, or transitioning existing, HGV depots to fully electric multi-megawatt facilities? Andy Vickers, Business Development Manager at energy company Vattenfall, gives a deep dive on the 10-step design and planning process.
1. Matching connection size to charging demand
One of the first, and most important, considerations is a company's ‘ultimate load scenario', which refers to the development endgame. It can be a very costly, disruptive and time-consuming process to go back and upgrade an electrical network once the backbone infrastructure has been installed, so it is important to plan ahead and design networks for the ultimate electrical charging loads which are likely in the future.
2. Establishing site loads
Site electrical loads are determined by the quantity of HGV's a facility needs to charge at any given time, the size of the batteries of the vehicles, and the charging times that need to be achieved. A detailed load and time of use profile must be established to fully understand the power requirements under every use scenario. A facility that has ample time to charge HGVs overnight, for example, would need a much less power to one where trucks pull in for pit stops on long distance journeys and need to charge at speed.
Power failures can be catastrophic for business-critical charging facilities where downtime leads to loss of revenue, loss of reputation and loss of customers. It is imperative to design networks with redundance and resilience at their core. Power networks should incorporate N+1 designs and HV ring circuits to ensure single point failures don't take down the whole site. For critical applications, dual connections to the grid at different substations may be required to ensure a secure energy supply from the grid.
Good quality modern substation equipment is highly unlikely to fail, but if it does, it's best to be prepared. It's good practice to allow for the connection of an emergency backup power source onto the main low voltage (400V) switchboards; traditionally this would be supplied via a diesel generator, but in today's Net Zero world this should be through connection of battery storage systems, ideally charged by renewable power from solar or wind.
The Electricity at Work Regulations mandates "the need to carry out suitable and sufficient assessment of risk, and to put measures in place to protect those who could be put at risk". This indirectly infers that Arc Flash studies are mandatory, and that equipment designed and tested to reduce the impact of and arc flash to personnel and property should be incorporated within network designs.
Charger suitability will depend on the vehicles, their charging requirements, and their connector types. High-power charging for vehicles such as HGVs, require DC power, however AC is a viable (and cheaper) option for vehicles that can be charged overnight. DC chargers are available in a traditional stand-alone design, or more recently as multi-megawatt power centres, which are particularly suited for dense parking applications such as depots. Most electric vehicles are now compatible with the latest CCS2 connectors, however some vehicles still use less popular CHAdeMO designs. Also bear in mind the new Megawatt Charging standard (MCS) products will soon be with us. Checking charger compatibilities ahead of time is therefore essential.
When evaluating equipment be cautious with chargers costing 50% or less than the main tier one OEM's products, they are not equal in many respects. eHGV charging facilities demand the highest quality and reliability, therefore only high-end chargers should be considered.
6. Watch out for harmonics
High harmonics, and poor power quality, can wreak havoc on any site, resulting in premature failures of critical equipment. High power eHGV charging facilities exacerbate this problem because they are nonlinear loads. Distribution Network Operators (DNOs) who are responsible for delivering power from the grid, can disconnect a business's power if a facility is found to be non-compliant with the power quality standard G5/5. Chargers that do not utilise IGBT PWM technology are unlikely to comply with the G/5 standard when used on high power eHGV charging facilities.
7. Time is of the essence
There is a limited (and rapidly diminishing) amount of capacity available via the UK power grid. Heightened demand for new grid connections from already constrained networks is leading to long delays, where in some cases customers are being quoted 10+ years for new grid connections. UK Electricity demand is predicted to double in the next 30-years as we move towards Net Zero, therefore pressure on UK grids is only going to get worse, hence we recommend early engagement with your DNO or IDNO (Independent Distribution Network Operator) to secure the power you need for your project.
Owning and operating a high-power electric HGV charging facility comes with onerous and complex Duty Holder liabilities at law with respect to health and safety, environmental & technical regulations. Serious breaches are subject to prosecution, unlimited fines and potential jail time. Compliance with these mandatory regulations requires deep knowledge and competence within a business and will likely require investment in new highly skilled personnel for the transport sector.
9. Seek specialist support
Designing, and operating high-power electric HGV charging facilities requires specialist electrical knowledge, which is not typically the purview of traditional fleet businesses or run-of-the-mill building services consultants or contractors. A detailed knowledge of power electronics is required, as is securing a timely grid connection at the optimum capacity required for HGV charging. Businesses wanting to avoid delays and inflated costs in securing a grid connection can partner with an IDNO, who offer an alternative route onto the grid, they can reserve capacity on their clients' behalf, and provide ‘Asset Adoption payments', a cash injection to reduce the capital cost of designing and building new power networks for developers.
10. Plan for investment competence
The investment required for the infrastructure and equipment for a high-power electric HGV charging facility can be significant. Operational Leasing such as Power-as-a-Service from Vattenfall can provide an attractive option for owners looking to outsource the design and construction together with all operational risks and responsibilities to a specialist, who can also provide the investment capital for the electrical infrastructure and provide operational expertise throughout the facilities life.