Do I need one?

A major constraint to consider when deploying multiple EVs in any depot is how much spare electrical capacity you have and when it is available. Spare capacity means the peak power available on-site minus all existing loads that need to be supplied prior to any charging infrastructure installation. Charging multiple EVs, even on lower powered chargepoints can quickly use up the power you have available on site. Early in any charging infrastructure project you should assess how much capacity you have available, when it is available, and you should also get in touch with your Distribution Network Operator (DNO) to find out early on if you are able to increase your capacity. They will also be able to give you a cost estimate for the work. However, please note that each site is different and may have different grid upgrade requirements or different DNOs.

Some sites will not be able to support chargers with more than a certain power without a grid upgrade. This is especially important in the case of electric trucks, which may require high charging powers if they need to be topped up during, for example, a lunch break or a change of shift. This is also known as ‘opportunity charging’. However, once the current and future demand of EVs charging on the site has been understood, if the unmanaged demand is greater than the supply, solutions to reduce the demand should be considered before going down the grid upgrade road straightaway.

One of these solutions can be load management, which is the process of controlling when charging happens and the power delivered by the chargepoints to avoid exceeding local power constraints. Load management can reduce spikes in power demand by smoothing the charging over time, which can reduce the peak power required by the site. Depending on the level of load management (how intelligent the system is) the price can vary.

For an introduction to load management and the effect it will have on site energy demand please refer to these Cenex documents: Introduction to Load Management and Site Assessment Methodology. These documents also brief you on another option to avoid/defer a grid upgrade: on-site storage and generation. An energy storage system, typically a battery energy storage system (BESS) located on-site, is charged when demand is low and/or supply is high and then discharged when demand is high and/or supply is low. On-site generation can provide you with further independence from the grid via small-scale wind or solar photovoltaics (PV), connected as part of the site’s energy system behind the meter.

If you need a grid upgrade…

After assessing the power demand, if there is still greater demand than supply, an electricity connection upgrade will likely be required. This upgrade will need to be completed by your DNO and therefore, you will need to get in touch with them about your upgrade request. The DNO will then quote you for the works, which are split into contestable and non-contestable. The non-contestable works must be completed by the DNO, however, the contestable works can be completed by a third party. Examples of non-contestable works are site evaluation and network access enablement. Examples of contestable works are ground works. Costs and timescales can vary depending on the DNO and kVA rating power of the required connection. For more detail on costs and timelines see the Site Assessment Methodology document from Cenex.

For any EV charging project, it is recommended that the relevant DNO is engaged as soon as possible. There can be substantial lead times on DNO upgrades, depending on the size of the upgrade, therefore it is important to begin this process early in the planning stages of the charging infrastructure installations. The site in the BETT project that is in the process of a power upgrade is being supported in the interim through the deployment of mobile chargers. These are a potential contingency where significant delays are experienced in the initiation and completion of the DNO works. 

Upcoming changes in costs

It is important to note an upcoming change in the scope of costs regarding grid upgrades: the Access and Forward Looking charges Significant Code Review starting in April 2023. The overall connection charge will be reduced, and the charge for wider distribution network reinforcement (above the voltage level of connection) is removed, with limited exceptions. Going forwards, if a site needs a connection, they will have to pay for any 'sole use' assets (i.e. equipment that no one else on the network will use), but any upgrades required further up the network will be removed (with limited exceptions) and recovered via Distribution Use of System (DUoS) charges. There is an upper limit to this, which is meant to dissuade the most expensive applications, whereby any upgrade costs in excess of £1,720/kVA would have to be paid for by the applicant. All this means that a depot would still be charged to upgrade its supply for all the sole use assets, but they would be insulated from potentially crippling costs incurred by reinforcements to the wider network (e.g. transformers and lines down the street). These changes will apply only to applications received from 1^st April 2023. More information can be found here.