This project will be supported and delivered in conjunction with the Scottish EV Strategic Working Group and will develop a standard and specification of temporary and portable EV charging infrastructure devices to provide provisional capacity to meet short term demand in a location.
Objectives
1 Identify detailed use cases for these mobile charge points which will include cases where there is a need to coordinate their connection and operation with constrained networks.
2 Develop a standard and specification for portable temporary EV chargers with key external stakeholders to assist with network resilience and meet short term demand.
3 Procure and demonstrate an agreed specification for portable EV charger.
4 Identify the challenges of providing short term access to the network for temporary EV charging, including any regulatory changes that would be required to facilitate it.
5 Develop a commercial ownership model including a cost benefits analysis to understand the viability of wider roll out and adoption.
Learnings
Outcomes
The project has investigated the associated use cases for a mobile charging unit and the outline requirements of a portable charging solution. The project was prematurely closed due the limited benefits which are immediately available as EV uptake is still low and it may be something which is needed to be investigated further in the future. The learnings around temporary charging are still being investigated through the Resilience as a Service (RaaS) project and E tourism as well as WPD’s NIA_WPD_056 Temporary Event Charging project.
Lessons Learnt
The learning captured during this project are outlined below:
Metering
Any temporary EV Charging unit which is non-operational could be ‘trickle charged’ (the batteries topped up) via a permanent metered connection at the operator’s site, for example a local authority depot. All energy used at that site could be appropriately metered and paid for via the operator’s normal billing arrangements with its supplier of choice.
However, when the unit arrives at a pre-prepared site, it requires a connection to a supply point, referred to earlier, otherwise its storage capacity will be quickly depleted. Conventionally each of these supply points would have an individual MPAN meter with an associated standing charge. With a number of these connection points likely to have infrequent usage, an alternative arrangement was investigated to reduce the associated standing costs.
The unmetered supply regulations allow a supply greater than 500W to be unmetered where the load is predictable in nature and it is impractical to provide a metered supply for the following reasons:
•Any metering costs are expected to be significantly higher than the usual charges for a similar metered connection.
•Where there are technical and practical difficulties in providing a metered connection. For example, the location of the supply point would require the metering to be installed next to a busy road or the size of the metering equipment prevents it from being installed in an appropriate weathertight metering box.
•Any legal and safety considerations involved in the installation and reading of a meter.
Note that the UK Government Department for Business, Energy & Industrial Strategy (BEIS) advises supplies to electric vehicle charging points should generally be metered because of the size of the load and the inability to predict the usage of such points. As a result, a key learning point is that temporary EV chargers connected to the network must be metered.
Measured Centralised Management System (MCMS)
The concept of unmetered connections is well known, and it is used extensively for stair lighting and access systems in common stairwells together with street lighting columns. However, in these applications the energy use is small and fixed enabling the supplier to establish a fixed monthly bill.
In this novel application, where the energy consumption by a temporary EV charger on-site will be considerably larger, a refinement to the above system is required. With the advent of newer technologies, particularly street level EV charging, a newer metering technology has begun to evolve. The asset, in this case the mobile charging unit, is assigned a Central Management System ID, which records the power consumed via actual on/off switching times and is stored on board. These power event logs are transmitted to the Meter Administrator, who can then use the inventory to calculate the Half Hourly data. This in turn is then sent to the owner/operator’s energy supplier for billing purposes. The owner of the temporary EV charger may be a local authority or a private operator.
There is one potential drawback to this methodology which requires further investigation. It appears the MCMS calculates charges based on the notional power of the unit and the connection time. While this is acceptable if the connected device draws a consistent load throughout the connection time, it is more likely that the energy consumed will vary as the batteries regain full charge and therefore it is possible the calculated energy consumption will be higher than the actual figure. One way to address this problem is for the temporary EV charging unit to have an on-board meter to allow a comparison to be made. But whether or not, this can be factored into a MCMS generated bill remains to be understood.
