Bi Directional EV Charge point

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by Stephen Cornthwaite

At this time within Australia ,as far as I am aware there is no available “off the shelf” EV systems which allow for the use of the mobile storage platform (Electric Vehicle Battery) to supply external loads (ie to power the home or business).

There is however some international development within this area and it looks like the precursor for the development of both the technology application and the business model necessary to support the concept is Mitsubishi with its “Dendo Drive House” concept.

The product will not be available for use until late 2019 in Japan and Europe, its likely that Australia will not see the Dendo made available for several years.
The Mitsubishi concept is to be offered as a bundle to purchasers of a new EV/ PHEVs with Sales, Installation and after sales maintenance included. The system including the bi directional charger, Solar Panels and an additional home battery would have to be installed by an approved Mitsubishi installer.

At this time and for the foreseeable short term the bi directional concept is only available as a bespoke engineered response, not a manufactured roll out.

Part of the difficulty with applying the concept in the real world involves the process by which the manufacturer can be able to offer any guarantees regarding the reliability and safety of their product when connected / used by an uncontrolled external environment. Mitsubishi’s Dendo Drive Home uses a vertically integrated whole beast model. Ie, Mitsubishi own and control the supply, installation and on going maintenance for the whole package. The same model would need to apply with any bespoke solution.

I have been discussing the feasibility for utilizing a small EV bus or commuter conversion package for trialling a bi direction charge station with EVs Canberra. The initial conversion package we have been looking at comprises a 30kWhr battery giving a 10/12 seat bus a range of between 150 & 300km. It is anticipated that a full charge would take around 1- 1.5 hrs via a 22kW charge station and that the EV bus could be scheduled to only require a 1/4 to 1/2 capacity charge for most daily duty requirements, ie as a trail adjunct to a community fleet or for an application for Yumaro.

I need to stress here that this is not the Yellow Bus /EV community bus proposal, there are several key differences the the basic business model for the Yellow Bus proposal; Which I am more than willing to provide detail on and re iterate that detail ad infinitum to peer test until the detractors actually realise what a workable and easily realisable proposal it is.

Back to the Bi directional charge station; the effective management of the EV journey schedule could easily realise a 15kW + storage ballast for use by the premises loads essentially working as a capacitive ballast to increase the efficiency of any installed PV generator. (Vastly improving the self consumption of generated solar inputs). Especially relevant where any other export control issues may compromise life cycle costing benefits for an installed PV system.
It would also be available for use by essential circuits to provide basic facility in the event of a grid power fail.

In the first instance I would be proposing the application of an inverter /charger package based around the Australian made Selectonics SP pro series or Victron equipment. Both manufacturers offer reliable high quality bi directional stackable and adaptable storage management options. The challenge will be making the bi directional nature of the charge point interface simple, robust and self managing. Ie being able to plug it in and walk away without requiring any understanding of the device other than, you must unplug it before you can drive away.
We(MESA) are already well versed with this kind of approach, having had to apply it for most of our on grid and off grid residential and commercial customers over the years.

Further involvement could be encouraged from a Queensland based EV manufacturer and research engineers at the University of Queensland.

A bi directional charging facility is definitely workable and provided funding can be made available its development and application would serve to kickstart a small local industry at a time when the perfect wave of opportunity is right behind us.
We have the knowledge, expert ease and practical capability locally, to realise the concept.
It should probably be declared at the outset and made evident beyond common sense that provided any project is managed without political interference during the proving stages, there would be no risk associated with supporting such a venture – and the obverse is of course also true.