Many Australians are having an epiphany: electric vehicles are big batteries on wheels that could, in theory, be used to power our homes using a V2H (Vehicle to Home) system.
However, only one full EV currently does this: the ageing Nissan Leaf Gen 2. Moreover, only one home EV charger is compatible with the Nissan Leaf’s V2H system – the Wallbox Quasar. And that’s been discontinued.
So, V2H in Australia is seemingly impossible right now. Or is it?
An increasing number of EVs1 let you power a load through the car’s charging port (V2L) as demonstrated by this MG owner2 :
What if we could buy a device that converted V2L cars to V2H?
The HOEM (Home Open Energy Manager) is a device that promises to do just this, but what exactly does it do, and is it legal to use? Read on to find out. But first, let’s make sure we understand the bidirectional jargon.
Know Your Acronyms
V2G = Vehicle to Grid
V2G is bi-directional charging, where you can charge your car quickly; and discharge energy to support major loads in your house.
Previously, if you had a Nissan Leaf and lived in South Australia, the Wallbox Quasar was an approved solution. However, it was not a grid-forming inverter, so it didn’t work during a grid outage, which was a hard pill to swallow for something that cost $10,000+
V2L = Vehicle to Load
V2L offers a flexible supply from your car to almost anything.
From a modest few hundred watts—ideal for charging gadgets—to heftier outputs like 2kW or 3.6kW (8 to 15 amps), it can be as gutsy as a standard power point to run small appliances or even a kettle, provided there are no large surge loads.
Imagine V2L as a camping generator. It’s legal to use in the same fashion, but quieter and without the lethal fumes.
V2H = Vehicle to Home
There’s a crossover between V2G and V2H, which arguably hinges on the inverter’s location—either mounted on your house wall or integrated into your vehicle.
For this discussion, we’ll define V2H as the wiring that allows you to power your house using the V2L inverter in your car.
The setup is the same as running a little Rhonda generator to power a caravan: you’ll have a 15amp inlet socket with some essential circuits devoted to it.
It won’t be capable of running larger loads like ducted aircon or a rainwater pressure pump. For that, you’d need a diesel generator the size of your dining table (and perhaps a 32-amp socket)
Why V2L Can’t Directly Power Your Home
You can’t plug a V2L car directly into an Australian switchboard if there’s an earth leakage safety feature in the EV’s V2L output. The car’s safety mechanism interprets the home’s Multiple Earth Neutral (MEN link) connection as a hard earth fault, preventing the system from operating.
How Does HOEM Work?
The HOEM is a socket inlet on your home wired to a HOEM sub-board installed near your existing switchboard.
HOEM will not power your whole home. It is designed to power a small number of circuits that won’t overload the car’s modest V2L power limit.
The HOEM device uses a clever combination of off-the-shelf components. Primarily, a changeover contactor swaps your selected circuits away from the grid supply and onto the car’s V2L output.
The onboard inverter in a car is a limited source, so there is also an AS4755 load-sensing relay.
This relay is adjusted to your vehicle’s specifications. Should household demand surpass what your car can provide, it temporarily drops off non-essential circuits. So when you put the kettle on, the V2L inverter doesn’t cut out, and you don’t have to trail out to the garage to reset the V2L supply.
HOEM call this ‘V2HL’.
15amp socket inlet on the left, HOEM device on the right
Hallelujah, There Is No App
Connectivity for HOEM consists of an extension cord. That’s it. No internet, no app, no worries.
Integration involves activating the V2L supply on your vehicle and simply plugging the cord in.
Simply plug the cord into your house…
…and into the car.
If the car battery runs down to the point it should disconnect the V2L inverter, the HOEM device will default to ordinary mains supply.
There are already happy campers out there (I’m assuming Frank means energy bill savings of 6kWh per day)
It Is Legal, Isn’t It?
The HOEM device has instructions for your electrician using drawings extracted from AS3010, so it’s compliant with a conventional generator inlet socket and changeover switch arrangement.
It’s also compliant with the upcoming AS4777 standard for alternate supplies from inverters, once it’s formally adopted.
New AS4777 standards should solve some problems.
Installation Is Flexible
The HOEM device is supplied as a kit, meaning you and your electrician can decide to bolt on externally or seamlessly integrate the parts.
The car may supply 2kW to 3.5kW, whereas the average house has 14.5 kW available from the street. So you’ll also have to decide what’s essential and what will save you the most money overnight.
Extended Capacity With Smart Energy Sharing
Typically, this type of modest backup system would power your lights and fridge, but HOEM allows you to choose an extra circuit — a small air conditioner or pool pump, for example. This non-essential circuit will drop out temporarily if the V2L function is overloaded.
There is also scope for a WiFi-controlled relay, allowing remote switching, timer functions, or a kWh meter so you can track your savings.
HOEM Will Sell Like Hotcakes
The HOEM device costs about $900, less than 10% of a Wallbox Quasar bidirectional charger.
Installation could be $300 or $3000, depending on where your car is parked and if you need a dedicated wiring run for appliance(s) you want to run off the car.
While any competent electrician should be able, my advice would be to engage a savvy home automation expert and take the opportunity to overhaul your switchboard for solar, consumption monitoring and hot water diversion too.
The Take HOEM Message
Electrically, the solution on offer here is super simple.
Technically, it’s switching less than 20amps, so there are no network compliance problems.
Ethically, the people selling it aren’t trying to patent the idea to make a motza; rather, they use a “cc” web domain to raise awareness about Cocos Islands, Australia’s most climate change-vulnerable territory.
If you can charge at work and come home with a near-full battery every night, you can run the house on the stored sunshine and use the company fuel while avoiding peak evening rates.
HOEM makes it easy to save money day-to-day, but it’s when things go pear-shaped — when there are grid outages due to fire, flood or other disaster — the benefits will be priceless.
If you are interested in HOEM, their website isn’t great – your best bet is to call Russell on 0418 810 205 or email [email protected]
About Anthony Bennett
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Hi Anthony
I wasn’t clear whether this was grid forming or not, as we have a lot of outages in the middle of the day. We also have a PHEV, so I wondered if we could run it with the engine on, if the battery got low?
Thanks
Adrian
Nice, although it’s still one-way electrical traffic.
Charging at work to discharge at home feels like a small subset of EV owners to me.
Anyone who typically charges at home won’t find it overly convenient, people will quickly lose interest in constantly swapping over charge and discharge plugs.
But as a useful backup supply for power outages it’s pretty neat. Any typical backup generator set up pretty much has the same capability, except for the load and supply switching management which is a nice touch.
There are some working on devices which draw power directly from the EV’s DC supply and can potentially provide far more power than the limited output of the car’s on board V2L inverter. Keeping my eye on those.
But “V2HL” is a far cry from V2H or V2G. Bi-directional with the same plug left in the car’s charge port is what’s really going to be of most interest to people. That’s some way off though, especially at a sensible price.
My home battery is off-grid and so it’s easier for us to use V2L as a supplemental charge source for the home battery rather than power the home directly. The off-grid inverter can cover much more demanding loads than V2L (in my case up to 8 kW).
Indeed it’s doing this right now as we had a grid outage today (some scheduled maintenance on the local poles and wires). My V2L is providing a supplemental 1.6 kW back into the home battery using a battery charger, which is just as well since the day is very cloudy and there’s not much PV generation. I had pre-filled the car with tariff-free energy on the weekend, so it has ample storage to get us back to cover peak period.
I hope it does well and the developers can work on even better options in future.
I agree , V2L works best for me as the AC in of an offgrid Energy system. This way it’s assisting the inverter depending on battery state, solar production and current loads. Using as AC feed in the hybrid offgrid inverter allows power limiting as you usually can define the max current of AC in using inverter controls . Also as a backup AC source you are not overly cycling the EV’s traction battery so hardly reducing its life.
Charge the EV at night @ .08c (or $0 between 11am and 2pm on my solar/EV plan) and tap the battery when I’m being slugged .36c. Swap the plugs over when I’m heading to bed if and when the car needs juice. This should work for me. Not as good or versatile as a home battery but a much smaller outlay. One concern is what happens when my energy provider changes its tariffs? I’ll jump off that bridge when I come to it.
How does your vehicle get charged in this situation?
Cheers
Gib
Unfortunately with this configuration you’d have to manually swap charging cables from your regular grid to vehicle charger to the HOEM charger when you want to change from in to out and vice versa.
It’s easier for off-gridders. (Yeah, only 2% of consumers, according to the ABC, but a few more each week, as the sticks are discovering the 21st century.) I can just plug the MG4’s V2L cable into the generator input, after pushing Rhonda aside. And so long as I do that well before the house battery is flat, the 2.5 kW MG4 limit can trickle in, while the battery takes the hit of water supply pump and kettle at the same time. Cost: One V2L cable at about $250. (This may the only case where off-gridders get off lightly.)
Incidentally, my nominally 1.1 kW Grundfos water pump has a Variable Speed Drive, so soft-start. It generally only draws 400 – 500W, so the V2L should be able to drive it without battery assistance, I figure.
Maybe in winter. The charging station says it’s put 292 kWh into the EV in a couple of months, so far all one way. With no feed-in possibility, that and the HWS are the only available energy stashes. Today’s the first day with “Automatic” mode (surplus solar only) charging working on the Victron charger – after a firmware upgrade and a good bit of tweaking. (Marvellous service from the wholesaler and installer now.)
The prospect of never starting the generator again, on top of thousands of km of driving on pure fossil free photons is very very nifty. Once the climatologists admit that climate change always outpacing predictions is due to 45 of their 55 climate models underestimating the Equilibrium Climate Sensitivity, and a choice to ignore the more accurate models, we might have to shift up a gear or two in mitigation and adaptation. More solar, batteries, and high ground make a useful mix. Ample tank water is good too.
My MG4 is amazing for off grid use . My el cheapo all in one inverter and smallish solar charges house batteries them heats hot water then charges MG4 at 100km per 4 hours charging. When crappy weather the MG4 tanks on AC input duties. The mg4 allows 50% of battery to be discharged V2L and thats around 30kwhs so as a boost to soft bad weather solar production can last for over a week running essential loads.
My MG4 (Essence 64) allows discharge from 100% down to 20% SOC. Just slide the discharge controller on the car’s control panel screen to change the minimum discharge setting. If our car is fully charged we have over 50 kWh of capacity to play with.
Thanks for heads up re changing max discharge on MG4 . Ill try try again, last time the slider didn’t seem to want to go lower than 50%
Hi Lyle
I couldn’t respond to the question below as the nested discussion options in this forum has limits, so am responding here.
Your question:
“Can your new primary AIO charge the house battery via (excess) solar at the same time as secondary AIO ( in role as a V2L battery charger) is connected and running?”
“This scenario would occur in bad weather where solar on primary AIO is not enough to run loads and house battery is contributing to loads and you are bolstered house battery with secondary AIO powered by V2L. But sometimes cloud cover thins and solar production exceeds load and primary AIO starts charging house battery too.”
The simple answer is yes. It’s no different to having two inverters or two charge controllers connected to a battery.
IOW my primary AIO can be charging with the solar PV connected to it (or as mine often does, operates in utility pass through mode and charges from my grid PV system), while the second charger is also charging.
Naturally you will want to ensure the combination of both chargers can’t exceed the charge current limits of your battery. In my case that’s not particularly difficult as the total combined max charge current setting is lower than what the battery is capable of handling. The BMS is still there as a line of defence in case of user error but best if it never needs to trigger.
It could also be managed with automations in Home Assistant but as always best to have a default fallback setting in case it decides to go offline.
I don’t plan to use this often, most likely as an extended capacity option for outages. But if the weather is lousy and we have a free tariff period to get some extra e-juice into the car, then why not? I tested mine overnight with an extension from the garage and it worked fine (I did the voltage drop check) and plan to get a suitable thicker gauge extension. In scenarios where I just want to extend the operation of the home battery, then all it needs is a 550 W or an 1100 W “trickle”.
Thanks Alex for comprehensive explanation of how you have connected AIO pri & secondary to 1 household battery.
Thank again
Eric, how did you get around the following point that Anthony Bennett mentioned in his article above: “Why V2L Can’t Directly Power Your Home”?
Anthony says that “You can’t plug a V2L car directly into an Australian switchboard if there’s an earth leakage safety feature in the EV’s V2L output. The car’s safety mechanism interprets the home’s Multiple Earth Neutral (MEN link) connection as a hard earth fault, preventing the system from operating.”
This exactly the problem that I have when I plug my BYD Atto3 V2L cable into the generator port of my off-grid Victron inverter. It trips out.
Erik, our MG4 is right now supplying charge to our off-grid home battery. Just a steady 1100 W for now which is covering the consumption of our two homes plus a little into the battery.
We had a scheduled grid outage today, so not a lot of charging was possible and it got cloudy once they’d finished. Because it was planned outage I had already topped up the car using the free tariff period on the weekend.
Not something I plan to do often but I made today’s planned grid outage an opportunity to do some experiments.
I’m using a spare AIO inverter/charge controller to bridge the V2L supply into the home battery. All remotely viewable/controllable via Home Assistant.
Alex, you’re sneaking the power in as DC via a battery charger? That’s an interesting way. My brother’s hybrid installation has a generator input despite being on-grid most of the time, and here I’d be nuts not to have it. But I have a massive old 60A LA charger I could cobble suitable LFP absorption & float regulation onto. But I might just use it with the tired old ride-on mower once it’s converted. (I have more immediate need for stashing the generated energy, than pulling it back – only 2 kWh battery drain per night here.)
Like you, I’m not keen to regularly use the EV battery for domestic loads, but LFP durability appears to be sufficient to outlast the car already, and new batteries are coming with even longer cycle lives. Your active EV back-up situation will soon be more common, weather and network experts are saying.
It’s expensive to be ahead of the pack, but how many lights are on around you when there’s a longer outage?
Erik, yes, I use a spare all-in-on (AIO) inverter/charger controller I have and it is connected to our off-grid home battery. It’s turned off most of the time.
I plug the AC output from the car’s V2L adapter into the AC input of the AIO, and then I set the AIO’s DC charge current setting to whatever I want (mine increments in 10 A steps) which equates to approximately 550 W AC steps. I’ve decided that 30 A charge rate from V2L is a sensible limit, which draws 1.65 kW from the car.
But any plug-in charger suitable for a 51.2 V LiFePO4 battery would work. I just happened to have this spare AIO. It’s a 4 kW unit I used to use for outage backup before migrating to an 8 kW AIO to run the home all the time.
Indeed I ran the V2L overnight as a test and it was supplying a steady 1100 W into the home battery for 11.5 hours.
Meanwhile our main 8 kW off-grid inverter supplies the home overnight from the battery. 1100 W of supplemental power from the car was enough to cover household loads plus put some charge back into the home battery after a day with grid outage and cloud.
This would be an infrequent thing but it’s nice to have it if needed.
Yesterday just happened to be the day I decided to test it all out. I knew the grid outages was happening so decided it was an opportunity for some experiments and it worked very well. I already have a lead acid battery reserve capacity on hand for extended outages so I don’t expect to need to do this often.
I’d filled the car up with free energy (0c/kWh super off-peak tariff) on the weekend, so it didn’t exactly cost much. It’ll recharge today from solar PV which will cost us a grand total of ~20c.
Love your set up and its similar to where my offgrid system is headed. Im upgrading my 3.5 kw AIO to a 6kw AIO to better handle house loads . This will free up the 3.5kw AIO for V2L charging of house battery duties like you have done. Ive a question re the battery connection.
Can your new primary AIO charge the house battery via (excess) solar at the same time as secondary AIO ( in role as a V2L battery charger) is connected and running?
This scenario would occur in bad weather where solar on primary AIO is not enough to run loads and house battery is contributing to loads and you are bolstered house battery with secondary AIO powered by V2L. But sometimes cloud cover thins and solar production exceeds load and primary AIO starts charging house battery too.
By the way Erik, we can’t see neighbours from where we live. But grid outages are relatively common in our area (rural power networks) hence having an off-grid backup system.
Since November 2018 I’ve kept stats on outages which last longer than 5 minutes (but plenty more are shorter and not counted).
# OF OUTAGES 75
YEARS 5.4
PER YEAR 13.9
Days since last outage 1
OUTAGE DURATION
Total 134:25
Annual avg 24:50
Average 1:47
Median 0:50
Longest 19:00
Shortest 0:05
Most recent 1:50
Alex, for an eyeblink I read your “OUTAGE DURATION” as “OUTRAGE DURATION”. You’d be justified, I reckon. That’s atrocious, almost designed to push folk (semi-)off-grid.
Back in the day, getting onto the 32 Vdc electric lights, leaving behind the candles and kero lamps was great. With this solar stuff, we’re making an equally significant transition I feel. (More so for low lying islanders, were it not that climate overshoot will be beyond curing with gumboots.)
So this could be used to plug a small generator into as well or instead of a car
BYD cars in Australia come with a V2L cable that simply has a 240V powerboard, rated I think to 10amps. So.. in the rare event of a prolonged blackout (and our Tesla Powerwall is drained)` then I would need to run a long heavy-duty extension cable to the fridge and any “essential” appliances. I already have a short extension cable to the fridge so I can easily do the changeover (don’t have to pull the fridge out to reach the GPO).
Evidently the HEOM system requires a compatible vehicle that is already capable of V2L so it seems a bit over-the-top to install the V2H kit, unless you have frequent blackouts.
BYD support V2L sure, but if you use this for V2H then you’ll invalidate the battery warranty in your car!!!
I read that the V2L cable won’t work in a house that is 3 Phase. I have just upgraded to 3 Phase and bought the BYD 5 months ago – only to learn the V2L will now not work. I thought I would put this out there for others who are unaware of this.
P.S: I am not technical
Hi Jo,
That’s not quite right.
Cars don’t have 3 phase V2L but when you install a HOEM device, or a single phase hybrid inverter for that matter, you’ll select a limited number of single phase circuits powered by the battery/car.
So for all intents and purposes you can use the HOEM device, a generator, or a hybrid single phase inverter as intended… but not to power 3ph loads.
https://www.solarquotes.com.au/blog/3-phase-battery-trap/
Thanks Anthony.
I will discuss this with the guy who will install a faster charger soon-ish- like when I get my solar panels working, lol.
Cheers
Jo
BYD are 3.6kw so 15a, the sockets that it connect to are 2x 10a sockets, which on a 20a breaker could both draw 10a, but on the BYD you could draw 10a and 5a or any combo up to 3.6kw
Could this same setup be used to provide a hybrid off-grid inverter and battery storage solution?
Ie using one of the retail available all-in-one units such as Bluetti or EcoFlow, etc. which is then connected to a solar array? If the battery is low etc it reverts to grid, but provides automated backup?
Could an EV then be used to supplement charge to that battery?
Would this be allowed??
I use a EV’s V2L on a all in one inverter/ mppt regulator charger/ATS. Works great
Hi Team, thank you for the article, very informative.
It triggers one question:
In principle, should it be feasible to have a solar panel array of say 5kw, and an inverter of say 8kw nominal capacity, which could take up to 5kw daytime input from the solar array and simultaneously up to 3kw from the V2L output of an EV (and at night time take say 5,6,7,8kw from the EV)?
The key question being why can’t I have an inverter with an accessible DC in connection to plug my cat into? Or else modify one to do so?
How feasible is that, and what would be required for the regulatory boffins in Australia to make it happen?
Thank you
Hi Borg,
There’s no approved DC charger available for domestic duty in Australia. Sigenergy claim to have developed one but until the revision of AS4777 is finalised and released we are all waiting. Once that’s live and they get the IEC standard sorted for CCS2 with bi-directional charging then it could be a very different situation.
Thank you! Fingers crossed!!!
6Kwh currently costs me under $1.50 from the grid. With a 10c per KWh FIT forgone to charge the car, I’d save 90 cents per day or $326 per year.
Not sure what you’re calculating, Ren, but driving the average 15,000 km per year, using a slightly optimistic 1,500 L of petrol in an ICE vehicle, costs around $3,000 p.a. Replace that with free photons, and the saving is $3,000 minus FiT for 15000 * 0.17 kWh. At an achievable 6c/kWh, that’s $153 to deduct. That gels with the $2700+ saving reported recently on another SQ blog.
That’s why EV sales are taking off in Melbourne’s outer suburbs. ICE commuting has whiskers on it when there’s a mortgage and kids to feed.
Wtf? The potential savings of the device this article is about, not an ev. Did you write this🤣 one of the images: ‘There are already happy campers out there saving 6kwh per day.’
“Free Photons?” I love the way everyone seems to overlook the capital cost of installing Solar/Batteries/Inverters/L2 EVSE etc to focus on the low cost of solar exclusively. In your example, the ICE driver is only up for the cost of petrol and maybe a credit card fee every time they tap at the servo. They didn’t have to pay for the petrol pump or infrastructure. Or a hefty premium for the EV over it’s ICE sibling. Whereas the EV driver pays a hefty premium for the EV and either pays through the nose for public charging and/or has paid for rooftop PV, a home charger and probably batteries. None of that is free.
If you really want to be accurate when working out your savings, total the capital cost of your PV, batteries etc and divide it by the expected lifespan of your inverter/PV/Batteries. Say ten years. Subtract that from your $2700 savings and you’ll get a much different figure I suspect. Don’t forget the extra costs for insurance, EV rated tyres and apparently, the massive depreciation, especially if you’ve just bought a Tesla Model 3 and paid full freight. Don’t kid yourself you’re saving money driving an EV.
Full disclosure – I have 20kW of PV, 2 x PW2, L2 EVSE and 3 x EVs in my household, so I’m no EV hater, in case you’re thinking that. Just a realist when it comes to the true cost of renewable energy.
However, back to HOEM, it is interesting, but I think for an extra $1500 I’d be more interested in a hybrid Inverter like the DEYE to have the flexibility to charge my PW2s from my cars via the inverter and let the PW2s power the house loads. My V2L has a max rate of 3.6kW and I get free charging at work, so I would think I could get that supplied and installed for under $5k max, which beats adding another PW2 for $11600 or more.
Yes, rooftop PV energy is not free.
The lifetime amortised cost of our home’s PV energy generation will be ~5c/kWh.
That said, for some people with export limitation their marginal cost of generation can be close to zero when they can add load (e.g. an EV) as the generation would not otherwise have occurred.
Our EV (MG4) was cheaper than the car it replaced, we downsized a little because of a change in circumstances, so made the leap to electric. Got in early enough so NSW govt rebate paid for the EVSE. It automatically manages charging using the cheapest energy (either excess PV or during free energy tariff periods – so far costing 93c/100km compared with ~$14/100km for our last car).
Per km, DC fast charging on highway trips is about 10-15% less than our fuel costs were but a portion of a trip is supplied from home charging (leave full, arrive back with partial charge).
Home charging is an order of magnitude lower cost per km than fuel.
The maintenance, while not zero, is going to be substantially less.
Insurance in our case was actually lower but not substantially so.
Depreciation will be about the same, and tends to revert to the mean.
It was actually the quoted maintenance bills of $5k on a car with <50k km that flipped me.
For those who can arrange a novated lease (not us), then an EV under the LCT threshold is a no brainer as they are treated very favourably. A Model 3 is cheaper to lease than a Camry.
Thank you Anthony. I am not sure I understand exactly how this system functions to decide if the benefits outweigh the costs:
1. What is the transfer time for the contactor and power limiter when switching between grid and V2L and vice versa?
2. What happens if there is an 5A over load on the essential loads circuit? Will the Power Limiter temporarily turn off all essential loads (wife unapproved) or will it signal the contactor to switch all essential loads to grid supply within say 20-30 ms (wife approved)?
3. How does the power limiter shown in the photograph temporarily drop non essential loads? Is this self contained (multiple relays, CT meters and load outputs) or does it signal the dry contacts of a second relay, e.g. the photographed Shelly Pro 1, to temporarily disconnect the non-essential load?
4. What’s this 20A switching compliance rule and where / how does it apply? Does it apply for.example on Ausgrid network in NSW?
I have a generator inlet circuit, changeover switch, vehicle to generator inlet heavy duty lead, current limited circuits (lighting and Power) but no A/C, or stove installed 18 months ago by an REC, that runs fine with small generator but did not work with the Atto3 due to the earth system issue explained in the article. This may be the solution I was looking for. Interested in any electricians in Victoria who want to give this a go, given the one I used was not 100% across what would work at the time.
How would this integrate with a hybrid inverter system that already has a home battery installed?
Would it be as simple as using installing the HOEM on the same circuit (no including ovens/aircons) and it would supplement the feed?
I have Sungrow 9.6kWh battery already and it’s flat before midnight with our usage. I’d love a HOEM to supplement with our Ioniq 5!
I have the HOEM system installed and about to add a 10.1kWh battery to our house. How HOEM will work with the battery is that the circuits that are set up on HOEM will switch over and be powered by the EV (BYD Seal in our case). As soon as you disconnect the EV from HOEM those circuits will switch back to being powered by the house battery. Basically it simply takes some burden off the house battery.
I was previously aware of this HOEM device and have actually shown it to my electrician for consideration and unfortunately their take is that it’s not legal to install.
Mainly on a technicality with AS3010. That standard that HOEM claims to comply with is only applicable to generators powered by an internal combustion engine. Clearly an EV does not have a combustion engine so therefore it can’t comply as it’s not even covered by the scope of said standard.
Most DNOs require you to inform them and seek approval for installation of a generator change over switch. And essentially the sparky has to tell a white lie by saying the installation is for an AS3010 compliant generator when this isn’t accurate.
This is just a technical hiccup there is no safety risk, but it was enough to put me off the concept until a proper fully approved and commercial solution becomes available.
Hi Barry,
I’d push back on your old mate.
If you buy a Honda 2.0i or 3.0i or any number of other “generators” the supply comes from an inverter. That’s what the i stands for.
I know they can be conservative but if your electrician is scared to hook up an inverter supply, because the box is the wrong colour, then that’s the height of pedantry.
It complies with the new standard for inverter supplies anyway.
Hi Anthony,
I have already been through the motions with my sparky, and he is not budging. But he took the time to explain to me his reasoning and I must say it seems very convincing to the layman.
His argument is that you cannot pick and choose what parts of a standard to comply with. You must comply with every part of a mandatory statement in an Australian standard. And AS3010 very clearly says in the scope, that it applies to “electricity generating sets driven by internal combustion engines”
Obviously, an EV has no internal combustion engine. So it falls outside the scope of the standard right from the get go.
He agrees with me that HOEM seems like a very clever idea, but its enough of a grey area compliance wise that he wasn’t keen on risking his license on an installation.
If you have an iron clad argument for how an EV is somehow actually a petrol generator I would be happy to pass on your thoughts.
Hi Barry,
At the end of the day HOEM is simply an automatic changeover switch with a socket inlet. That’s what your certificate of compliance says. End of story.
In reality the energy source for the prime mover is irrelevant, and arguably an overstep by those writing the standards.
If it plugs in, and it’s below 20a, the installation of the changeover switch is compliant.
What you as a customer plug in is up to you.
It could be petrol, LPG, diesel… you could have a methane fired boiler for an external combustion engine. (ie a steam engine like Torrens Island power station or the Powerhouse Museum in Sydney)
Your electrician is arguing semantics, bless, as a trade they are prone to do that but he’s not obliged to label the socket inlet as “Internal Combustion Power Only”
Saying it must be internal combustion engine is a bit like arguing that coal fired power stations are actually just running on stored solar energy.
You could equally say the on board inverter in a Mitsubishi outlander PHEV is driven by internal combustion, when in fact it’s an inverter and battery, charged by any number of sources.
The new AS4777 diagram shows inverter supplies because the standards are being dragged into the current century, where inverters are already plugged into buildings via socket inlets every day.
There’s an inverter inside Honda 2.0i, has been since they were introduced… it just happens to have a petrol prime mover.
Electrcians argue a lot about “should” or “shall” because they end up being key words in the standards. If you want to read AS3010 and can find the part that explaining generators “shall be internal combustion” then we’ll just have to wait for AS4777.
I hope that explains it.
A slightly less complicated solution that you can rule out is the installation of one or two appliance inlets on the inside of your garage with a GPO on the other side of the wall inside the house for easy access.
I have seen this promoted on other blogs.
Unless you install protection (no not that sort of protection) between the inlet and the gpo, this is not compliant. Running a lead through the garage personal entry door obviously is.
You are only asking for a generating inlet. Your electrician cannot reasonably be expected to ensure that only internal combustion generators are ever plugged into it. Just as a sparky can’t prevent their customers only plug in appliances with an RCM compliance mark. His responsibility ends at the inlet, I would have thought.
This can be also done with a changeover switch in the switchboard. And a water pump can be run from the car. I’ve had this installed for a couple of years now and is a lifesaver during power outages, whether planned or unplanned. A 73kwh car battery lasts for days with prudent usage.
Cupra Born is V2G FYI and will work with quasar box next generation V2G version using CCS instead of chademo.
Can you give an example of an EV that has earth leakage detection built-in to the V2L system? I understood that all V2L systems operated as isolated systems (just like a generator).
Hi Ben,
I have had a customer who’s had a conventional changeover switch wired and his Kia(?) won’t play ball with it. If I can find the support ticket I’ll ask him about it.
Given most workers can’t get carparks, and most carparks don’t offer recharging, this seems to be quite a niche option. And how does it impact warranty? Some companies void the warranty if the product is not used as intended e.g. graphics cards used for crypto mining as per SQ’s 1st April article. Given EVs powering homes is so niche perhaps it’s not yet covered, but if a lot of vehicle owners start regularly draining and recharging their EVs to power their homes, might EV manufacturers rethink exactly what is covered?
Hi George,
The cultural shift we need is that cars get plugged in during the day, no matter where, just a 2kW power point will do but it needs to be every car everywhere, that’s how we get to net zero.
Has anyone done any research on what these extra discharge cycles will do to the EV battery life? And how will it affect the car warranty?
As a retired electrical engineer I am a bit disappointed about the life of lithium chemistries vs nickel, despite the obvious advantages.
1,000 cycles on a battery capable of doing 400km per cycle isn’t enough for you?
Depends on battery chemistry. A NMC lithium traction battery has around 1500 full cycles whereas a Lifepo4 typically has over 3000.
Regardless of which chemistry you have , I think the intention of V2H/V2L is boosting weak grid mains/ grid outages & boosting offgrid ES , like ICE genset does when solar hasn’t been enough to run the loads.
You only have 2.5 – 3.5kw depending on vehicle specs so its a helper or a runner of critical loads used sporadically. So reduced battery life isn’t a big factor.
The NMC battery in my car will outlive the car, something like 500,000 to 700,000 km to 80% state of health.
LiFePO4 batteries will be well beyond a million km before reaching that level.
In reality for the vast majority, calendar ageing will kick in before energy cycling causes much battery degradation.
Discharging an EV battery at ~0.01C for V2L use isn’t even noise as far as the battery’s lifecycle use. It will barely notice.
I used my EVs V2L for 5 days whilst camping. Ran fridge, tv, lights and cooking. It hardly moved the traction battery’s SoC at all , only 3% in 5 days.
Hi Anthony
Just wondering if people have had any luck contacting HOEM? I’ve tried calling and emailing with no success. I’m a licensed electrician with a BYD Atto and a BYD T3 van and I’m keen to install this and see how operates.
Hi Phil,
I’ll soon find out for you.
Cheers for the heads up.
Hey Phil,
Did you end up getting in touch as I have also tried and had an initial response asking for some information, which I provided but it all fell silent after that.
Paul
Hi Paul,
Try Ewan on 0417 869 161 and see if he can help.
HI Phil,
I contacted HOEM via the hello@xxx email address at the bottom of the article and got a response a day or two later. I would add that I also tried the mobile first but didnt get a response.
And just to add, my enquiry was about compatibility of the HOEM with a Nissan Leaf ZE1. Unfortunately, its not but I wasnt given a reason. Maybe its the earth leakage issue or maybe not. Disappointed regardless.
Sorry if this is a dumb question, could this HOEM device also allow your solar system to continue generating in the case of a grid power outage or is that too much of a stretch?
nope – you need a grid-connected battery for that
Newbie to this, so excuse my question if it is a bit basic. I have a Genesis GV60 which is the same architecture as the Kia EV6 and Ioniq 5. I currently have 2xPW2 at my home 19kW of panels and 2x inverters (10kW Tripower and 5kW Fronius single Phase) I was considering adding a 3rd PW2 but am looking at the feasibility of utlising the V2L capability of my EV.
My thoughts were that on occasions when either the PW2s are exhausted or the is a grid event when the FIT hits $$ (I’m with Amber on wholesale pricing) I would like to plug in my EV either to charge the PW2 or supply the house while the PW2 is dispatching. I understand that in the first scenario, the V2L charging is limited to 3.6kW max and my batteries can discharge at 15kW, but when I’ve been able to get a FIT of $17 kWh or more, I want to export as much as I can and if I have the EV backing them up, that will supply enough for the house. Is this possible?
We actually have 3 x EVs in our house (2 x Kia Niro with V2L) so if I can utilse the V2L as V2H it would be more cost effective than adding a 3rd PW2.
Hi Rob,
With the new AS4777 coming soon, my initial thoughts are that your power walls are the high capacity, bidirectional, supplementary supply, suitable for control in a VPP.
If you used a HOEM device (and your car to power it) then circuits downstream of the power wall would be given an alternative supply, leaving more energy left in your Tesla battery to do with as you please.
This gives you the emergency capacity of using the cars in an outage but also means you can harvest kWh from the car on a regular basis.
Bear in mind that HOEM isn’t bi-directional. You would ideally charge at work during the day and siphon off some energy at night. There’s no way to automatically change from the car powering your house, to grid recharging the car, if for instance your TOU pricing changes at 1am.
Thanks Anthony
The alternative to this is to install a Hybrid Inverter like the DEYE SUN-5K-SG04LP1-AU that would allow me to just charge my powerwalls using V2L. The EV plugs into a socket that is connected to the Generator input on the inverter The advantage of that is that it gives me more flexibility to direct the vehicle’s load to the battery or the house circuits, as I understand it. This article explains it in detail: https://wattever.com.au/power-your-home-from-an-ev/
So if I want to add to my current capacity, I have three options at present as I see it (in order of most to least expensive)
1) Install another Powerwall. This is the costliest option at around $11600 installed, but it’s neat, and it works. No potential issues of degrading my car battery but on the flip side – I don’t leverage the capacity of that car battery.
2) Install a Hybrid Inverter. Considerably cheaper than the PW2 option at around $2500 for the inverter and let’s say another $2500 for installation. A very flexible option that allows me to utilise the V2L to charge the PW2s and run my loads off the PW2.
3) Install a HOEM. Cheapest option, even assuming $2500 for installation. Less flexible than option 2 but a quarter of the cost of another PW2. It worries me that there is not much info out there about HOEM, and only marginally more about the inverter option.
Problem is trying to find a sparky that knows what they’re doing with either the inverter option or HOEM.
Hi Rob,
I’m not sure about the stability of a Deye inverter if it doesn’t have it’s own battery however you could do the same with a Selectronic SpPro and a smallish battery to maintain the fridge when you’re not home.
If you’re hunting for a tradesman then explaining a HOEM device is simply a generator changeover switch will make it less scary for an unfamiliar electrician.
Cheers
I get free charging at work, so on the three or four days a week I’m in the office, I am actually charging for free. That’s one of the reasons I’m exploring alternatives to another battery at home.
How long do you think employers and local government etc will keep providing free EV charging when EV users are found to be charging their cars to run their homes?
Hi Lyle,
When the spot price of electricity goes negative you’ll get paid to charge. There’s scope for people to attract customers or employees AND defray costs. Besides which it’s really just where the future of energy is going. Daytime charging is already the new off peak.
They’re cutting it out and charging as of 1/7. It was good while it lasted but I’ve always thought it ridiculous that someone else foots the bill for me to charge my EV.
HI Everyone.
Regarding with earth leakage detection issue tripping the V2L. Is it only in situation of plugging direct into house through changeover switch?
Deye hybrid inveter has generator inlet as secondary grid. Will there be same issue if connected through inverter generator inlet. (apparently it doesn’t need external changover switch as it switch automatically built in to inverter)
This article is pretty interesting read.
https://wattever.com.au/power-your-home-from-an-ev/
Great and concise information, thanks.
The photo shows an Ioniq 5 but the narrative refers to BYD Seal. Are they the same so far as V2H/HOEM are concerned?
Hi Cyrus,
HOEM will work with any 240VAC source. Have a look at their website for a table of vehicles which have an on board inverter for V2L output. Tesla owners can add an extra aftermarket inverter to get 240v output, but it’s limited by the input from the 12v system in the car.
You could even plug a petrol generator into the HOEM socket and still benefit from the current limiting function to prevent generator overload.
Hi,
This isn’t so much related to this persay, but would the new 4777 standards enable the use of used EV batteries as home storage?
Hi Andrew,
There’s going to be a lot of interest in doing just this, and so there should be in my opinion. Productive reuse is always preferable to transporting, grinding, reprocessing & remanufacture for new batteries, however it’ll have to be treated like a class 6 battery system under AS 5139 I think.
The caption to the photograph of the hardware, starts with “5amp socket to the left”.
Should that not be “15 amp socket” ?
All fixed thanks Brett.
How does that Hoem device get around the problem of the car’s inverter tripping out due to the MEN link in the main switchboard? Are they switching the neutral as well as the active so that it’s not connected when being fed from the inverter? That is usually a big no-no and AS3010 specifically bans it. The schematic you showed from the draft AS4777 shows a solid neutral connected all the way through.
Hi Jim,
Consulting the diagram included with the HOEM device shows just the same, with neutral connected permanently & MEN in place as usual.
If your EV was going to trip under these conditions, the only alternative I’m aware of would be to use an isolation transformer & treat it as a separated supply, the same way boats are isolated from earth when they’re plugged into a shore power supply at a marina.