[Australia] Looking for some home-charger feedback/opinions

[ReintjeWA]

We are in the process of building a new house. My commute will increase to about 110 km a day so I'm assuming I will be charging almost daily, especially if I want to use some excess solar power (I work in education so I'll be home by 4 pm most days). We are looking at 14kWh solar system, which apparently is the capacity on a dingy winter's day.

I want the house to have a 3 phase connection, this will allow us to have more solar generating capacity, a home battery, and I think it is simply the right thing to do with an ever more electrified future. The network provider has already confirmed 3 phase is possible.

Now the tricky bit that I would like to pick everybody's brain on is what do I do for a home charger? If I install a 22 kW EVSE, future proof etc. my Trophy 64 will only take 3.6 kW onboard. I think it's possible to put a 7kW single phase on one of the 2 phases, but from what I read online this can be a bit wonky.

Then on top of that, we are planning on swapping the car of my missus for electric as well, so should we then go for a dual charger? Maybe 2x 7kW on a two of the phases and leave one phase for the house? Seems a bit overkill. But if we are going with overkill, perhaps I should go all in and buy a domestic dc-charger, which of course then comes with its own drawbacks in terms of alleged battery deterioration, but could potentially use most of the dc solar charge.

I know I should have probably got the long range with the 11kW OBC, but it's too late for that now, and I still don't think the extra range was worth the extra money, but that is a discussion for another day I suppose.

Could one change a 3 phase connection into a single phase by some sort of extra fuse box, and then put the single phase charger on that? So the single phase charger ends up balancing the load over all three phases?

I will of course discuss all this with electricians (mot likely the ones that will be doing all the solar and home battery installation), I've just asked the builder to hook us up using 3 phase and to leave me enough room to add a ton of stuff on the switchboard.

Any other ideas I should consider? Any pitfalls I should look out for?

 

[siteguru]

Might be worth adding (Australia) to the thread title, as your requirements may not be relevant to folks from other geographies.

 

[T1 Terry]

Have you thought about a dedicated solar array and a set of used EV battery cells to build a DC to DC charger as well as assist in the house loads during peak power costing periods, like first thing in the morning and the evening peak? This would be off grid power, so the rules about what batteries you are allowed to use, don't apply .......

T1 Terry

 

[ReintjeWA]

T

Have you thought about a dedicated solar array and a set of used EV battery cells to build a DC to DC charger as well as assist in the house loads during peak power costing periods, like first thing in the morning and the evening peak? This would be off grid power, so the rules about what batteries you are allowed to use, don't apply .......

T1 Terry

The home battery will be a DC battery, so it can recharge from the solar panels even if the grid goes down (unlike say a tesla powerwall) the whole idea is to have electricity even when they turn the power off every time there is a bush fire. According to the Solar people, the battery wouldn't be big enough to deliver a worthwhile charge to an EV, but then I'm not planning on doing that anyway.

But if I understand you correctly, you are saying a solar array with no grid connection, that is indeed an interesting idea.

 

[Coulomb]

We are looking at 14kWh solar system, which apparently is the capacity on a dingy winter's day.

Do you mean a system with 14 kWh of battery storage, or a system with 14 kW of nominal panel power?

which apparently is the capacity on a dingy winter's day.

Solar systems are usually quoted as peak power, about equivalent to clear skies near noon in summer.

If I install a 22 kW EVSE, future proof etc. my Trophy 64 will only take 3.6 kW onboard.

No, it should take 6.6 kW from one phase: 27.5 A at 240 V.

I think it's possible to put a 7kW single phase on one of the 2 phases, but from what I read online this can be a bit wonky.

Two phases? Your MG4 64 has a single phase on-board charger, so it will only take power from one phase, through the L1 pin on the type 2 connector.

Then on top of that, we are planning on swapping the car of my missus for electric as well, so should we then go for a dual charger? Maybe 2x 7kW on a two of the phases and leave one phase for the house?

That's not a bad plan. Expensive, as EVSEs are crazy expensive for what they are. The phases will be unbalanced most of the time, but most homes are single phase anyway.

Seems a bit overkill.

It depends on your needs. If one of the cars has a more modest charging need, perhaps install a 15 A industrial outlet on a different phase to the big EVSE (7 kW or 22 kW). Then use a granny charger to charge the other car for the times when you need both cars charging at once.

You also need to consider if you can charge during the day, especially if you don't have battery storage. Maybe one EVSE can charge one EV during the day using mostly solar power, and the other at night on a lower tariff.

Could one change a 3 phase connection into a single phase by some sort of extra fuse box, and then put the single phase charger on that? So the single phase charger ends up balancing the load over all three phases?

No, that's not feasible, and not necessary in any case. It would take a lot more than fuses and breakers to achieve this. Basically, you'd have to convert from 3-phase AC to DC and then DC to single phase AC.

Any pitfalls I should look out for?

Remember that three phase installations are typically lower current per phase, say 60 A per phase instead of 80 A or 100 A single phase. So it's slightly easier to overload one of the phases than if you had a big single phase connection. Mainly you need to avoid two 6.6 kW EVs on the same phase; that would be 55 A on that phase, leaving only 5 A for other loads on that phase.

Also consider that the next EV may be three phase. EV batteries are getting bigger all the time, so the on-board chargers may get bigger as well.

 

[T1 Terry]

Not hard to find a big enough battery to equal or dwarf the EV battery, add in 3 Victron inverter/charges to wire into 3 phase if you really want it, if you must be connected to the grid, wire it into the mains supply side of the inverters and set them up to be solar/battery priority, grid secondary, or grid priority and on a timer that only supplies power when the grid is offering cheap power. You could even go a step further and add the V2L from the MG to assist over night when the power is off, via a three way switch, central position is off, so you have a break before make switch to change between supply sources.

The other option is to wire the inverters in staggered parallel, the first inverter goes into the second inverter mains supply and turn the charging off on the second inverter and any other inverters in the string. When the V2L is supplying the first inverter mains input, it will act as a charger if the house load is less than the supply, each inverter in the parallel string will cut in when the programmed max supply input is reached to assist the load, then drop out again when not required .......

Then, you could go completely off grid and add as much second hand solar are you wanted ..... you won't get the govt subsidies and those friendly solar installers might not be quite so friendly .... because you will be doing them out of a few $$, so you might have to offer that as a make up for what they'd loose .......

Being off grid, you can get the sparkies to do the house wiring and all the 240vac stuff and the high voltage DC stuff, and fit the solar panels yourself .... off grid "The Rules Do not Apply" wish I could remember what radio hit that line came from ....... I thought it was "One night in Bangkok" but I couldn't find it in the lyrics online

T1 Terry

 

[kenneth104]

Building a 3-phase output for solar cells will increase some costs
I think it is appropriate to connect to the grid, otherwise there will be a large amount of battery expenses
If you still choose to run the battery + solar panel method, a 7kW single-phase charger is enough, as long as you charge separately, it is more economical

 

[JoeBlow]

If I install a 22 kW EVSE, future proof etc. my Trophy 64 will only take 3.6 kW onboard

Just to confirm the above comment, you definitely can charge at ~7kW / 32A with a 22kW / 32A charger.

Just avoid 11kW / 16A chargers (such as the one MG sells) - this will limit you to 3.6kW on a single phase.

TBH though, most cars are limited to 1 phase / 32A charging lately, so I'm not even sure how "future proof" going 22kW actually is - my thinking is future V2G standards will eventually be mostly DC/CCS based.

 

[T1 Terry]

Found this You Tube clip added not long ago. Basically, the latest solar/battery/EV charging expo in Australia.
He waffles on about his own stuff etc, but interesting to see just how far the market has come over such a short period.



T1 Terry

 

[ReintjeWA]

Thank you all for your input, I indeed got my 22kW and 11kW mixed up.

We have no real need to be off grid, although it is a tempting idea, seeing as there are no mains water or sewage anyway.

 

[wattmatters]

We are in the process of building a new house. My commute will increase to about 110 km a day so I'm assuming I will be charging almost daily, especially if I want to use some excess solar power (I work in education so I'll be home by 4 pm most days).

I see you are in Perth, WA. This might be problematic depending on the PV array configuration for a couple of reasons.

i. It will need to be largely western facing PV array to enable this to work best. Even so, production after 4PM will be declining rapidly and it won't be long before there isn't enough solar PV output to cover the EV charging power demand. You will struggle to get anything like 110 km of range from solar after 4 PM.

Indeed here is a PVWatts estimate of solar PV generation after 4PM from an entirely Western facing 13.3 kW PV array with a 10 kW PV inverter in Perth:

It's pretty clear that there just isn't anywhere near enough PV generation after 4PM to be of much help to charge an EV.

Much of that small amount of late afternoon generation will be needed for the household to reduce grid imports. In summer the generation is greater but there's a pretty fair chance you'll also have the aircon going in the afternoon.

ii. the TOU tariff structure there is not favourable to importing power after 3PM, so you will need to be careful on how charging is managed in the late afternoon.

Synergy do have an EV plan, with lower off-peak rate of 18.9 c/kWh 11PM - 6AM. It also has super off-peak 9AM-3PM at 8.4 c/kWh which might be handy on weekends when it's cloudy. But the peak rates of 52.5 c/kWh from 3-9 PM are tougher to swallow.

 

[ReintjeWA]

I see you are in Perth, WA. This might be problematic depending on the PV array configuration for a couple of reasons.

i. It will need to be largely western facing PV array to enable this to work best. Even so, production after 4PM will be declining rapidly and it won't be long before there isn't enough solar PV output to cover the EV charging power demand. You will struggle to get anything like 110 km of range from solar after 4 PM.

Indeed here is a PVWatts estimate of solar PV generation after 4PM from an entirely Western facing 13.3 kW PV array with a 10 kW PV inverter in Perth:

View attachment 31829

It's pretty clear that there just isn't anywhere near enough PV generation after 4PM to be of much help to charge an EV.

Much of that small amount of late afternoon generation will be needed for the household to reduce grid imports. In summer the generation is greater but there's a pretty fair chance you'll also have the aircon going in the afternoon.

ii. the TOU tariff structure there is not favourable to importing power after 3PM, so you will need to be careful on how charging is managed in the late afternoon.

Synergy do have an EV plan, with lower off-peak rate of 18.9 c/kWh 11PM - 6AM. It also has super off-peak 9AM-3PM at 8.4 c/kWh which might be handy on weekends when it's cloudy. But the peak rates of 52.5 c/kWh from 3-9 PM are tougher to swallow.

Thank you for the information, that is very helpful.

I was considering the synergy EV plan, and just charge during the night on the low tariff, and use solar on the weekends. I figured the home battery could charge during the day, and then discharge during the high tariff 3-9PM. Maybe even have the battery pull charge during the super off-peak if we need to.

 

[decrep]

If you work, I think you need a battery, to store the daytime solar that would otherwise only earn you peanuts.
I'm thinking about it, but being retired, most of our needs are covered by daytime solar.

 

[Jamesrr]

I got a Tesla wall charger. I asked our son (how handy it is to have a sparky in the family) to wire it up to support the full 32A on each phase so it will do both 6.6kW on single phase and up to 22kW on 3 phase albeit the charger actually only supports 11kW on 3 phase ( I believe).
I get 10.6kW effective into our 77 Long Range.

P. S. The Tesla charger is the cheapest "good" charger you can get, albeit it doesn't have heaps of "smarts". It does support time of day configuration which is all I want, so it's "smart" enough for us.

 

[pollenface]

All I have is a 25amp circuit with 15A outlet and a 6-15amp charger from ebay ($200'ish).

When we first got the EV I thought we would need a 7.4kW charger professionally installed, but turns out we don't.

If you need a full battery, charge it overnight the day before. Any time you're home during the day, plug it in and let it charge from solar power.

 

[Ian Bittern]

The Tesla wall charger is single and/or 3 phase , too much solar system is just a waste of money and resources , you will get very little usable solar power after 4 pm during winter regardless of array size, you may get enough power on the weekends to charge your car/cars on solar in winter but I doubt it . do you have cheap overnight solar charging rates available to you ? these might be a better option with a smaller solar array, I have 5 kW and this provides most of my power 8 months of the year , but I would realy like to add 3-5 kW westerly panels for late afternoons to see if any more usable power can be found at the highest usage time. The Tesla charger is fast enough to give us control of charging when the sun is shining and save a lot of power costs .

 

[ReintjeWA]

The 14 kW solar array is actually not that much overkill for us, we are already pretty heavy users, and the new house will come with a hefty ducted aircon unit. I’m not at all worried the solar will be “too much”. The only downside to having more than 5 kW is that synergy won’t pay you for feeding back to the grid, even though they will take up to 1,5 kW if/when they want it, but honestly with the low feedback tariff that’s not exactly making me sad either.

 

[wattmatters]

do you have cheap overnight solar charging rates available to you ?

In Perth there is only one retailer, Synergy.

They have an EV plan but the peak rates are a bit of a gut punch given with solar PV most grid consumption will be during the peak period. Ref my earlier post:

Synergy do have an EV plan, with lower off-peak rate of 18.9 c/kWh 11PM - 6AM. It also has super off-peak 9AM-3PM at 8.4 c/kWh which might be handy on weekends when it's cloudy. But the peak rates of 52.5 c/kWh from 3-9 PM are tougher to swallow.