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Discussion Starter · #1 ·
Quite late to this myself but couldn’t see a thread - Indra are doing a trial of 500 to use their chadamo charger as a V2H charger. I think the main difference to previous V2G is the priority will be to use the energy to power your home, rather than send it to the grid - and if you have solar to put excess into the car for the car to later power the house when the sun goes away


Would be interesting to know if the charger will power the house in the event of a power cut
 

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Discussion Starter · #2 ·
To follow up, searching around and on facebook there is a private group called V2G-H UK - it seems like a few are already trialing using the Indra Chadamo charger as V2H and it currently works with the unit to draw power from the EV when demand increases, tho I think you have to own one or be lucky enough to find one second hand as I don't think they are available to buy new yet and its described as quite experimental - some are seeing some quite big savings even compared to the V2G trials

Aside from Indra the Quasar unit "sort" of works but you have to manually adjust the charge direction/rate - apparently a software update is coming end of the year
 

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When you look at what is going on with ChaDemo round the world and the number of home DC bi directional units (mainly japanese) it makes you wonder at the competence of the CSS folk who still can not seem to agree on a standard.
If a standard had been agreed at the start of CSS by now I suspect we would be awash with DC home units at various prices.
 

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Discussion Starter · #4 ·
When you look at what is going on with ChaDemo round the world and the number of home DC bi directional units (mainly japanese) it makes you wonder at the competence of the CSS folk who still can not seem to agree on a standard.
If a standard had been agreed at the start of CSS by now I suspect we would be awash with DC home units at various prices.
It does seem to be a bit of a clanger by the CCS lot that Vehicle to Grid wasn't considered - it seems a very clever way of using already existing batteries to help smooth out your power usage and yet another benefit of having an EV over other cars, especially as a second car which spends more time at home

Hopefully they'll sort it soon - the wallbox 2 I think has CCS and should be coming soon?
 

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There have been a few trials of V2X technology. In the ones I saw, you were on the hook for the installation cost (~£5k) if you didn’t plug in before 6pm on 50% of days. There was a cost to keep the kit at the end of the trial. Worth checking carefully what you’d be signing up to.

The first phase of the trial is for Chademo so worth considering if you want to tie yourself to this technology. Newer cars don’t have it so you could be stuck with a charger that not only doesn’t do V2H but can’t charge a subsequent car at all.

The subject of powering the house in the event of the failure of supply is an interesting one and one that affects not just V2X but static batteries as well.

First consideration is load management. The inverter isn’t going to be able to support all of the load in the house so your going to need to decide which circuits to support during an outage. Those need to be rewired so that they are supplied via the inverter. If you’re thinking about keeping loads like computers going, remember, this isn’t a UPS so there may be a break in supply. You then need to know what happens if the load is too great for the inverter. If the power fails whilst you are drawing a lot of power, will the inverter just shut down, leaving you with no power anyway?

The next challenge is earthing. In most houses in the UK, earthing is delivered by the electricity supplier. You can’t depend on that earth being present in the event of a power cut so you need your own. You then need a method of making sure you don’t connect your earth to the supplier’s earth. This should be in the inverter but, certainly in the case of static batteries, that has not always been properly considered. Without proper earthing, you are in danger of losing your protection against electric shock in the event of a fault.

Last is over current protection. The fuses/circuit breakers in your consumer unit are based on having a very high capacity supply. The reason the electrician needs to measure “source impedance” is to make sure that the supply can deliver enough current to operate the protection. An inverter that can deliver up to say 7kW will happily deliver 32A into a fault in your wiring without ever being able to operate the fuse. For context, a 32A MCB will take 5 minutes to operate carrying a fault current of 50A so effectively the protection you currently have is no use if the supply is from an inverter.

All of this is solvable but (1) it’s pretty unlikely that the trial installer will going to do any of this for you and (2) even if you decide to spend the money on reconfiguring your wiring to get power outage protection, I wouldn’t trust a domestic-installer-who-calls-themselves-an-electrician to do it.
 

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Discussion Starter · #6 ·
All good points, am no expert but my understanding from watching a few videos

1) Chadamo chargers talk about peak power output of 6Kw, the Quasar is 7.4kw - IIRC the powerwall also peaks at 7Kw and can work in an outage so my assumption is technically chadamo could also do it (personally ive never seen my smart meter go over 4.X Kw)

2) Some videos I have watches showed the chadamo charger being earthed as part of the installation - not sure if this is standard but I guess you could ensure thats done on installaton

3) safety is probably the key one - I know that it is very important to ensure that if you are running a generator during a power cut that you have to isolate yourself from the grid for the safety of anyone working on it - IIRC the powerwall does it automatically but I would assume a manual switch could be used?

My personal interest in this is driven by the storms over the winter - we had three power outages this winter, one of which lasted 4 days and meant we were essentially homeless for a couple of days due to the cold - I now have a petrol generator etc but it seems a shame not to be able to hook into the EV's ample batteries for a time
 

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Discussion Starter · #9 ·

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2) Some videos I have watches showed the chadamo charger being earthed as part of the installation - not sure if this is standard but I guess you could ensure thats done on installaton
The question is how? In grid tied mode, you can just use the PME earth, it’s when it goes stand-alone that it needs the right design. I suspect the installers for a trial wouldn’t go there and you’d find it simply permanently connected to the house earth.
3) safety is probably the key one - I know that it is very important to ensure that if you are running a generator during a power cut that you have to isolate yourself from the grid for the safety of anyone working on it - IIRC the powerwall does it automatically but I would assume a manual switch could be used?
You could use a manual switch but what you really want is to feed the circuits from the EPS output of the inverter so that they never go off. Trouble is that needs the house wiring to be modified so that different circuits are fed from different places and the protection needs to be designed so that it operates safely in off-grid mode whilst not limiting the load when there is more power available from the grid.


Unless you get the kit as part of a trial, V2X looks like quite bad value for money at the moment.

Whilst it’s a plus to have a big battery, the battery capacity is zero when the car is not at home. That means no battery to cover baseload and no battery to soak up free solar energy. Even when the car is at home, genuinely how big is the battery? Not much point in having a battery on wheels if it can’t be used as a car because you’ve burnt up the range powering the house.

I’d be all for V2X if it was similar in price to the inverter part of a static battery system (<£1,000) but at the moment you could get a decent sized static battery for the same money as an Indra and probably import less energy.
 
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