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So I'll try to ask the question without turning this into a rant.

I'm looking at putting solar panels on the roof of m house at some point in the future. I know for larger installations it's best to get a battery storage and I'm thinking about the whole Vehicle to Grid (or rather Vehicle to Home) setup as being a good way to boost any battery capacity.

Now the ideal solution in my view would be to charge using DC instead of AC. That way you could hook the EV directly into the DC network from the solar panels and bypass the inverter. This means you avoid the conversion loss from converting DC to AC then back to DC again. This conversion loss is pretty significant (~24% of the panels output power would be lost to this) and I think would make it possible to also power the house using an EV (CCS and Chademo both support V2G and you already have an inverter for the solar panels)

Unfortunately, I haven't been able to find any system which does this. I suspect no-one has built one yet but was wondering if anyone else has come across some sort of DC home charger?

NOTE: Just to be clear, I'm talking about slow (3-7kW) charging here, not the 50kW+ rapid DC chargers. I'd have to put panels on all my neighbours houses to get anywhere close to that much power, and I imagine they'd object! :D
 

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Now the ideal solution in my view would be to charge using DC instead of AC. That way you could hook the EV directly into the DC network from the solar panels and bypass the inverter. This means you avoid the conversion loss from converting DC to AC then back to DC again. This conversion loss is pretty significant (~24% of the panels output power would be lost to this) and I think would make it possible to also power the house using an EV (CCS and Chademo both support V2G and you already have an inverter for the solar panels)
That would only eliminate ONE of the two power conversion steps: instead of DC->AC and AC->DC you would just have DC->DC. So definitely an improvement, but not as big as you state.
 

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To use DC it's the same CCS or Chademo port as the type 1 or 2 is ac. But you do not need 50kW or even 20kW as I understand it, think of a rapid tapering off.
However you do need the rapids control electronics to talk to the car and do the dc charging. This is the missing link :(
BTW the chademo plug and the CCS one are not cheap.
 

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Well, the inverter in your house has already converted it to AC. So there’s that.

Then the charger will need to convert to AC to change the voltage on any case.

Do you really think you’re missing out on electrons?
 

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That would only eliminate ONE of the two power conversion steps: instead of DC->AC and AC->DC you would just have DC->DC. So definitely an improvement, but not as big as you state.
True, but DC to DC conversion should have an efficiency around 95% whereas AC to DC conversion only has an efficiency around 80%, so while it isn't lossless, it's cutting out the worst performing step
 

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AFAIK, the only way to DC charge a Leaf is via Chademo, i.e. rapid charging, like the OVO system:



Meanwhile just a reminder that you only have about 6 months to install your panels if you want FIT payments.
 

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Well, the inverter in your house has already converted it to AC. So there’s that.

Then the charger will need to convert to AC to change the voltage on any case.

Do you really think you’re missing out on electrons?
With solar in Irish climate, you really need to make every electron count.

Ultimately the car's battery is charged using DC. When you plug in an AC charger the car converts it to DC. When you connect to a DC charger the car just skips the conversion step.

Solar panels output DC, which is converted to AC to power the house electrics. All these conversions cause a loss.

What I'm proposing is to cut out the conversion between the panels and the car as much as possible by keeping it all DC, and hopefully maximising efficiency.
 

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With solar in Irish climate, you really need to make every electron count.
If you're in Eire ignore my comment about FIT - it only runs out in the UK. Eire has just started its own version, that also gives you money off batteries.
 

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DC charging is at around 300+V, are you aiming to get your solar panels up to that voltage? Simply there is no standard for low power high voltage DC charging, so just stick with established structures of converting to A.C. and then standard A.C. chargers.
 

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Surely anyway it would stop charging as soon as the sun goes behind a cloud (I don't know how well Chademo charging copes with that) - unless you have a battery, and those are mostly AC-connected these days because of the FIT benefit.
 
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If you're in Eire ignore my comment about FIT - it only runs out in the UK. Eire has just started its own version, that also gives you money off batteries.
Yeah unfortunately not FIT in Ireland. The grant for PV systems looks good but for some reason they only applied it to houses built before 2011, something about newer houses (like mine) being built to a more energy efficient standard
 

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AFAIK, the only way to DC charge a Leaf is via Chademo, i.e. rapid charging, like the OVO system:



Meanwhile just a reminder that you only have about 6 months to install your panels if you want FIT payments.
Worth being aware that the ac to dc conversion still happens in the wallbox, it is only skipped in the car - efficiency is more or less the same.

It is on our roadmap to add the ability to charge direct from solar (dc-dc) but this is some time away.

Sent from my SM-N950F using Tapatalk
 

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It is on our roadmap to add the ability to charge direct from solar (dc-dc) but this is some time away
Presumably this could be incorporated into the CHAdeMO V2G kit you make? Maybe with battery storage?
 
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What is needed is solar to static dc battery which is charged up during the day, then (semi-Rapid) transfer from static dc battery to car dc battery for a fast top-up before going out in the evening [or, if the car is not needed in the evening and there is a decent evening peak export price, export from static (and possibly car battery) to the grid with later cheap off-peak overnight charging of car battery from the grid]. For V (and static battery) to G to work, there needs to be dynamically flexible time of day pricing for both import and export of power to the grid.
 

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It might be possible to connect DC solar direct to the car?
Many psu can be plugged into high voltage dc or ac. It doesn't matter as it all gets bridge rectified in the psu. Has anyone stripped a car charger to see if there are bridge rectifiers next to the ac input?
 

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So I'll try to ask the question without turning this into a rant.

I'm looking at putting solar panels on the roof of m house at some point in the future. I know for larger installations it's best to get a battery storage and I'm thinking about the whole Vehicle to Grid (or rather Vehicle to Home) setup as being a good way to boost any battery capacity.

Now the ideal solution in my view would be to charge using DC instead of AC. That way you could hook the EV directly into the DC network from the solar panels and bypass the inverter. This means you avoid the conversion loss from converting DC to AC then back to DC again. This conversion loss is pretty significant (~24% of the panels output power would be lost to this) and I think would make it possible to also power the house using an EV (CCS and Chademo both support V2G and you already have an inverter for the solar panels)

Unfortunately, I haven't been able to find any system which does this. I suspect no-one has built one yet but was wondering if anyone else has come across some sort of DC home charger?

NOTE: Just to be clear, I'm talking about slow (3-7kW) charging here, not the 50kW+ rapid DC chargers. I'd have to put panels on all my neighbours houses to get anywhere close to that much power, and I imagine they'd object! :D
I have said several times before that I think DC charging of EVs (delete the on board charger, delete mass, delete cost) is the way forward. Seriously, how often do you either charge away from home or not on rapids? OK, I know some people like sucking up free electrons from destination chargers, but it is pretty desperate IMHO, either because you have to suffer such a long wait on a journey that actually calls for rapid charging, or you didn't really need to charge at all.

Unfortunately, few seem to have yet shared our vision, so the problem is less to do with finding a DC-DC converter with the right voltage specifications, the issue is getting that DC into the car, because low power connections via the rapid ports isn't something yet marketed.

But keep thinking the problem through and one day someone, possibly you or less likely I, will make that happen and everyone will begin to understand why they should have their own DC EV supply in their garage.
 

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I have said several times before that I think DC charging of EVs (delete the on board charger, delete mass, delete cost) is the way forward. Seriously, how often do you either charge away from home or not on rapids? OK, I know some people like sucking up free electrons from destination chargers, but it is pretty desperate IMHO, either because you have to suffer such a long wait on a journey that actually calls for rapid charging, or you didn't really need to charge at all.

Unfortunately, few seem to have yet shared our vision, so the problem is less to do with finding a DC-DC converter with the right voltage specifications, the issue is getting that DC into the car, because low power connections via the rapid ports isn't something yet marketed.

But keep thinking the problem through and one day someone, possibly you or less likely I, will make that happen and everyone will begin to understand why they should have their own DC EV supply in their garage.
I think we were chatting about this some time ago and I was defending the AC side of things. Unfortunately you've planted the seed of thinking in my head and now I'm searching everywhere for DC chargers.

To be fair, I can see the appeal of AC chargers since they're much easier to install and are smaller and less complex, resulting in a cheaper charger.

However, I would really like to see more generations of home DC chargers available which can be fed directly from solar panels (via a DC-DC converter) and top up from AC mains when sun isn't shining. Ideally it could also reverse feed back to the house, powering the house or charging a stationary battery bank, or feeding the grid depending on which is more advantageous.

I agree that AC charging adds bulk and cost to an EV, unfortunately I think it'll take a long time for the infrastructure to evolve to the point they can be removed completely. Maybe they'll be downgraded at some point to an external granny lead with a rectifier onboard, to give you the option of charging from a wall plug if you're desperate.

I have seen one or two home DC chargers available, however the all fed from AC mains and cost in the region of €5000 upwards. So in the near term I don't think there's anything that suits my purposes out there.
 

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Cruisey1987, Bimble Solar have what you are looking for, direct DC charging from your panels via ChaDemo plug and CAN controller. Be warned, it's eyewaterinly expensive.
 

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Cruisey1987, Bimble Solar have what you are looking for, direct DC charging from your panels via ChaDemo plug and CAN controller. Be warned, it's eyewaterinly expensive.
Nice spot freddym, thanks for posting that.

You're right, it's pretty expensive at £7000. And 45kW is a bit overpowered for my purposes. At the absolute max I could fit 12kW of panels on my roof, so I'd be hugely underloading the charger.

Hopefully they'll come out with a lower capacity and more affordable model at some point
 

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It might be possible to connect DC solar direct to the car?
Many psu can be plugged into high voltage dc or ac. It doesn't matter as it all gets bridge rectified in the psu. Has anyone stripped a car charger to see if there are bridge rectifiers next to the ac input?
It’s highly unlikely that any car chargers will accept DC on their AC input: any converter of this size is likely to be doing active power factor correction (ie. modulating the switching element such that the input current is a sinewave matching the input voltage). So you’d expect them to not run at all on a DC input.

If it’s a digitally controlled design, then possibly it could just be a software change to make it accept DC. However, there’s also the problem that contactors/breakers designed for AC don’t work on DC (they don’t have the arc-breaking capacity), so it’s not something the manufacturers will want to support.
 
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