EV charging, AC vs DC (over a distance)

[Ihavenojob]

If (and it's a BIG if) I get an EV, is charging it via DC direct from solar quicker than AC from solar with an inverter? The charging port will be about 30 metres from the house, so would running DC that distance have any benefit over using an inverter and AC, or will the DC lose power over that distance? Is it six of one, half a dozen of the other, or is there a definite winner?

 

[flameport]

I get an EV, is charging it via DC direct from solar quicker than AC from solar with an inverter?

Irrelevant, as you won't be charging an EV 'direct with DC'.
They all require 230V AC.

The only DC charge options for EVs are high powered dedicated charging devices as found at motorway services and the like, and even they require AC as the input, typically a 3 phase supply capable of at least 100kVA, and the units themselves cost upwards of £25k each for cheapo models.

 

[plugwash]

You can't charge an EV "direct" from solar panels.

In general, there are a few ways of charging EVs.

Single phase AC, generally supports up to 7kW with UK spec EVs. The simplest soloution and usually enough to charge most EVs overnight. The "charger" which converts the fixed incoming voltage to the charge voltage/current needed by the battery pack is inside the vehicle, with the chargepoint just being a switching/safety device.

Three phase AC, can support up to 21kW on some vehicles, but relatively few go this high. Again the charge management. The "charger" which converts the fixed incoming voltage to the charge voltage/current is inside the vehicle. Generally you will need a 3 phase grid connection if you want to go this route.

DC rapid. The charge point is now an actual charger, converting the incoming power to what is needed to charge the battery. Much higher speeds are possible but the equipment is expensive and provisioning a suitable electricity supply can also be a challenge.

There is at least one manufacturer, sigenergy, that offers 12KW and 25KW DC rapid charging modules for their home solar/battery system. The 25KW module is about £2K but that is of-course on top of buying the rest of their solar/battery system. If you use such a module it will also mean that your battery stack has to be located next to where you plan to charge your EV.

 

[ericmark]

The problem is in the main, people buy a car which needs more than 35 kWh to charge it. Simple maths 5 hours x 7 kW = 35 kWh.

The way to extend it is home batteries, or a car which can take excess solar, I don't know of any, but the iboost+ does it with an immersion heater, so there is no technical reason it can't be done with a car.

But static batteries have other benefits, so they seem to be what most select. However, inverters produce heat, mine is in the flat, which used to be the coolest place in the house in summer, not any more, it has really messed up my beer brewing, it's now too hot.

Yes the heat is wasted energy, but you can't get around using inverters, the car uses too high a voltage DC for it to charge direct, so no real option.

 

[Ihavenojob]

This was from one site I looked at. I had previously thought people were using solar direct to car.

How Solar-Powered EV Charging Works​

The concept is straightforward: your solar panels generate DC electricity during daylight hours. An inverter converts this to AC electricity that your home uses immediately or stores in a battery. When you plug in your EV charger, it draws this solar-generated electricity directly to charge your vehicle.

The beauty is simplicity. You need three components working together:

• Solar panels: Generate the electricity
• Inverter: Convert DC power to usable AC electricity
• EV charger: Convert AC electricity to the DC current your vehicle's battery requires

I wouldn't call that simple, when you convert DC to AC, then back to DC. Someone should invent something to smooth out the DC so you have panels and car charger. Oh well, stick with the diesel.

 

[ericmark]

DC to DC or DC to AC it still needs an inverter.

The inverter allows the panels to reach the best voltage to produce power this will vary through the day, so it needs that inverter. Early solar panels, would not produce anything until it reached battery voltage, and after that point their output was reduced, the MPPT inverter even with 12 volt versions got around that problem, and vastly increased the solar panel output.

But even without adding an EV, the solar panels need a battery, and inverter to keep the grid use during peak times to export only.

This is why the plug and play system seems a bit daft, the first dip is when battery recharged with off-peak, the second where we made coffee. Once off-peak has ended the battery ensures we don't use grid power. The solar and battery work together, it needs both, but my inverter is only 5 kW so it would be too small to work with an EV. My 6 kW panels can during this heat wave, produce around 33 to 38 kWh per day, so with an EV likely you would want a lot more.

The critical time is the evening, solar this time of year will stop producing enough for my needs around 7 pm and I don't get off-peak until 00:30 am, so 5.5 hours running on battery. 5:30 to 9:30 only 4 hours, and very little being used. We start getting solar at 5 am and finish at 9 pm this time of year, but the amount 5 am to 9:30 am or 7 pm to 9 pm is very little.

 

[flameport]

The problem is in the main, people buy a car which needs more than 35 kWh to charge it. Simple maths 5 hours x 7 kW = 35 kWh.

This is not a problem, as no one arrives home every day with 1% remaining and then has to charge to 100% every night ready for the next day of driving to the absolute maximum range of the vehicle.
Just as no one fills their car with petrol or diesel from nothing to overflowing every day.

On the rare occasions they might need to charge for more than 5 hours overnight, then they just do so. A few of those hours will be more expensive, but still vastly cheaper than some diesel or petrol equivalent.

 

[flameport]

Someone should invent something to smooth out the DC so you have panels and car charger.

To charge a battery from solar panels requires that the voltage from those panels is adapted to suit the battery.
In the case of an EV, that battery is either around 400 volts or 800 volts, so you would need to convert the varying output voltage from whatever solar panels you have got to whatever the vehicle requires.
As a battery charges, the voltage and current required to continue charging will change. The output from solar panels changes continually due to the time of day, cloud cover, shading from trees, leaves, birds crapping on them and so on.
In every case, a big box of electronics will be required.

I wouldn't call that simple

It's very simple. Solar panels and the EVSE are installed.

After that, you plug the EV into the device on the wall. That is all.

Oh well, stick with the diesel.

If you want to continue burning money, then good luck with that.

 

[ericmark]

This is not a problem, as no one arrives home every day with 1% remaining and then has to charge to 100% every night ready for the next day of driving to the absolute maximum range of the vehicle.

This is my problem, I often deplete the battery in my e-bike so only way home is peddling, and the battery takes around twice as long to charge, as it does to discharge.

Since we hear again and again discussions about range, it makes sense to think this is a problem. So a small EV say Fiat Panda has a 44 kWh battery, it says 198.9-mile range, so 35 kWh will take it 158 miles.

To the question, how many miles will a full tank of diesel last?
AI Overview
A full tank of diesel typically lasts between 400 and 700 miles for a standard passenger car. However, the exact range varies widely based on your vehicle's tank size and fuel efficiency.

So trip to hospital 42 miles each way, so 85 miles just to visit hospital, to go 80 miles away from home, is not really that far, the only saving grace is your starting with a full tank.

As we move to larger cars Range Rover Electric: Features a 118 kWh battery pack with a diesel larger cars have larger tanks, but with an EV, it does not matter how much the battery will hold, limited to 35 kWh overnight charge. So that 300-mile range, equals 89 miles per day.

And unlike my e-bike, you can't pedal it home.

 

[flameport]

, it does not matter how much the battery will hold, limited to 35 kWh overnight charge.

Anyone can plug in an EV to charge at any time and leave it charging for as many hours as they want.
There is no limit or restriction.

 

[ericmark]

8.625p/kWh v 32.277p/kWh is a massive increase, OK not as much as paying at a public charging outlet, where you also pay more VAT, however, it does seem to be a repeat of the solar panel where to start with the government did loads to promote them, but then they removed many of the incentives, and they are nowhere near as good as a deal to when they first arrived.

The electric prices change area to area, and company to company, with some off-peak deals being only 3 hours, and some 10 hours. The thread starts off with links to solar, and I found the tariffs offered are really complex, with some being 3 stage for the import, and the rates over last year for the tariff I have has changed twice in the last 6 months, which is OK for solar, but for an EV the tariff is pivotal, for solar, I am still making with a simple tariff, with an EV, one is very dependent on the tariff.

 

[denso13]

however, it does seem to be a repeat of the solar panel where to start with the government did loads to promote them, but then they removed many of the incentives, and they are nowhere near as good as a deal to when they first arrived.

Just a natural progression as take up increases, like most things. It would be unaffordable to keep the initial incentives going for the long term. The uptake is still good so things can't be all bad.

 

[ericmark]

I have looked for a replacement small car, one narrow enough so I can get out of the doors in a car park, and with a two car family, having one electric is not really a problem, but this

is too slow, 28 MPH is going a bit silly, and the next size up goes silly, so would need to have sliding doors for me to get in and out, once we get wider. Looking for something like this

Japanese narrow cars, known as kei cars (or keijidōsha), are strictly regulated micro-vehicles defined by dimensions under 1.48 meters (4.8 feet) wide, 3.4 meters long, and 660cc engine caps. They provide maximum mobility on tight streets with lower taxes and great fuel economy.

and if the car is that small, it would not really need to be electric.