charging electric cars without an inverter

[wilburc]

Is anyone familiar with any systems that will let you charge an electric vehicle (i.e. Nissan leaf) directly from pv panels? Ideally this would involve just a charge controller which would eliminate the need to convert to AC and then back to DC again-

Will

[Naptown]

Although I am sure something could be engineered it may not be practical or cost effective.

[wilburc]

I'm not sure why you would you say it wouldn't be practical or cost effective- The approach I am interested would use less parts (no inverter) and should be more efficient b/c the energy wouldn't be converted to AC (causing a loss) and back to DC (causing another loss).

[Naptown]

But will the Leaf accept any thing other than an AC supply? I believe the charge control is onboard the car not within the charger. You also run the risk of voiding the waranty on the battery bank by doing so.

[wilburc]

Now those are 2 big issues- anyone else have any first-hand knowledge of charging with DC and voiding warranties?

[Sunking]

Wilbur it can be done but pretty foolish financially and enviromentally speaking. You will end up paying several multiples of what it cost just to buy from the POCO.

The Nissian Leaf battery has a 24 Kwh battery. Assuming you want to be able to charge it from 20% back up to 100% in a single day is going to require a 6 to 10 Kw system, and there will be a number of days you will not be able to charge due to cloud cover. That is a huge chunk of money at $15,000 to $25,000 for $2.50 of electricity per charge. You would be way ahead of the game installing a grid tied system that will utilize all the power the the panels can generate and not sit there doing nothing most of the time.

[billvon]

Is anyone familiar with any systems that will let you charge an electric vehicle (i.e. Nissan leaf) directly from pv panels?

It is quite possible. Some Leafs have a DC charge connector which allows direct battery charging intended for use with fast chargers. You have to be able to get to about 405 volts (at a reasonable power point) to charge the battery directly.

To get the car's contactors to close a lengthy CAN bus exchange needs to occur. So far I only know of two people implementing such a protocol, and both devices are over $10K. However 90% of that is in the AC to DC power electronics, which a direct solar system would not need.

Ideally this would involve just a charge controller which would eliminate the need to convert to AC and then back to DC again-

That's the positive. The negative in that arrangement is that the car has to be stationary at the panel during the day, which is when most people use them.

[wilburc]

I think this is progress...

Hello Billvon,
Thanks for your thoughts. I don't consider 405 volts to be a hurdle- stringing together 8 or 9 panels in series should supply that. Also, keeping the car stationary during the day is not a problem, I work at home!
I will look up the CAN bus exchange.
When you say you know of 2 people who are working on the necessary protocol, are these laypeople? companies? Would it be possible for me to get in touch with them?
Take care,

Will

[billvon]

When you say you know of 2 people who are working on the necessary protocol, are these laypeople? companies? Would it be possible for me to get in touch with them?

One is Nissan who recently announced a $9000 DC fast charger. The other is a company down here. I forget their name; I'll try to look it up. In the meantime, the 'My Nissan Leaf' forum is a great place for technical issues like that. Here's the CAN Bus forum:

http://www.mynissanleaf.com/viewforum.php?f=44

[bonaire]

I've got a Volt and wouldn't do that. Grid-tie Solar PV is really the only way to go. You first don't have typical DC charging stations at all on the market yet. Then, when they do come out, they will push big amperage for "fast charging". You could supply the potential (Volts) but not the Amps to do their future designation of fast charging. Volts arent energy and 8-9 panels really don't allow for high Amperage enough to charge a car. 8 250W panels are only 2KW. 220V is only 9A at that potential and that is at MPP which is only noon-time. The 220V charger for the leaf is 3.3KW and their next-gen fast charger is 6.6KW. You need 24 panels to get to the levels of real DC fast charging (if not way-more) and could only support the Amp draw during MPP hours and only during optimal sun conditions.

The industry standard is AC charging at 120V, 240V and Tesla has some other stuff. For the sub 1% who want to do direct Solar PV to EV, there will be very few solutions in the near-term (5-years).

For the OP - follow Sunking's advise and really just look away from the idea of direct DC charging off Solar. Mix Solar PV in with the normal residence utility power and that solves all issues. I also hear from people wanting to use Solar PV to charge a battery bank which then charges an EV. Another bad, poor financial decision and a lot of energy losses during all that charging/dumping.

[russ]

Grid tie is the only way to go - no question at all.

[Lendar]

Does anyone know how much time would it require to chage a car from 0% to 100% with solar energy. I think that everything under two days is acceptable.

[bonaire]

Charging an EV off "Solar Only", without being grid-tied, is not a viable or cost-concious option. More for the hobbiest or perhaps Gilligan's Island type scenario. Why not use the most appropriate use of Solar PV - grid tied?

Do you mean for a store-bought EV or some home-conversion EV?

[Sunking]

I agree using solar only to charge your EV is not only money foolish but a horrible idea environmentally. Defeats the whole purpose of an EV spending more than $1/Kwh and will never offset any emissions. You just as well sell it and get a gas or diesel auto.

But to answer your question to recharge in two days depends on your location and time of year. The Leaf has a 24 Kwh battery and assuming you could have a custom built Charger Controller and 4 Sun Hours per day for a total of 8 Sun Hours over two days would require a 6000 watt solar panel array.

[...]

[billvon]

Does anyone know how much time would it require to chage a car from 0% to 100% with solar energy. I think that everything under two days is acceptable.

With my system, DC to DC - 3.5 hours in full sun. AC in - 8 hours. (This time of year that means 6 hours one day and 2 hours the next.)