charging electric cars without an inverter

[russ]

Bill - I can not answer you in the manner you deserve - rules of the forum - but I have not often read such drivel.

[billvon]

I am not anti-progress now. I was when I was a left winger in college protesting nuke plants and sabotaging the Forrest industry. Bu tI put th eBong down and went to work for a living. I am all for development, just do not force me to where my money is going and let the Market decide where it goes.

The market is a great thing to apportion consumer goods and services to consumers, not so great when it comes to deciding national energy policy, public health, the survival of species, our foreign policy or requirements for fair competition. Leaving everything up to the market gave us Enron, Standard Oil, the Triangle Shirtwaist Company, the killer fogs in London, Donora, burning rivers in Cleveland etc. One of the things I learned _after_ college is that any extreme - pure capitalism, pure communism, pure socialism, pure democracy etc works about as well (i.e. not very well at all.) A wise plan does not worship any of those systems, and instead uses the best of each and rejects the worst of each.

You cannot stop or change the Market. It has always and will always make the decision.

How's Standard Oil doing these days?

I am an EV enthusiast and you know it.

Cool. People developing technologies and products for EV's and hybrids today stand to make a lot of money as improving technology drives wider adoption of those products. Primarily due to their marketability; hybrids are now standing on their own and selling in the millions. They got there partly due to help from governments (both Japan and the US) to get the technology over the barriers to entry. I think that's great - people have more choice nowadays, and with energy supplies getting tighter, choice is a good thing.

[billvon]

Bahwhahaha. You sure like spending others people money and wasting it. A good power pigtail cost a hundred dollars and electricity is dirt cheap. Spend $120,000 to make $2 worth of electricity per day for an EV . I know who you are voting for.

Your political rants are cute, but to the point -

My company has installed about 400kW of solar. We do a lot more with it than "making $2 worth of electricity." One of the things we do with it is convert the 500VDC to 480 volts AC via GT inverters, convert that to 240 volts via a local transformer, then convert it back to 400 volts DC to charge all the EV's we have. (We're planning to support around 100; right now we're at 21 charging stations, which supports about 60 cars total.) That's around a megawatt-hour of power a day that goes through all those conversion steps. Being generous and assuming a 90% conversion at each stage (95% for the transformer) that's 250 kilowatt-hours of power wasted every day, or about $9000 a year wasted.

[...]

[Sunking]

[...] A good power pigtail cost a hundred dollars and electricity is dirt cheap. Spend $120,000 to make $2 worth of electricity per day for an EV [...]

[billvon]

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

Another thought on how you could approach this:

Install a commercial (say 40kW) system at a local shopping center. Wire it in strings such that Vmpp is around 450 volts and you end up with 8 5kW strings. (This is a common target voltage.) Wire all of them to a commercial 40kW grid tie inverter (or bank of inverters, whatever's cheaper.)

When anyone plugs a car in, then one of those strings is switched from the inverter to a DC/DC that drops the voltage from 450ish volts to the 403 volts that the Leaf needs. A DC/DC converter designed to run at 90% duty cycle is relatively cheap and easy to design. While the car is plugged in, that string is dedicated to that car. When it is removed, the string is returned to grid tie operation.

[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.)

[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.

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[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?

[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.

[russ]

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

[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.

[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

[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]

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.

[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.