pkulak
Posts: 758
Joined: Thu Sep 19, 2013 4:08 pm
Delivery Date: 18 Sep 2013
Location: Portland, OR

Just a question for you guys with panels and an EV...

Sat Jul 05, 2014 8:47 pm

Does it bother you that you're capturing power in DC, losing some of it through an expensive inverter, then loosing more again when your car's rectifier turns it right back into DC? Anyone ever think of just hooking some panels into a battery and using CHAdeMO exclusively to charge the car?

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Portland

Re: Just a question for you guys with panels and an EV...

Sat Jul 05, 2014 9:13 pm

pkulak wrote:Does it bother you that you're capturing power in DC, losing some of it through an expensive inverter, then loosing more again when your car's rectifier turns it right back into DC? Anyone ever think of just hooking some panels into a battery and using CHAdeMO exclusively to charge the car?
Not one bit. Let's pretend that this additional loss is 33% (that seems really high though). That means I could cut my 300kwh of charging to only 200kwh a month. So to save $120 a year I would need a seriously more complex system that would be very expensive as the most practical way would be to use a CHAdeMO converter that could take AC and DC at a varying levels based on a constantly changing solar PV output then there would also have to be a way for all the excess DC from the panels to inverted to AC. Then my state incentive is paid on AC production so that would not work well. I would have to replace my microinverters which are helping deal with my shade to central inverters. Lastly I charge in the early morning so the car is ready when I leave for work but there is no solar PV output at night.

I'm much happier generating more than 100% of my homes electricity usage including heating, cooling,
water heating and the LEAF. Using net metering I give the grid all my excess production and then when I need it the grid gives it back to me. This is extremely simple, doesn't require any special equipment, passes electrical inspection and is extremely cost effective.

arnolddeleon
Posts: 125
Joined: Wed Apr 21, 2010 3:58 pm
Delivery Date: 25 Jun 2011
Leaf Number: 4147
Location: Cupertino, CA

Re: Just a question for you guys with panels and an EV...

Sat Jul 05, 2014 10:34 pm

No. cf. QueenBee.

arnold

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Portland

Re: Just a question for you guys with panels and an EV...

Sat Jul 05, 2014 11:25 pm

arnolddeleon wrote:No. cf. QueenBee.
In case your Latij is rusty Arnold is saying No, refer to my reasons/ask me. I had to google to figure out cf. meant consult :)

User avatar
gbarry42
Posts: 888
Joined: Mon Jan 10, 2011 5:48 pm
Delivery Date: 06 May 2011
Location: Moonlight Beach

Re: Just a question for you guys with panels and an EV...

Sat Jul 05, 2014 11:58 pm

I suppose it bothers me more that for each 1,000 watts hitting the panels, you get 200 watts out. :)

Meanwhile, unless you can keep the DC output from your panels at exactly 394 volts, you are going to need something to adjust that voltage for you...something that looks an awful lot like another inverter ;)
___
Analogies greatly simplified in order to make a point without adding a lot of disclaimers or explanations
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

User avatar
Nekota
Posts: 616
Joined: Sat Dec 11, 2010 11:16 pm
Delivery Date: 12 May 2011
Leaf Number: 2182
Location: Sunnyvale, CA

Re: Just a question for you guys with panels and an EV...

Sun Jul 06, 2014 12:13 am

If just hooking some panels into a battery and then using CHADeMO to charge another battery were simple it would be done that way - the idea of DC to DC is appealing. But instead of efficiency at the local level consider efficiency at the grid system level. AC power is dynamic and generally peaks in the late afternoon and with a low demand in the early morning before sunrise. By contributing energy to the grid during high demand with solar PV and using AC energy to charge EV battery during low demand is actually helping the grid and the power company. As end use of electricity gets smarter and can turn itself on during low demand and off during high demand then more stability can be introduced into the AC power grid. Eventually, some feedback and control from the utility company or independent system operator (ISO) will also tell the PV system to produce less or more if the grid stability needs that. Currently the PV systems run at maximum output from the available solar flux so any type of grid control is likely years away. There is some degree of feedback operating now, each of the microinverters monitor the AC line and will not deliver power to the grid if the voltage is out of range or the AC frequency is out of range.
Res 20Apr2010 / Ordered 27Sep2010 / Delivered 12May2011

PV System

User avatar
RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Just a question for you guys with panels and an EV...

Sun Jul 06, 2014 2:22 am

pkulak wrote:Does it bother you that you're capturing power in DC, losing some of it through an expensive inverter, then loosing more again when your car's rectifier turns it right back into DC?
Not at all. In addition to what others have written, I will point out that the losses due to power conversion are already *very* low and will get lower in the future. The efficiency of microinverters is above 95% while the electrical efficiency of the LEAF's charger is also above 95%, so total electrical losses are less than 10%. In addition to the electrical losses, there is power wasted to run the cooling pumps. You could argue that this could be eliminated, but doesn't the LEAF run them during CHAdeMO anyway? (I wonder why?) Expect these efficiency numbers to get above 98% on both ends in the future, particularly for three-phase systems like they have in Europe. Small inverters at that efficiency level are already being deployed in three-phase PV generation systems.
pkulak wrote:Anyone ever think of just hooking some panels into a battery and using CHAdeMO exclusively to charge the car?
As QueenBee said, that would be a one-trick pony. Also, 240VAC is quite a bit safer than 400VDC.
Nekota wrote:But instead of efficiency at the local level consider efficiency at the grid system level. AC power is dynamic and generally peaks in the late afternoon and with a low demand in the early morning before sunrise. By contributing energy to the grid during high demand with solar PV and using AC energy to charge EV battery during low demand is actually helping the grid and the power company. As end use of electricity gets smarter and can turn itself on during low demand and off during high demand then more stability can be introduced into the AC power grid. Eventually, some feedback and control from the utility company or independent system operator (ISO) will also tell the PV system to produce less or more if the grid stability needs that. Currently the PV systems run at maximum output from the available solar flux so any type of grid control is likely years away. There is some degree of feedback operating now, each of the microinverters monitor the AC line and will not deliver power to the grid if the voltage is out of range or the AC frequency is out of range.
+1, and I would take this a bit farther: The best case is to never curtail renewable generation. If the on-board chargers in EVs can be replaced by four-quadrant power converters that can act as either a charger OR a generator, then we can have our EVs provide electricity to the grid during peak demand periods. As more and more PV and wind generation and more and more EV storage is added to the grid, we should eventually be able to curtail the more polluting generation systems rather than curtailing the PV.

Finally, I will point out that the motors used in the mass-produced EVs in the world are AC motors. Perhaps we should be using DC motors to eliminate a conversion there! ;)
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Portland

Re: Just a question for you guys with panels and an EV...

Sun Jul 06, 2014 10:33 am

RegGuheert wrote: Finally, I will point out that the motors used in the mass-produced EVs in the world are AC motors. Perhaps we should be using DC motors to eliminate a conversion there! ;)
Or AC batteries!

User avatar
RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Just a question for you guys with panels and an EV...

Sun Jul 06, 2014 1:04 pm

QueenBee wrote:Or AC batteries!
I thought about typing that. But then I thought "Nah, too corny!" (Even for me!)

But apparently not for QueenBee!! :lol: :lol:
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Portland

Re: Just a question for you guys with panels and an EV...

Sun Jul 06, 2014 2:14 pm

RegGuheert wrote:
QueenBee wrote:Or AC batteries!
I thought about typing that. But then I thought "Nah, too corny!" (Even for me!)

But apparently not for QueenBee!! :lol: :lol:
It's a solution that kills both the motor's AC/DC inverter and the on board charger's ;)

Return to “Solar”