paulnmithompson
Posts: 1
Joined: Tue Aug 12, 2014 5:50 pm
Delivery Date: 12 Aug 2014

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

Tue Aug 12, 2014 5:59 pm

Older electric cars used DC, which required sophisticated and heavy relays to utilize regenerative braking. All modern EVs use AC as 1) the diodes are all there to recapture energy on brakingand 2) the motors are lighter and easier to control. AC also provides the ability to transform voltages with coils (transformers), not possible with DC. The present systems for PV electric are excellent, don't require storage batteries, and pay for themselves quickly (about 7 years), giving a return on investment of 9-14%.

WisJim
Posts: 38
Joined: Wed Jun 11, 2014 7:24 am
Delivery Date: 27 Jun 2014
Leaf Number: 409038
Location: Menomonie, WI

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

Tue Aug 19, 2014 11:12 am

Our previous electric car was a VW Golf converted to electric with a 120 volt battery. I have 5 PV panels arranged in series that I could plug directly into the car and charge it directly from the PVs as the output voltage of the panels fairly well matched the charging curve of the batteries--as the battery voltage increased, the current output of the PVs dropped significantly, down to an allowable trickle charge rate for the batteries. However, the microinverters on the other PVs that I have allow them to produce a higher wattage output because of the MPPT function of the inverters, and they are also giving e usable power whenever the sun is shining, not just when the car was plugged in, as the other inverters did. I came to the conclusion that it was more efficient overall to reconnect the 5 panels that had been used to charge the Golf, using microinverters, and have them feed into our home system also, and the end result, even considering inverter losses and charger losses, would overall be more efficient. Still need to find time to do that, though.

johnrhansen
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Joined: Mon Aug 12, 2013 7:23 pm
Delivery Date: 15 Jun 2013
Leaf Number: 409445
Location: Seattle, WA

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

Tue Aug 19, 2014 11:29 am

How would you regulate it? From what I've heard the leafs batteries can have anything between 300 and 400 volts on them depending on the state of charge. From what I know about charging batteries, most of the "resistance" of electrical flow comes from the voltage on the battery, not the resistance of the cells, so if you increase the voltage of the charger just a little bit, the current goes up a ton. (because you've already overcome the voltage on the battery, all that's left to slow down the current is the resistance of the cells, which is quite small) So no matter what you do you are going to need electronic switching on the charger end. So the only inverter you would save would be the one that converts the solar panel to ac. All kinds of people make those and like the previous posters have said, they have become quite efficient. Plus, I wouldn't want to trust my expensive battery to a charger I built with my limited resources and knowledge. Big corporations like Nissan have a sea of engineers working in a huge cubicle farm. surely they could come up with a better plan than I could in my cluttered garage.
2013 S model with quick charge package.
AV 30 amp level 2 EVSE, Bosch PowerMax 30 Amp EVSE, EVSE upgraded EVSE.

camasleaf
Posts: 610
Joined: Sun Sep 26, 2010 5:20 am
Delivery Date: 17 Jun 2011
Location: Camas, WA

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

Tue Aug 19, 2014 12:25 pm

Solar panels are a current source, their output voltage will change based on the load resistance. The current depends on the light input. At least that what I was reading about when I installed my PV system last year. The Leaf battery could directly take my 5.7kW output all the way to 90% SOC, but the people in the Nissan cubicles made sure I will not try that.
2011 SLe 06/17/11 Over 76000 miles 71%SOH 15.7kWh
2015 SV 09/02/14, Over 36000 miles soon to be returned for a 2018
5.7kW DC System

mctom987
Posts: 333
Joined: Wed Jun 25, 2014 6:52 pm
Delivery Date: 29 May 2014
Leaf Number: 332755
Location: San José

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

Tue Aug 19, 2014 3:07 pm

camasleaf wrote:Solar panels are a current source, their output voltage will change based on the load resistance. The current depends on the light input. At least that what I was reading about when I installed my PV system last year. The Leaf battery could directly take my 5.7kW output all the way to 90% SOC, but the people in the Nissan cubicles made sure I will not try that.

You'd need ~500Voc in order to attempt that, which shouldn't be too hard. Maybe 12 panels in series. You would also have to monitor the battery extremely closely, as you would have a significant chance of overcharging. Li batteries just don't have the overcharge tolerance of SLA.
2014 Green Leaf SL +PP
June: 580.6 mi, 4.7mi/kWh
July: 1443.8mi, 4.8mi/kWh
Aug: 1157.9mi, 5.1mi/kWh

jimbo69ny
Posts: 22
Joined: Tue Aug 12, 2014 2:23 pm
Delivery Date: 12 Aug 2014
Location: Ithaca, NY
Contact: Website

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

Tue Oct 14, 2014 5:16 am

Im pretty happy with my set up.
Image

Image
2014 Rav EV #3364
2012 Plug in Prius

OpenEVSE builds
priuschat.com/threads/my-openevse-build.115573/#post-1647089
Dual voltage, portable 40amp Openevse
myrav4ev.com/forum/viewtopic.php?f=9&t=1013&start=120

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dgpcolorado
Posts: 2966
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Delivery Date: 15 Dec 2011
Location: The Western Slope, Colorado

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

Tue Oct 14, 2014 5:27 pm

My 2170 watts of panels generated 103% of all the electricity I used to fuel my LEAF and power my house last year. Net metering is a lot simpler and safer than trying to fuss with regulating a DC charge to the car. Not that I could, since my LEAF doesn't have a DCFC port.
Blue 2012 SV Dec 2011 to Feb 2016
CPO 2014 Tesla S60 Mar 2016
One car, no ICE, at last!
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QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Bellevue (Seattle), WA

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

Tue Oct 14, 2014 5:41 pm

dgpcolorado wrote:My 2170 watts of panels generated 103% of all the electricity I used to fuel my LEAF and power my house last year. Net metering is a lot simpler and safer than trying to fuss with regulating a DC charge to the car. Not that I could, since my LEAF doesn't have a DCFC port.

How many miles do you drive? That is some serious conservation! You obviously have gas for space and water heating?

It takes a 17.9kW system (east/weast/south facing with lots of shade) to produce about 13.5 kWh annually for space/water heating, driving ~10k miles, and the rest of my electricity needs.

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
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Leaf Number: 2062
Location: Bellevue (Seattle), WA

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

Tue Oct 14, 2014 5:42 pm

jimbo69ny wrote:Im pretty happy with my set up.

How much more output do you expect to achieve based on that extra tilt? I presume the extra spacing help keep the wind loads limited significantly?

jimbo69ny
Posts: 22
Joined: Tue Aug 12, 2014 2:23 pm
Delivery Date: 12 Aug 2014
Location: Ithaca, NY
Contact: Website

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

Tue Oct 14, 2014 5:48 pm

Thanks to the idiotic company I used to install the pv system I am only going to be producing maybe 80 of what I use. Probably less actually. I used a local company called Solar Liberty in Ithaca NY and they were a bunch of idiots! I told him I was going to be soon heating a 690 sqft place using electric that was not heated previously and that I drove a PIP but I was going to be getting a fully electric car soon. He completely undersized my system and because it was through NYSERTA I am not able to modify or add to the system. I am Fing pissed! It only confirms to me that if you want it done right, you do it yourself.

The system is on a duplex that I also live in. There are two PV systems and the panels on the right are solar hot water. The PV systems are 3 kw and 5 kw I believe. The solar hot water is huge because it also contributes to heating the radiant floor.
2014 Rav EV #3364
2012 Plug in Prius

OpenEVSE builds
priuschat.com/threads/my-openevse-build.115573/#post-1647089
Dual voltage, portable 40amp Openevse
myrav4ev.com/forum/viewtopic.php?f=9&t=1013&start=120

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