User avatar
johnr
Posts: 881
Joined: Sun May 02, 2010 2:08 pm
Delivery Date: 11 May 2011
Leaf Number: 2151
Location: Exeter, CA

Re: use of solar panel at spoiler on roof?

Thu May 27, 2010 9:43 pm

The solar panel spoiler serves a very important purpose: "Hey, look - I've got a solar panel on my car! Too bad your car doesn't, LOL"

If it powered a small fan to keep the interior of the car from getting too hot while parked in the sun, like the solar panel on the Prius, then that would be a very useful and practical feature.
My max efficiency: 200Wh/mi (5.0 mi/kWh)

First electric car to Mineral King? viewtopic.php?f=31&t=4952

Adapters for upgraded Nissan EVSE

mitch672
Posts: 1956
Joined: Fri Apr 23, 2010 2:10 pm
Location: Boston, MA

Re: use of solar panel at spoiler on roof?

Thu May 27, 2010 9:46 pm

On my Gen 2 Prius, their was a "resitive" heater than ran of the HV until the engine warmed up, on my Gen 3 Prius, they don't even have the restive heater any longer (engine waste heat only). The Air Conditioer does indeed run off the HV battery on the Prius, which is one of the reasons the engine starts more often (to recharge the HV battery at times)

I would fully expect the Leafs resistive heater, and Air Conditining compresser will run off the HV as well. Pretty much everything else I would expect to run off the 12V system.
2012 Advanced Plug in Prius (sold)
I Support OpenEVSE: http://code.google.com/p/open-evse/
My Fuelly page: http://www.fuelly.com/driver/mitch672/prius-plugin
Tesla Model S 85KW Dolphin Grey VIN: 03245, delivered 1/17/2013

AndyH
Posts: 6325
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: use of solar panel at spoiler on roof?

Thu May 27, 2010 9:48 pm

bradford wrote:how useful is the solar panel's charging? does it's 'trickle' help the main batteries, or is it somehow a boost for the accessories (like wipers, radio, heater...)?

thanks, Tom :?:


Here's a real world example of a small solar panel used to maintain a 12V battery during storage. This is what VW dealers use for cars sitting on the lot.
http://cgi.ebay.com/ebaymotors/VW-Solar-Panel-Charger-_W0QQcmdZViewItemQQhashZitem2a0746d902QQitemZ180510710018QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_500wt_1122

Max: 18.8V
Max: 170mA
Max: 3.2W

Andy

User avatar
garygid
Gold Member
Posts: 12392
Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
Leaf Number: 000855
Location: Laguna Hills, Orange Co, CA

Re: use of solar panel at spoiler on roof?

Thu May 27, 2010 10:16 pm

This 12v charger would need a cig. lighter or "power" port that is "always on".

Do modern cars have this?
I thought most were "switched" now.

What do the LEAF "ports" do?
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
To Sell: X-treme 5000Li EV motorcycle

AndyH
Posts: 6325
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: use of solar panel at spoiler on roof?

Thu May 27, 2010 10:21 pm

Dunno Gary. I've never seen one that' switched. I only presented the VW panel because it's roughly the size of the Leaf panel. Not a lot of power.

MikeBoxwell
Posts: 118
Joined: Mon May 24, 2010 4:25 am
Delivery Date: 26 Jun 2015
Location: Coventry, United Kingdom
Contact: Website

Re: use of solar panel at spoiler on roof?

Fri May 28, 2010 12:28 am

The panel is so small on the LEAF that it would maintain the 12v battery, but probably would not even charge it up. Assuming it is a 100Ah 12v battery pack and the car was parked up and not used, you could expect the pack to lose around 5-10% of its charge every month - so lets say that equates to around 90 watts.

A 6 watt panel (assuming that is what it is), flat on the roof of the car, would provide around 36 watt-hours of energy per day if the car was parked in sunlight, assuming it is a Californian summer, or around 4 watt-hours of energy per day if the car was parked in sunlight, assuming it is a British winter.

So in a Californian summer, it would take around one month to recharge your 12v battery pack from flat (assuming an 80% depth of discharge), whilst in the depths of winter in the United Kingdom, the solar panel would only just maintain the existing charge in the battery.

What you can do with 36 watt-hours per day of energy in a car (Californian summer)
There is some guesswork going on here, but this is what you can do with the 36 watt-hours of energy you can generate in a Californian summer with the built in panel:

Constantly run two small extractor fans inside the car to extract the heat from the cabin when the car is left unattended
Recharge a mobile phone, an iPod and a hand-held sat nav system all at the same time
Run the in-car sat nav system for 1½ hours
Switch on the headlights for around 15 minutes
Listen to the radio for around 45 minutes, or play a CD for around 25-30 minutes
Run the heating on max for around 50 seconds
Run the air conditioning on max for around 25 seconds

What you can do with 4 watt-hours per day of energy in a car (English winter)
Just about charge up a mobile phone if you leave it plugged in all day and don't use it
Half-charge a hand-held sat nav system (again, if you leave it plugged in all day and don't use it)
Run the heating on max for around 5.5 seconds


A few years back, my cigarette lighter packed up in my car. Because I relied on the cigarette lighter socket to power my hand-held sat nav system and I was in a hurry, I quickly rigged up a 12 watt solar panel I had lying around with a car cigarette lighter adaptor that I also had lying around, and put it on the rear parcel shelf. It worked a treat for keeping my mobile phone and sat nav running.

User avatar
planet4ever
Posts: 4674
Joined: Sat Apr 03, 2010 9:53 pm
Delivery Date: 02 May 2011
Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: use of solar panel at spoiler on roof?

Fri May 28, 2010 3:50 am

Since the OP asked about charging the "main batteries", you should have added one other item to your excellent list:

California summer: Drive the car 25 yards or so.
English winter: Drive the car 2 or 3 meters.
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

MikeBoxwell
Posts: 118
Joined: Mon May 24, 2010 4:25 am
Delivery Date: 26 Jun 2015
Location: Coventry, United Kingdom
Contact: Website

Re: use of solar panel at spoiler on roof?

Fri May 28, 2010 5:19 am

planet4ever wrote:Since the OP asked about charging the "main batteries", you should have added one other item to your excellent list:

California summer: Drive the car 25 yards or so.
English winter: Drive the car 2 or 3 meters.



:lol:

OK. I've worked it out - 665 feet and 3 inches for a Californian summer, 73 feet and 10 inches for an English winter (assuming 5 miles per kWh and 30% system losses).

User avatar
garygid
Gold Member
Posts: 12392
Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
Leaf Number: 000855
Location: Laguna Hills, Orange Co, CA

Re: use of solar panel at spoiler on roof?

Fri May 28, 2010 6:09 am

In older cars the cig. lighter was always ON, connected through a fuse to the battery.

In newer cars, the cig. lighter (and / or "power port") are not powered when the car is turned off, so it would seem that they go through a relay in addition to the fuse.

For example, a "handheld" GPS, plugged into one of these "switched" 12v "power ports", will ... lose external power when the car is switched off.

Since they are not "connected" to the battery when the car is OFF, they will not work for maintaining the 12v battery charge level.

Also, in the EV, do not expect a heavy 100-amp 12v battery. More likely it will be a much lighter, smaller battery, something like 20 to 30 amp-hours (240 to 360 Wh).

Typically, immediately after driving the car, this EV 12v battery will be "full", but have a very small "load", to keep the RFID-detection electronics alive, if nothing else.
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
To Sell: X-treme 5000Li EV motorcycle

User avatar
Nubo
Posts: 4220
Joined: Fri May 28, 2010 11:01 am
Delivery Date: 31 Oct 2014
Location: Vallejo, CA

Re: use of solar panel at spoiler on roof?

Fri May 28, 2010 11:12 am

garygid wrote:... Note: If one arrives at work with a fully-charged 12v battery (which would be the usual case), parking in the sun for 8 hours will be of little (or no) benefit.


I would suspect that the battery management system would leave some amount of "headroom" on the service battery. For example, say they set a target where the system attempts to keep the service battery at 70% charged at all times. This would provide a "reservoir" to let you get some benefit from the panel. Whatever extra you manage to feed to the service battery equates to a period of driving where the traction pack is not called upon to "feed" the service battery.

That said, yes it's a small amount. Over the course of a year it probably wouldn't amount to a day's driving. Over the life of the car it might just pay for itself. But it should start good conversations. :)
I noticed you're still working with polymers.

Return to “News & Main LEAF Discussion”