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Posted: Wed, 11 Jan 2012, 16:33
I am thinking seriously about adding two solar panels to my EV. They will be:
1) A flexible solar panel on the front hood to recharge the auxillary battery in addition to the DC-DC converter. The set-up I am thinking about is a flexible solar panel about 40watts, hooked up to a regulator (maybe a Plasmatronics PL20) on the dash board with a connect/disconnect switch for the DC-DC converter so the panel can do the charging but I can switch back to the DC-DC converter if the sun is lacking. I may swap the existing starting battery for a deep cycle battery.
2) A 100 volt, 125 watt, solar panel on a roof rack to assist charging the main traction pack which is 96volt DC. This would also be controlled by a regulator on the dashboard.
I obviously welcome any and all comments, warnings etc about the above concept but also have some specific questions:
a) Does anyone know where I can get a 96volt regulator for the 100volt panel on the roof racks? I have searched the net and the highest I can find is regulators capable of handling 48volt systems?
b) I assume I should have the roof rack mounted panel set as low to the roof as possible to reduce my "frontal area" and thus my drag? Anyone have any comments about the aerodynamics of roof racks that I should know about?
As I said above all comments welcome (including laughter!)
Posted: Wed, 11 Jan 2012, 17:45
A few years ago, Plasmatronics told me they could do a 96 V version of one of their regulators as a special order.
Posted: Wed, 11 Jan 2012, 18:14
Is 96V your nominal pack voltage or voltage after a full charge?
Posted: Wed, 11 Jan 2012, 18:28
Paul - from searching back on your posts I assume that you are running 8 x 12V AGMs. At 13.8 Volts (a reasonable float voltage for AGMs) you would need 110 VDC - not 96 VDC. A 100 V PV may not put out enough voltage at any reasonable current to do the job. Do you have details on the Solar panel you intend to use. If you run more than 13.8 per battery then a PV regulator won't do because it will cook your batteries if you park in the sun when they are fully charged.
It sounds like you need a custom regulator. I wonder how much you would lose if you went for a lower voltage panel feeding a LowV to 240VAC interter feeding the on board charger(s). Just a thought.
Posted: Wed, 11 Jan 2012, 18:59
Do you actually have a source for the 100V panel? Because reaching 100V's means something near 166 cells in a panel!!!!!
Posted: Wed, 11 Jan 2012, 19:03
With the losses caused by the extra weight and lousy aerodynamics, you'd be much better off putting the solar panel on the roof of your house. You'd also be getting money for feeding it back into the grid during the day, then charging your car from cheap off-peak at night...
Posted: Wed, 11 Jan 2012, 19:13
Tritium_James wrote: With the losses caused by the extra weight and lousy aerodynamics, you'd be much better off putting the solar panel on the roof of your house. You'd also be getting money for feeding it back into the grid during the day, then charging your car from cheap off-peak at night...
I second that.
Posted: Wed, 11 Jan 2012, 19:45
Paul have you found a 100V 125W panel? I did a quick search and could not find anything like that.
You could use 4 30W 24V panels instead.
Over on Metrompg
he did a test on his Suzuki Swift with empty roof racks and saw a 12.7% increase in fuel consumption at 88kph.
125W of solar panels are only going to give you 3-4km of range after charging all day..
Posted: Wed, 11 Jan 2012, 20:02
NilCO2 said they no longer fit panels to their cars because of theft incidents and how little was gained from the input.
Posted: Wed, 11 Jan 2012, 20:03
I suggest you do some testing before you commit big bucks to solar panels.
Step 1 - the baseline.
Pick a reasonably long section of road.
While recording your power usage, drive along this road at a reasonably constant speed.
Repeat multiple times and average the results.
Step 2 - the test.
Attach your roof racks.
Build a mock up of the solar panels (eg wood frame, cardboard surface) and attach to the roof racks.
Repeat the procedure from Step 1 to get an average power usage with your extras attached.
Decide if the power you will lose additional wind resistance is worth the gain you will get (while driving and while parked) from the panels.
Posted: Wed, 11 Jan 2012, 20:19
Thanks everyone for the replies.
The 100volt panel is manufactured by Schuco International KG. Their BL 01 series of thin film panels range from 100watts to 130watts and are all 100volt. The rated voltage ranges from 105.0 volts for the 100 watter to 110.0 volts for the 130 watter. The rated current ranges from 0.96 amps to 1.18 amps. All are the same size 1300mm x 1100mm x 7.5mm thick and all weigh 26.4 kgs.
My vehicle is 96 volt nominal using 8 x 100 amp AGM batteries.
I went to golf day before yesterday and used 8 amp hours to get there. The vehicle sat in the sun for 5 hours being 3 & 1/2 hours on course and 1 & 1/2 hours in the club house. At a 1.14 amp rated current for the 125 watts model I would have "got back" three quarters of my energy expenditure used getting to the course.
I realise the weight of 26.4 kgs will increase the weight of the vehicle by 2.87% but the spare tyre I started carrying recently appears to make no difference to my economy and it weighs about 20kgs.
I already charge off-peak using green power as the car is on a timer.
I could position the roof racks slightly higher at the front than the back thereby causing "lift" with a resultant decrease in rolling resistance improving economy!!
Also I could add a reverse spoiler giving me even more lift!
Above 70kmhr I would leave the ground?
But seriously do roof racks add much to drag - even the aerodynamic spoilers that are available now?
Posted: Wed, 11 Jan 2012, 20:57
You'll only get the 125W if it's perfectly sunny with the panel directly pointed at it and probably positioned close to the equator.
So would be more like 100W.
My wife says I should loose the spare tire too
Posted: Wed, 11 Jan 2012, 21:09
Richo wrote:My wife says I should loose the spare tire too
...and stop speaking North American.
Posted: Wed, 11 Jan 2012, 21:59
Remember, depending on where you leave the ground, there may be parking fees
Posted: Wed, 11 Jan 2012, 23:10
Maybe if I lost the spare tyre I could use it to break my fall when I land?
Posted: Thu, 12 Jan 2012, 20:22
Johny wrote: ...and stop speaking North American.
Oh golly gosh ::Wobbles head::
I blame the keyboard
It might be worth while if it was a bus and the panels were integrated into the roof.
Posted: Thu, 12 Jan 2012, 20:36
A few years ago I read a couple of Sci Fi teens books (my daughter was reading them) about Uglies and Pretties and stuff. In the book the author had them riding hoverboards that were charged by rolling out a large "sunmat" for a few hours. Basically a flexible solar panel array.
The only way I can see this kind of solar charging working is, as Richo says, in a big flat roofed vehicle - or a seperate panel that can either cover the vehicle like a car cover (reasonably theft proof because it's not too obvious - but not efficient), or sit beside it on a flat piece of grass if parking allows (it does for me at work) - but a thief magnet.
Flexible panels attached to a high-end car cover would be the go me thinks. Pain in the bum to deploy and fold away though. How long would it last treated like that?
Posted: Thu, 12 Jan 2012, 20:48
Or integrate cells into the body panels, ie: make the bonnet and roof out of fibreglass and embed solar cells.
Posted: Fri, 13 Jan 2012, 14:17
I had thought of the "theft" issue and will be discussing ways of reducing that risk with the people who I am getting to fit the panels. The solar shop, from whom I have been purchasing panels, inverters and regulators for the last ten years, specialise in fitting out campervans and motorhomes and will have little trouble wiring things up for me.
If people really want to steal something they will find a way but I am hoping to discourage people who just happen by the car in a shopping centre carpark!
Posted: Sat, 14 Jan 2012, 00:03
http://www.toyota.com.au/prius/gallery/ ... ion-system
I like the concept of the Prius solar roof.
But when it's 38 deg outside it's goting to be 38deg inside.
More for novelty rather than functionality.
http://www.pcworld.idg.com.au/article/4 ... ar_panels/
Or do the windows.
Green tint is so cool
I remember there is red see through solar panels as well.
Red tint is so cool
Posted: Sat, 14 Jan 2012, 03:25
I was thinking about getting a rotating windmill vent thingy for a house and a friend said that they were very effective because of how air in the top of a room just sits there and gets hotter through the day but if you can release it through the ceiling via one of the whirlybirds (yes, I think that's it), it makes the room much cooler overall.
I guess that is what the Prius device would achieve. It would still be quite warm on arrival but wouldn't, as is often the case in summer, give the impression that you have minutes before you'll suffer the closed car rapid death.