Solar charged EV

3656 Views 19 Replies 9 Participants Last post by rfhendrix, Feb 5, 2011

rfhendrix

Discussion Starter · Jan 27, 2011

Hi. I am going to build a Ford Ranger conversion tentatively with a 144 volt system using 12 12volt batteries and a motor and controller to be determined. I have mechanical and electrical skills and I am continuing to study before I do the conversion but I have a few questions I haven't been able to find an answer for.

I have about 40 square feet of space for solar panels on the rack and since my commute is only 5 miles a day, 4 days a week I think that the solar panels will keep it charged, especially since I live in southern California. For long trips only I am thinking about carrying a standard portable gas generator in the bed and operating the truck as a kind of hybrid until I get to my destination where I can recharge with the plug. I really do not need to go over 160 miles in any case.

Is the idea practical? I mean without too much complication. Has anyone here done something similar? If you have I would certainly appreciate the benefit of your experience, or any ideas from anyone here.

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dimitri

· #2 · Jan 27, 2011

Its theoretically possible, but not practical at all. You need to learn to operate in same energy units, so you can see why its not practical. Use Watts and Watt/Hours instead of square feet. How many Watt/Hours does your panel produce in reasonable time and how many Watt/Hours does the car use to travel reasonable miles. When you compare these 2 numbers you will see why this idea is not practical.

icec0o1

· #3 · Jan 27, 2011 (Edited)

A 6x6 inches solar cell that you can buy on ebay makes 0.55V and 8 apms = 4.4 watts. At 4 per square foot, you can get 160 of these cells on your roof = 704 watts an hour. For a truck, I think you'd need about 300-500 watt hours per mile depending on your driving style, speed, and aerodynamics. Of course those 704 watts are calculated with the sun being directly overhead (on the equator at noon) while not allowing the cells to heat up, because they lose efficiency as they get hotter. I'd venture a guess that in California, during the summer, calculating for about 6 hours of fairly strong sunlight per day, you'd get about 200-250 watts an hour since your array wont be tilted towards the south for a total of 1.2-1.5 kw hours. That'd be enough for about 4-5 miles. If you have a pack that could store a few more KWhours enough for 10 more miles of charging during the weeked, I suppose it could work. Of course, a few clowdy/rainy days will force you to have to charge it from an outlet.

You can get those 160 photovoltaic cells for something like $350 so it might be worth it finantially, although I'd only do it for aesthetics/cool factor. I do like the blue reflective look of those cells

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Bottomfeeder

· #4 · Jan 27, 2011

Cost and complexity will rear their ugly heads. Many, many people have discussed solar power EV conversions. Very few get built, and the ones that do get built don't get bragged about.

Do your conversion first, and then start thinking about ideas like solar and genset hybrids. You may find that you don't need them once you're on the road!

rfhendrix

Discussion Starter · #5 · Jan 27, 2011

Thanks for the advice. And thanks for all the input so far. I'll check back later today on this thread. I will definitely take the advice to build the conversion first and do the solar thing later. What I want is basically solar trickle charging during the time the truck is sitting which is most of the time.

Bottomfeeder

· #6 · Jan 27, 2011

In general, the conclusions people reach is that it's more effective to use a stationary, properly aimed solar system. Pump the power into your grid, so it doesn't sit idle if you're not charging. And charge your EV off the grid. But then your solar panels are really completely independent of your EV. But, that will make both projects more manageable.

If you want more range, it's much cheaper just to buy more/larger/better batteries.

Happy EVing!

Ziggythewiz

· #7 · Jan 27, 2011

icec0o1 said:
200-250 watts an hour since your array wont be tilted towards the south for a total of 1.2-1.5 kw hours.

Those are pretty harsh numbers. Rule of thumb is 4 hours*rating for average daily output (which accouts for indirect sunlight, etc).

=2.8 kWh

I'm planning something similar (mostly for show, but also to charge my ACC batt and hopefully contribute to the traction pack), but haven't gotten around to sourcing the materials to fit the very not flat roof of a bug.

Tahoe Tim

· #8 · Jan 27, 2011

From the calculations, it looks like you can recharge from you 5 mile commute during the day but you don't seem to have enough time after work to recharge before sunset.

As far as carrying a generator in the bed, there is a guy in Canada that does it successfully. You can look for his S10 in the garage.

rfhendrix

Discussion Starter · #9 · Jan 27, 2011

Tahoe Tim said:
From the calculations, it looks like you can recharge from you 5 mile commute during the day but you don't seem to have enough time after work to recharge before sunset...

Actually I work at night.

rfhendrix

Discussion Starter · #10 · Jan 28, 2011

I did a little figuring and measured my racks. I actually have more like 50 square feet of space for panels. I also have been investigating solar panels. Here is one idea of what is available:

http://www.amazon.com/New-Watts-Solar-Panel-Monocrystalline/dp/B002R1R6NE/ref=pd_sim_sbs_e_3

So I could put 4 of these 150 watt panels at $450 a piece and get 600 Wh. That would seem to be plenty, but at $1,800.00! Anyway, I know that costs are coming down for panels so I think the project is worth considering. By the time I finish the conversion who knows what might be available?

Feel free to correct my math or any of my hair brained ideas.

Roy Von Rogers

· #11 · Jan 28, 2011

The biggest problem with solar is payback. Even homes converted/supplemented with solar have a hard time getting a payback out of such investment. I'm not saying it cant be done, I'm saying you better consult with a professional before investing in such venture, and buying panels from amazon.com, aint gonna make it.

Think twice before starting something that will cost you and will not deliver a payback.

You better off using such funds for good TS or CALB cells, instead of 12v LA's. At least this way you get some bang for your buck.

Roy

Ziggythewiz

· #12 · Jan 28, 2011

Roy's right about payback.

The only real reason to use panels is for show. For the money you're better off just charging at home (especially since you work at night) using the plug. The $0.10 you spend a day will never pay for a set of solar panels.

My interest is to creating a talking point while replacing the charger for my ACC Batt (I currently have 2 plugs). The only time anyone's noticed my car was electric (without me mentioning it) was the one time I had to charge away from home (at a gas station) so people saw the plug and came to look.

That said, I like http://www.ecobusinesslinks.com/solar_panels.htm for checking prices, though it's tough to get efficiency also.

Does anyone know a similar site that provides efficiency numbers as well?

A few months ago there were panels < $1/watt (where'd they go?!?!) but of course they were 6% which you probably wouldn't want for a mobile application.

rfhendrix

Discussion Starter · #13 · Jan 28, 2011

Thanks for the link. By the way, the solar is not the reason for building this electric Ranger. But I will be buying solar panels anyway for my home (along with a windmill since I live in a kind of wind tunnel here). I will buy panels that I can remove from the vehicle and install on the house if things don't work out. Basically the idea is for experimentation but I want input first so I don't do something that has already failed.

Ziggythewiz

· #14 · Jan 28, 2011

Sounds like a plan. I want to panel my house also, but what I can afford would cover 1/3 of my back roof, which would not make it a DIY job for me. Prices have fallen by 75% in the last 5 years, so I'm waiting to see what they do in the next few.

If I can panel just my patio roof a power the whole (or a significant portion) house it would be a fairly easy DIY job.

rfhendrix

Discussion Starter · #15 · Jan 28, 2011

Ziggythewiz said:
Sounds like a plan. I want to panel my house also, but what I can afford would cover 1/3 of my back roof, which would not make it a DIY job for me. Prices have fallen by 75% in the last 5 years, so I'm waiting to see what they do in the next few.

If I can panel just my patio roof a power the whole (or a significant portion) house it would be a fairly easy DIY job.

Yes, the prices are falling and I think the trend will continue. Some people (like me) are waiting until later this year or early next for some serious price drops on thin film panels.

http://www.green-energy-news.com/arch/nrgs2010/20100083.html

I don't think that solar charging should be written off too soon. Like you I am waiting...

drivin98

· #16 · Jan 29, 2011

Here's a cheaper source for panels. At least it seems to be. http://www.dmsolar.com/solar-panels.html

rfhendrix said:
I did a little figuring and measured my racks. I actually have more like 50 square feet of space for panels. I also have been investigating solar panels. Here is one idea of what is available:

http://www.amazon.com/New-Watts-Solar-Panel-Monocrystalline/dp/B002R1R6NE/ref=pd_sim_sbs_e_3

So I could put 4 of these 150 watt panels at $450 a piece and get 600 Wh. That would seem to be plenty, but at $1,800.00! Anyway, I know that costs are coming down for panels so I think the project is worth considering. By the time I finish the conversion who knows what might be available?

Feel free to correct my math or any of my hair brained ideas.

rfhendrix

Discussion Starter · #17 · Jan 29, 2011

Thanks for the tip! It is looking like I can get about 850 watts that will fit my racks for under $2000.00. As near as I can figure that means approximately 2 hours of sun for 5 miles of driving (at noon).

I know this is all a rough estimate but I really hate to see all of this California sun go to waste. I do think I know one practical application all ready and that is a small panel to supply the 12 volt system.

I have almost decided on a WarP 9 motor and a Curtis 1231C controller. Any thoughts on my choice?

Sunking

· #18 · Jan 30, 2011

rfhendrix said:
It is looking like I can get about 850 watts that will fit my racks for under $2000.00.

Just how did you figure that and using what solar technology?

The most efficient panels on the market are Sanyo HIT series at 17%. To get 800 watts using them requires a minimum of 54/ft2. Using a panel with less efficiency over the same area will yield less.

I do a lot of off-grid battery systems and it doesn't look like you factored in charge efficient, charge controller efficiency, wiring losses, tilt angles, negative temperature coefficient, and time of year.

If you mount the panels directly to the surface, you are going to loose a lot of power from heat.

Anyway in SoCal with 0 degree tilt angle the worse case Sun Hours in December is 2.6, and 6.6 in July. So taking just charge controller and charge efficiency into consideration a 800 watt panel can generate up to 800 watts x 2.6 hours x .8 = 1664 wh in December, and 800 watts x 6.6 hours x .8 = 4224 wh.

rfhendrix

Discussion Starter · #19 · Jan 30, 2011

Sunking said:
Just how did you figure that and using what solar technology?

The most efficient panels on the market are Sanyo HIT series at 17%. To get 800 watts using them requires a minimum of 54/ft2. Using a panel with less efficiency over the same area will yield less.

I do a lot of off-grid battery systems and it doesn't look like you factored in charge efficient, charge controller efficiency, wiring losses, tilt angles, negative temperature coefficient, and time of year.

If you mount the panels directly to the surface, you are going to loose a lot of power from heat.

Anyway in SoCal with 0 degree tilt angle the worse case Sun Hours in December is 2.6, and 6.6 in July. So taking just charge controller and charge efficiency into consideration a 800 watt panel can generate up to 800 watts x 2.6 hours x .8 = 1664 wh in December, and 800 watts x 6.6 hours x .8 = 4224 wh.

I agree mostly with your numbers. I am doing rough estimates here for planning purposes only. I figured I can get these panels (for example) that you suggested: http://www.solarpanelstore.com/sola...yo-hit-power.sanyo-hit-power-200w.info.1.html

They are 215 Watt each and measure 31.4X62.2. I can fit 5 of these panels on my racks with not too much overhang. Also The whole idea is to get as much use of the sun as I can. I understand that there will be times when I will have to use the plug. Another advantage to solar panels on the racks is I won't have to look for shady places in parking lots anymore.

Thanks very much for your help. I certainly want all the downsides before I make a final decision.

rfhendrix

Discussion Starter · #20 · Feb 5, 2011

I found this Ranger that is almost exactly what I envisioned. So it does seem to be practical:

http://evalbum.austinev.org/838

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