DIY Electric Car Forums banner

1 - 20 of 37 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Hello everybody,

I am new here....

I am a 2nd Year Automotive Engineering Student in India.

I am planning to build a Solar powered Electric Vehicle as my Project.

I dont know which motor should I use or how large a solar panel would I need.

The Details i am sure about are as follows:

1. Its has to be a 2 Seater
2. It should atleast run for 30-50 kms in one full charge.
3. It shall run at a max. speed of 30 Kmph
4. The solar panel should charge the battery in a max time of 6hrs.
5. No transmissions needed( Only for simplicity in design. Might add it if not a big issue)
5. it has to be 4 Wheeled.(No trikes)
6. Width should not exceed 1.5metres


What specifications i need are,
What Motor to use( Kind and Specs)?
What Battery to use(Number,Kind and specs)?
What size of solar panel would be required.?



I know thats a too much to ask,
but if any1 could help me on this,it would be of great support.



Thanks & Regards in Advance,
Crucifier
 

·
Registered
Joined
·
4,007 Posts
1. Its has to be a 2 Seater
2. It should atleast run for 30-50 kms in one full charge.
4. The solar panel should charge the battery in a max time of 6hrs.

What specifications i need are,
What Motor to use( Kind and Specs)?
What Battery to use(Number,Kind and specs)?
What size of solar panel would be required.?
Sorry, does not appear possible to meet your specs. A typical car could hold enough solar panels for about 2 miles of range after 6 hours.

Try searching here for other solar threads, the topic has been pretty well discussed.

As for your specification questions, it will all depend on the vehicle you use as your donor.
 

·
Registered
Joined
·
1,773 Posts
It is not possible to do what you want.

If you could achieve the very elusive efficiency of 125 watt hours/kilometer (200 wh/mile) would require about a 60 watt panel. To go 30 kilometers requires about a 1800 watt panel as long as it does not weigh anything. a 1800 watt panel requires about 12 square meters of surface area.

Realistic efficiency of a professional manufactured EV is around 250 wh/kilometer, and you have very little chance of achieving that high of an efficiency on a student budget.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #4
Sorry, does not appear possible to meet your specs. A typical car could hold enough solar panels for about 2 miles of range after 6 hours.

Try searching here for other solar threads, the topic has been pretty well discussed.

As for your specification questions, it will all depend on the vehicle you use as your donor.
It is not possible to do what you want.

If you could achieve the very elusive efficiency of 125 watt hours/kilometer (200 wh/mile) would require about a 60 watt panel. To go 30 kilometers requires about a 1800 watt panel as long as it does not weigh anything. a 1800 watt panel requires about 12 square meters of surface area.

Realistic efficiency of a professional manufactured EV is around 250 wh/kilometer, and you have very little chance of achieving that high of an efficiency on a student budget.


Thanks to u both for the reply...

So what i get from your replies is that either we have to increase our charging time...(which means some days) to achieve that distance or we reduce the distance...


At the same time it comes to my mind, can we add a plug-in charge option too??
That just expands our range of using the vehicle and keeps the it efficient and non polluting??

I hope this is possible...

So now i would need the specs for a the motor and the battery specifically...

Am waiting!!!!
 

·
Registered
Joined
·
1,773 Posts
So what i get from your replies is that either we have to increase our charging time...(which means some days) to achieve that distance or we reduce the distance...
You cannot increase your charging time with Solar , the SUN GOD will not allow it. With a vehicle you cannot even achieve 6 sun hours.

A trap people fall into is they think if the sun shines 14 hours in a day, a solar panel will produce rated power for 14 hours. That is far from the truth and not even close to real world application. In the lower 48 USA the highest solar insolation is Tuscon AZ is 8.1 sun hours in the month of June at a tilt angle of 0 degrees. In December with the same 0 degree tilt angle is 3.2 Sun Hours.

At the other extreme is Seattle WS June Sun Hours 5.1 Sun Hours in June and 0.9 in December

Depending on what type of charge controller and battery combination you use, efficiency on the low end using a series type charge controller (PWM) and lead acid batteries is 50%, at best with MPPT charge controller and lithium batteries as high as 80%.

So a 100 watt panel in Tuscon in June can produce as much as 650 watt hours using MPPT and Lithium. Or as little as 45 watt hours in Seattle WS using a PWM controller and lead acid battery. Reality is neither is acceptable and way to low. It goes to from horrible to non existent.
 

·
Registered
Joined
·
4,007 Posts
Thanks to u both for the reply...

At the same time it comes to my mind, can we add a plug-in charge option too??
That just expands our range of using the vehicle and keeps the it efficient and non polluting??

Am waiting!!!!
You can do an EV conversion like most of the members here, and add some novelty solar panels for a slight range increase. You will primarily charge the car via the plug, and the panels may cover 5-10% of your charging needs.

Another option is to just use solar to charge your 12V system, as I have done. No 12v charger or DC - DC converter needed, so the panel pays for itself in both cost and weight.
 

·
Registered
Joined
·
514 Posts
solar powered, 30kph, 2 seater, ultra low-weight. Sounds like a solar challenge vehicle.
Your primary focus will be drag (air and rolling) and following that is mass (lacking it)


If using perfectly flat roads, i think its possible. If its to be used in everyday traffic, it is not likely to work out. Harsh acceleration, erratic stopping etc drive up the watt/hour per distance unit.

edit:just What about un-folding a large pv panel? That way you're not restricted entirely by surface area.
 

·
Registered
Joined
·
1,773 Posts
Another option is to just use solar to charge your 12V system, as I have done. No 12v charger or DC - DC converter needed, so the panel pays for itself in both cost and weight.
It is impossible for solar battery systems to ever pay for themselves, especially in a mobile system. It will cost you a minimum of 10 times more than commercial power.
 

·
Registered
Joined
·
4,007 Posts
It is impossible for solar battery systems to ever pay for themselves, especially in a mobile system. It will cost you a minimum of 10 times more than commercial power.
I'm not talking about the energy cost savings, I'm talking equipment. What is the average cost of a 12V charger or DC-DC converter?
 

·
Registered
Joined
·
1,773 Posts
I'm not talking about the energy cost savings, I'm talking equipment. What is the average cost of a 12V charger or DC-DC converter?
Fair question.

A quality 12 VDC 10 amp AC charger cost $50 to $75. It can supply full power 24x7x365.

A 12 volt solar panel that can supply 10 amps for a couple of hours per day (140 to 200 watt panel) cost $150 to $400, plus the cost of a charge controller which cost about the same as the AC charger.

Any questions?
 

·
Registered
Joined
·
4,007 Posts
Fair question.

A quality 12 VDC 10 amp AC charger cost $50 to $75. It can supply full power 24x7x365.

A 12 volt solar panel that can supply 10 amps for a couple of hours per day (140 to 200 watt panel) cost $150 to $400, plus the cost of a charge controller which cost about the same as the AC charger.

Any questions?
The 5 watt solar panel I bought for $20 or $25 provides more than the 45 whrs per day I use in the 12v system. Running lead there's no need for a charge controller for a small panel.

So for a low-draw electrical system, solar can provide the necessary power at half the cost without needing to steal anything from the traction pack. I'm sure you'll happily tell me what's wrong with that.
 

·
Registered
Joined
·
1,773 Posts
The 5 watt solar panel I bought provides more than the 45 whrs per day I'm sure you'll happily tell me what's wrong with that.
I will be happy too, the math cannot work. No place on earth has 9 Sun Hour Days. Well maybe around the equator, but no place in the USA, not even Arizona or Hawaii

If this is a standard 36 cell panel made for 12 volt battery systems connected directly to the battery, then you have turned it into a 3.5 watt panel by operating the panel below Vmp of 18 volts. Lastly once you take Lead Acid charging efficiency into account (80%) about all you could get is 10 to 15 watt hours out of it on a good summer day. Winter non existent.
 

·
Registered
Joined
·
4,007 Posts
Regardless of what you think the numbers should be, this 5 watt panel is the only power my 12v system has received since April. Maybe it's because solar insolation in TX is likely at record highs, or maybe the panel was underrated at 5w, but it works.

Also, trickle charging is more efficient than other charging due to absorption rates. It's like a sponge soaking up water from an eyedropper vs a hose.

 

·
Registered
Joined
·
8 Posts
Discussion Starter #14
Hmmmm....


Did not have time to quote for replies...


So now my understanding of ur comments suggests me that i have to have a parallel charger(plug-in type) along with the solar panel.

Could you please first tell me how many batteries would be required & what spec to run the car 50kms.???
& also gimme a suggestion for the motor too....
 

·
Registered
Joined
·
4,007 Posts
So now my understanding of ur comments suggests me that i have to have a parallel charger(plug-in type) along with the solar panel.

Could you please first tell me how many batteries would be required & what spec to run the car 50kms.???
& also gimme a suggestion for the motor too....
Correct. The types of batteries and other gear you need will depend on the vehicle you use. Do you have a car in mind?

30-50 km would be much easier had using lithium batteries as opposed to lead acid, what kind of budget do you have available?
 

·
Registered
Joined
·
8 Posts
Discussion Starter #16
Correct. The types of batteries and other gear you need will depend on the vehicle you use. Do you have a car in mind?

30-50 km would be much easier had using lithium batteries as opposed to lead acid, what kind of budget do you have available?

I am thinking of making a fresh chassis out of steel pipes.
No donor car needed. Would start afresh

my budget is somewhere around Rs.1,20,000/- or US$2500

out of which, the chassis would take up around Rs.30,000.

so i need to find the motor and batteries in the amount of Rs. 60,000.

Waiting for your reply...
 

·
Registered
Joined
·
8 Posts
Discussion Starter #18
What is the intended purpose of this vehicle? Street driver? At least in the US, it is far more expensive to build from the ground up than to use a pre-built, used vehicle.
No. I just want to build it as a showcase vehicle. It would be driven mostly in the university where I study,n once will be displayed at the New Delhi Auto Expo in 2012.

Thats all.
But it should be reliable. :p :D
 

·
Registered
Joined
·
4,007 Posts
So it needs to be reliable. Does it need to be legal? Are there standards you have to build to?

What are your performance needs?
You said 30-50km, is that necessary for a show vehicle?
Max speed?
Acceleration?
 

·
Registered
Joined
·
8 Posts
Discussion Starter #20
So it needs to be reliable. Does it need to be legal? Are there standards you have to build to?

What are your performance needs?
You said 30-50km, is that necessary for a show vehicle?
Max speed?
Acceleration?
does not need to conform to any standards
the range is required.
max speed need not exceed 30kmph
accelaration should be just what is required.
 
1 - 20 of 37 Posts
Top