Are Solar Cars figments of imagination or science thriller stuffs?
I have made a back of the hand calculation about running cars on solar power.
A gallon of gas is 115,000BTUs or 34kwh(3413 BTUs=1kWh). Running at 60mph,the car consumes gas at 3 gallons per hour. Efficiency of combustion engines is around 15% so, the energy required by a car is roughly 34*3*0.15 kwh ~ 15kwh.
The peak rate of incident solar energy ~ 1kW/sq m. The surface area for solar cells on cars ~6 feet*3 feet~1 sq m. So solar energy incident is 1kW*3600=3600kwh. So at this rate the minimum efficiency of a solar cell required is 0.42%. The current efficiency of cheap solar cells is much more than this.
This may seem surprising, but there are many assumptions in this calculation.
The actual area will be much much less.
For a realistic advanced solar cell, http://www.gepower.com/prod_serv/products/solar/en/downloads/gepvp200_datasheet_600.pdf the peak power is 200watt with an area of 1.4 sq m or 140 w/sq m. So energy delivered by this solar cell 504 kwh/sqm
It seems that even with the current technology we can have cars running entirely on solar power. I am amazed that there are no cars as such!!!!!
PS: 1) I think apart from the solar cells, the storage of solar power is difficult which contributes to the problem
2) Rather than mounting ugly solar panels on cars. The cars can run on batteries which can be charged at solar charging stations akin to our gas pumps. The charging stations can have huge panels to harvest solar power.
3) Wind/night/rain might be a problem. But at least they can run on solar power during the day according to my analysis
Friday, October 3, 2008
Why no Solar Cars?
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3 comments:
does the incident solar energy indicate amount of energy available in the infrared range?
this is nearly 50% of the total solar power incident on the earth and it goes untapped because semiconductors have relatively poor absorption coefficients in the infrared range.
a guy called ted sargent at the university of toronto demonstrated the use of infrared colloidal quantum dots that harness infrared power to double the efficiency as compared to existing solar cell tech.
This happened in 2005. What was really good about this was that being in colloial state, they could carried around in a liquid polymer base and could be spray painted. once solidified, you have a thin sheet of a double efficiency solar cells that can be deposited on any surface, flat o otherwise. you just need to hook up wires and use it as a battery after making some minor modifications. I dunno whay that hasnt gone ahead either.
The problem of solar enrgy is cost--...you did not calculate cost--
....you actually need big concentrators (very very big!!!)...and you have to take with car--that needs huge power. And also when you start the engine you need very high energy density, which is not achievable yet with solar power--only fossil fuels can provide that.......
@ganesh
I calculated based on total incident power. For that the efficiency required is 0.42%. The efficiency rating of all cells is based on total incident power. So even then it doesnt matter.
@ arli
good point.. thats why total solar cars are I think impossible. My analysis was only for maintaining the speed. Even if solar power can maintain speeds I think huge savings can be obtained. And concentrators are not required to get an efficiency of 0.42%. Neither are these very costly. Organic solar cells deliver 4-5%.
But still as I have mentioned in my post. The best thing to have is solar power stations where batteries can be recharged. So the need of the hour are better batteries.
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