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Solar cell roofs for EV cars.

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BrianHG:

--- Quote from: raptor1956 on April 01, 2018, 04:43:06 am ---Excuse me?  Australia has some of the highest solar irradiance on the planet.  Your winter will have fewer hours of sunlight just as happen EVERYWHERE on the planet.  Are you saying you have non-stop rain in the winter.  Please point me to the data you base your 10% statement on.

Take a look at this -- took 10 seconds on Google to find.

https://www.altestore.com/howto/solar-insolation-map-world-a43/


Brian

--- End quote ---
You can't optimally tilt a solar panel on a car.  It wont be aerodynamic & what happens when you drive in another direction?  Or if there are trucks to the left or right of you, or you are driving in the city where there building lining the streets?  That map is for optimally tilted solar panels without obstructions as it says just below it.

raptor1956:

--- Quote from: BrianHG on April 01, 2018, 01:12:39 pm ---
--- Quote from: raptor1956 on April 01, 2018, 04:43:06 am ---Excuse me?  Australia has some of the highest solar irradiance on the planet.  Your winter will have fewer hours of sunlight just as happen EVERYWHERE on the planet.  Are you saying you have non-stop rain in the winter.  Please point me to the data you base your 10% statement on.

Take a look at this -- took 10 seconds on Google to find.

https://www.altestore.com/howto/solar-insolation-map-world-a43/


Brian

--- End quote ---
You can't optimally tilt a solar panel on a car.  It wont be aerodynamic & what happens when you drive in another direction?  Or if there are trucks to the left or right of you, or you are driving in the city where there building lining the streets?  That map is for optimally tilted solar panels without obstructions as it says just below it.

--- End quote ---


No, you can't optimally tilt the solar cells on a car -- that's why you'd cover the whole thing not counting the glass.  So, if the Sun is hitting the drivers side that side produces max power and the passengers side produces almost nothing.  Also, given the option you'd want to use the most efficient cells you can.  A small car won't provide very much surface area for solar cells so it's at the least practical end whereas larger vehicles tend to have much more surface area to work with.

If you imagine a small car with 4m^2 on the top with 3m^2 on each side or a total area of 10m^2 and 20% cells you could if all sides were fully illuminated produce 2KW.  In practice the top and one side will be illuminated and neither at a normal angle so figure 70% for both top and one side -- about 1.4KW x .7 or about 1KW.  Over a day in the parking lot at work the car might receive 6KWHr or more and for many folks that could equal half or all the energy needed for the commute home.  Also, with some additional smarts the car could be programmed to run a fan to keep the interior cooler and then fire up the AC a couple minutes before you get in for the drive home.

One area that needs work is making solar cells less obvious so that they are not noticed.  One of Musks businesses is solar roof tiles for your home that do not look like solar panels at all -- you would not know by looking at them.  They are not terrible efficient, however.


Brian

raptor1956:
I should add that there has been some work into making glass that produces some amount to solar electric output primarily for use on large office buildings.  I can imagine the efficiency of such glass would be much less than 5% but anything gained would be a plus.  There is a fair amount of glass on cars and SUV's so even the relatively small output would be in addition to the main cells over the rest of the car.  This could increase the total energy produced by 20% or maybe more.  So, in combination with the main cells the total daily output could exceed 7KWHrs.  The Telsa cars seem to average about 360WHrs/mile so 7KWHr could power the car for over 19 miles (31km) -- I'd wager that the majority of people live closer to work than that.


Brian

BrianHG:
What if my employer has given me a dedicated parking space indoors?
Parking outdoors in winter means snow and cold, where as snow also will cover the solar cells...
What if my given parking spot is in the shadow of the building, or under a shadow cover to keep the car from getting too hot in the sun?
What equates to less power being lost, being in the sun and using more electricity than the solar cells produce to keep the interior from burning up, or, parking in the shade and forgetting about running the AC while parked?

raptor1956:

--- Quote from: BrianHG on April 05, 2018, 10:41:53 pm ---What if my employer has given me a dedicated parking space indoors?
Parking outdoors in winter means snow and cold, where as snow also will cover the solar cells...
What if my given parking spot is in the shadow of the building, or under a shadow cover to keep the car from getting too hot in the sun?
What equates to less power being lost, being in the sun and using more electricity than the solar cells produce to keep the interior from burning up, or, parking in the shade and forgetting about running the AC while parked?

--- End quote ---

If you park indoors you won't get any energy from the Sun -- this isn't rocket science! 

In a prior I mentioned you could run a fan to reduce heat build-up and then perhaps, a minute or two before the owner arrives to drive home power up the AC to cool things down -- I did not say to run the AC ALL FRICKIN DAY!.  In places where heating would be an issue, like Phoenix in the summer, you also have a very high solar flux meaning you're generating a lot of power/energy.  In places where heating is less of an issue you generate less power/energy but also need less.  And yes, when the car is covered with snow you will generate less power/energy -- again, this isn't rocket science.

But, being able to generate enough energy to drive home all on the Sun's dime is not a bad deal now is it.

In one of my last posts I mentioned solar glass and while that's still a bit off and not likely to be as efficient as regular cells the calculations made by the developers are higher than I would have imagined.  They indicated that if all the glass in office building etc were of the solar glass type that could generate over 40% of our entire energy needs -- that's higher than I would have imagined and would suggest my calculation of an additional 20% for a car may be an underestimate by a factor of 2.  If so then a typical small car might receive 8-9KWHrs over the day and as the efficiency of solar cells increase that number would also increase.

The very northern climes are not the ideal location of solar but even in Canada it will, in time, produce a substantial fraction of all the energy needs.  Given enough time it will generate just about all of it.


Brian

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