Maximizing solar cells on a Prius

4 hours ago, ronwagn said:

In Australia there is an event where they race solar powered cars between Darwin (in the North) to Adelaide (in the South) - a distance of 3,000 kms or 1860 miles. No charging from power points, just solar panels on the cars. Last one was in 2017 (its not every year) and the winner managed an average of more than 80 km/h - 55 mph, which is not bad going. However, the cars are purpose designed and most of race is across full-on desert. The vast bulk of cars, in contrast, are driven in the city and often at night or left in underground garages during the day. That said, there's nothing wrong with the idea. The question is whether the extra cost would be worth the extra power.

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45 minutes ago, markslawson said:

In Australia there is an event where they race solar powered cars between Darwin (in the North) to Adelaide (in the South) - a distance of 3,000 kms or 1860 miles. No charging from power points, just solar panels on the cars. Last one was in 2017 (its not every year) and the winner managed an average of more than 80 km/h - 55 mph, which is not bad going. However, the cars are purpose designed and most of race is across full-on desert. The vast bulk of cars, in contrast, are driven in the city and often at night or left in underground garages during the day. That said, there's nothing wrong with the idea. The question is whether the extra cost would be worth the extra power.

When I started studying energy there was a lot of talk about thin solar cells that could be printed inexpensively. Like most of the ideas, they haven't panned out yet.  

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This idea won't take off...people would actually have to wash their cars to maintain the efficiency!😂

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5 hours ago, markslawson said:

In Australia there is an event where they race solar powered cars between Darwin (in the North) to Adelaide (in the South) - a distance of 3,000 kms or 1860 miles. No charging from power points, just solar panels on the cars. Last one was in 2017 (its not every year) and the winner managed an average of more than 80 km/h - 55 mph, which is not bad going. However, the cars are purpose designed and most of race is across full-on desert. The vast bulk of cars, in contrast, are driven in the city and often at night or left in underground garages during the day. That said, there's nothing wrong with the idea. The question is whether the extra cost would be worth the extra power.

That race, is a copy of solar challenge in the USA.  Well moved from the USA to Aus for more consistent sunny weather.  The "cars" are effectively lightweight tricycles(seating one lightweight human) with giant tilting solar "roof" to maximize angle to the sun.  Not sure if this option was removed(think it was).  And they are maximum size.  So, 8 ft wide by 15ft long.  Try parking that bus as your daily commuter...(think size was shrunk)   Solar cells got better and race rules changed.  Down to 6 square meters last I knew and forced to be more "vehicle like" instead of a lifting body "car".  Of course this just means everyone made a "van". 

Still gets down to this map:

14.2-Global-Solar-Potential-Updated-1024

You can do solar in the Red. Orange, if you are rich and only want power for ~6-->8 months.  Everywhere else?  Good luck. 

Note where humanity lives.

Solar cells on a car are better than nothing, but without cooling of the cells they will DIE very quickly(2 years max).  This is a massive gimmick.  Don't kid yourself though.  60KWh battery pack when your car roof is 600W... for 5 hours a day plus a shoulder hour each side on average giving less power so call it ~6 hours. 

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On 7/6/2019 at 4:20 PM, Wastral said:

without cooling of the cells they will DIE very quickly(2 years max).

Interesting -didn't know that but would the car actually moving count as cooling or its gotta be some form of refrigeration??

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3 hours ago, markslawson said:

Interesting -didn't know that but would the car actually moving count as cooling or its gotta be some form of refrigeration??

Last I checked, black objects absorb IR/optical if the car is moving or not... 🙄

Rooftop solar are in sheets spaced OFF the roof and designed to have air gap creating a chimney keeping them much cooler so the cells do not oxidize as fast and die.  You can ameliorate this problem by MUCH superior sealing, using glass etc.  Any panel you buy with plastic front will degrade quickly, but give you excellent results at the beginning.  Those that last?  Use glass fronts and encase the entire back in glue etc.  Those small panels... do not have this usually.  Any of the flexible panels certainly do not have this and die VERY quickly.

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19 hours ago, Wastral said:

Last I checked, black objects absorb IR/optical if the car is moving or not... 🙄

Rooftop solar are in sheets spaced OFF the roof and designed to have air gap creating a chimney keeping them much cooler so the cells do not oxidize as fast and die.  You can ameliorate this problem by MUCH superior sealing, using glass etc.  Any panel you buy with plastic front will degrade quickly, but give you excellent results at the beginning.  Those that last?  Use glass fronts and encase the entire back in glue etc.  Those small panels... do not have this usually.  Any of the flexible panels certainly do not have this and die VERY quickly. 

Very interesting - thankyou.. 

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6 minutes ago, markslawson said:

Very interesting - thankyou.. 

This was THE main problem with early panels.  They were not properly sealed so they allowed oxygen in and the solar cells oxidized and the panels died.  Newer designs, should you buy from a reputable manufacturer, have superior sealing and why they now give 20 year warranty for ~80% power output.  OF course what they do not say, is that superior sealing comes at a cost.  Hotter panels.  Hotter panels means lower efficiency of collecting power.   You can see this, if like me, you buy a flexible panel as its specs are awesome on paper.  More Power/square foot of space.  Of course they die... quickly.  😜

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(edited)

On 7/8/2019 at 7:33 PM, Wastral said:

This was THE main problem with early panels.  They were not properly sealed so they allowed oxygen in and the solar cells oxidized and the panels died.  Newer designs, should you buy from a reputable manufacturer, have superior sealing and why they now give 20 year warranty for ~80% power output.  OF course what they do not say, is that superior sealing comes at a cost.  Hotter panels.  Hotter panels means lower efficiency of collecting power.   You can see this, if like me, you buy a flexible panel as its specs are awesome on paper.  More Power/square foot of space.  Of course they die... quickly.  😜

The cooling factor would lend credence to the concept of floating solar and reservoir or lake covers that also diminish evaporation loss. It might also explain why Arizona is not all solar. What would be the ideal location for solar installations? How much loss in the Death Valley versus high desert? 

Regarding the Prius solar cells. Couldn't a stiff aluminum "second roof" for them be designed for their installation? The space could be minimal and small empty spaces for less lift force. Groove that would run parallel to the forward motion of the vehicle. 

Edited by ronwagn

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On 7/6/2019 at 2:20 AM, Wastral said:

That race, is a copy of solar challenge in the USA.  Well moved from the USA to Aus for more consistent sunny weather.  The "cars" are effectively lightweight tricycles(seating one lightweight human) with giant tilting solar "roof" to maximize angle to the sun.  Not sure if this option was removed(think it was).  And they are maximum size.  So, 8 ft wide by 15ft long.  Try parking that bus as your daily commuter...(think size was shrunk)   Solar cells got better and race rules changed.  Down to 6 square meters last I knew and forced to be more "vehicle like" instead of a lifting body "car".  Of course this just means everyone made a "van". 

Still gets down to this map:

14.2-Global-Solar-Potential-Updated-1024

You can do solar in the Red. Orange, if you are rich and only want power for ~6-->8 months.  Everywhere else?  Good luck. 

Note where humanity lives.

Solar cells on a car are better than nothing, but without cooling of the cells they will DIE very quickly(2 years max).  This is a massive gimmick.  Don't kid yourself though.  60KWh battery pack when your car roof is 600W... for 5 hours a day plus a shoulder hour each side on average giving less power so call it ~6 hours. 

The orange areas are actually still pretty good for solar. Note that Florida is in orange. Solar workers pretty well here year round.

As to wether it is a gimmick or not, that will be determined by price. These cells produce enough power to run the AC so can help with range.

If you park in a sunny spot, it may save 10% on your charging costs.

Here in Florida, panels get an average of 3.3x their watt rating in kWh/day so 800 watts would give about 2.4 kWh if t was panels.

Cut that in half because the car will never be ideally positioned and you have  1.2 kWh a day. 

The average EV commute uses 12 kWh (about 30 miles) so 10% of your energy could come from this.

if it is a $200 option, it might be worth it, if $2000, probably not.

As for the cells, why would the die any more quickly on the roof of a car than the roof of a house?

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11 hours ago, ronwagn said:

The cooling factor would lend credence to the concept of floating solar and reservoir or lake covers that also diminish evaporation loss. It might also explain why Arizona is not all solar. What would be the ideal location for solar installations? How much loss in the Death Valley versus high desert? 

Regarding the Prius solar cells. Couldn't a stiff aluminum "second roof" for them be designed for their installation? The space could be minimal and small empty spaces for less lift force. Groove that would run parallel to the forward motion of the vehicle. 

TBH the money is probably better spent putting the panels on top of the roof of a car lot with grid tie connection and putting in some charger points.  

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