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Discussion Starter #1
Totally pie in the sky thinking - but would love your thoughts on this. If I have a RAV4 Prime parked out in sunlight for about 8 hours a day, would it be worth considering solar charging with panels on car roof, or solar charging station on premise (with hopes employer allows it)? Commute is 20 miles a day total.

Use cases to consider:
  1. charging while in transit
  2. charging with no battery store for panels
  3. charging with small buffer battery on site.

I wish you could have solar roof option on RAV4 Prime :)
 

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Totally pie in the sky thinking - but would love your thoughts on this.

I wish you could have solar roof option on RAV4 Prime :)
Short answer: If you could somehow connect the solar panels on 50 RAV4s you might get a few miles on driving out of one of them.
 
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Short answer: If you could somehow connect the solar panels on 50 RAV4s you might get a few miles on driving out of one of them.
I kind of expected that :) so it then moves on to the subtopics of parking lot solar charging. As I said, a thought experiment - can we rethink charging grid/off-grid ...
 

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The battery holds about 18 kWh. I have a large system on my house's roof. The yearly average generation is 22 kWh per day. But there are 22 large panels. Just maybe one could get the equivalent of one such panel on a car. So about 1 kWh from a full day of charging. But the angle will be flat, which is bad. So, as noted, if one was charging all day long one could get perhaps 2 miles worth of elec. But indeed there are car companies that do offer this I believe. If it can be made integral to the roof (as opposed to an add-on with the extra weight and drag), it might make some sense.
 

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Not exactly what you're talking about, but Electrify America has been rolling out standalone solar powered charging stations, which can give you an idea of the scale of making this work:


They have a 4.28kW solar array that tracks the sun and 32 kWh of on-board battery storage.
 

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^ I want one. How much?
 

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I suspect anything homemade you put on the roof yourself wouldn't produce enough to even cover the additional drag it would create driving :p
Go solar at home and use that to charge battery
 

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It would be cost prohibitive like the one poster said about 22 panel array. I would guess $40,000 to do it because of the current requirement of 220 volt at at least 30 amps. Also it is charged during the evening when you are not using the car and guess what, the sun doesn't shine at night. So big $$$$ battery for storage is needed.
 

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I doubt it was intentional but what I see above the easily $100K+ corporate renewable energy "vehicle" is a likely 50+ year old homeowner's windmill. Quite a contrast.
 
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Just showing what it takes to run a vehicle on the sun.

This is most likely Arizona, a few hundred pounds vehicle that is very cramped and uncomfortable. It is basically a man with wheels and a solar panel.

Didn't notice the windmill, my bad eyes just assumed it was a tree.
 

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Didn't notice the windmill, my bad eyes just assumed it was a tree.
Since everything else is brown except by the windmill it must be at least partially responsible for irrigating that area. So this picture shows the very practical old-tech use of renewable energy compared to a totally impractical demonstration of new tech.

Also, the vehicle should get a ticket for illegal passing on a two lane road.
 

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Well I'm kinda considering installing 3 flexible 175w panels (100*50cm, it fits) on my Prime's roof. During summer, sun is very high up north, and days are very long. I think getting 8 hours at 60-70% would be doable. Drag would be negligible on these 3mm thick panels.

8×3×.175×.66=2.75kwh
60km*2.75/15=11km
I ordered a small 14ft trillium style trailer. I could fit at least 6 more panels there, and get 33km/day.

my daily commute it about 20kms, so it does makes sense, 8 months per year at least.

Electricity is outrageously expensive here at 34c/kwh.
I could generate 3×2.75×8×30×.34=673$ worth of electricity during these 8 months.

But panels orientation worries me, I wonder if some panels surfaces help to be orientation agnostic
 

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The BIGGEST problem with solar on cars isn't really the cost or drag, it's the WEIGHT. Solar arrays weigh a lot, the more often you drive your car, the more the weight penalizes you. The more solar you add, the more weight you have... and the more power you need to overcome the weight. Depending on the efficiency of the panel and how often you drive the vehicle, you could actually be taking an energy hit rather than gain by having them on your roof. It's also unlikely solar arrays will ever be efficient enough with future technology growth to make them worthwhile to be on a cars roof. The other problem with putting panels on a roof is that cars are not always outside... It's a poor engineering/design tradeoff to put them on roofs, and I would bet someone good money that we'll never see them used on car roofs in our lifetime or ever. Same thing goes for battery powered cargo planes and long haul trucking, the weight to power ratio for batteries is never going to be good enough for mass adoption compared to combusting fuels.

What is a smarter from an enginering and design perspective - is to power charger stations with solar. This way you can A) guarantee the panels are always out in the sun, and then B) the panels are not adding weight to a car.

Edit: I'll add, one reason you see solar panels on RV's more often is because RV's generally sit more than they're driven, and they're hard to park in shaded spots :p
 

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Since everything else is brown except by the windmill it must be at least partially responsible for irrigating that area. So this picture shows the very practical old-tech use of renewable energy compared to a totally impractical demonstration of new tech.

Also, the vehicle should get a ticket for illegal passing on a two lane road.
If I remember correctly, the photo is at least a year old, if not older. Taken in Australia, part of an inter-national electrical distance event using solar only. I believe that this was the winning vehicle.

No ticket, Aussies drive on the left.

Have a good day.
 
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The BIGGEST problem with solar on cars isn't really the cost or drag, it's the WEIGHT. Solar arrays weigh a lot, the more often you drive your car, the more the weight penalizes you.
He's talking about a flexible solar panel. Those things are super light. I have a 200 watt one, and it weighs maybe 5 lbs. The biggest issue isn't the weight or air resistance on the roof, it's the assumption that you can get 60 to 70% of the rated power for 8 hours. No ways. Not gonna happen. At STC, most of these panels are rated for half that. And, you'll likely only get that power for a short time period. My 200 watt panel gets maybe 180 watts of power at full sun facing directly towards the sun for maybe several minutes. But, as the panel heats up, efficiency degrades, and the panel loses power.

You're likely to average probably 30 to 40% of the rated panel wattage for the whole day.
 

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Discussion Starter #19
These are good discussions to have, and the conversation on this topic has been good one. Even the tangent on windmill (wind turbine) is a good one - if you wanted to create a charging station with smaller foot print and 24 hour opportunity - a small wind turbine could be a good proof of concept. Energy storage is a critical component to the solution. Also had not considered flexible panels an option, but weight wise might make sense.

also, the holy grail is 100% green source, partial solutions to wean off of grid when possible is a step forward in the right direction.

Texas system of market supply metering is a reality of legally binding bills of 7-10k$ due to a winter storm.

I appreciate the discussions here. I remember MIT solar racers, we are far from the independence, but baby step forward!
 

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He's talking about a flexible solar panel. Those things are super light. I have a 200 watt one, and it weighs maybe 5 lbs. The biggest issue isn't the weight or air resistance on the roof, it's the assumption that you can get 60 to 70% of the rated power for 8 hours. No ways. Not gonna happen. At STC, most of these panels are rated for half that. And, you'll likely only get that power for a short time period. My 200 watt panel gets maybe 180 watts of power at full sun facing directly towards the sun for maybe several minutes. But, as the panel heats up, efficiency degrades, and the panel loses power.

You're likely to average probably 30 to 40% of the rated panel wattage for the whole day.
A 200w?

I see a lot of so-called 250W on the internets, but when you dig the specsheets, they're all [email protected]

The only legit 175W I found is made by renogy, seems high-quality, yet quite a bit over my 1$/W target.

Would you care do give us more details about your pannel?

For the 60-70%, yeah I feared that, it was a top-of-my head estimate.

BTW, I was scanning my Prime with an ODB-II scanner, while scanning for OTC codes, the scanner found (I think, it went fast) a solar controler... it was intriguing. I'll dig further when time allows.
 
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