Is it time to re-visit solar hybrids?
 

I came across this paper a while back:

https://www.researchgate.net/publica...Solar_Vehicles

Since it was written the cost of solar panels has dropped by >90%!

We've seen eletric cars like Sono Sion and Lightyear One have solar panels, but it makes more sense to put solar panels on a non-plugin hybrid since energy in one of those is more valuable, about $0.12/kWh for electricity from the wall and $0.77/kWh for electricity in the car - more than six times as much! (with European fuel prices)

Recently the Hyundai Sonata and Kia Optima hybrids have come out with solar roof options.

No

I think it is interesting, and I didn't know the Sonata had this option.

This is apparently the potential for the 2020 Sonata's Solar Roof Option: "potentially a couple of miles of extra engine-off distance from six hours out in the sun, and up to 700 “free” miles back per year."

Like all these systems, it depends on how much sun you get, how much it costs the customer and manufacturer, and what you define as useful.

https://www.greencarreports.com/news...ing-solar-roof

If one major OEM is doing it, then hopefully others will follow.

Cost isn't the driving factor.

The issue is panel efficiency. At <20% efficiency, you need too much surface area to make it worthwhile. Can it make a small difference? Sure. 700 "free" miles is nothing to sneeze at, but when the cost of those 700 free miles is only... .05*700 = $35, it's hard to justify.

If I were living somewhere with a quite constant solar exposure all-year round, a solar hybrid wouldn't be out of question.

Now if a big array of panels could pop out of it all transformer-style, heck yeah!

If I lived somewhere with a constant solar exposure, I’d put the panels on the roof of my house and “solar” charge my car from the grid like a reasonable person.

Which part of non-plugin hybrid did you not understand? No one cares what a person who can plug their car to the wall would do, this is interesting to people who otherwise have to get all their car energy from gasoline.

The price drop during the last decade has brought the returns of car solar to levels comparable to the stock market.

Considering I bought a 300 watt flex panel for $65 (supposedly over 20%EFF)

Who cares?

The benefit
of the 12 volt surviving
Of Possible cooling fan operation
And added free range is worthwhile
And In the winter you could likely use excess power to power the seat heater
Seems like a no brainer as a gimmick and convience option

It’s all about cost, as manufacturers offer it you will drive cost down and reliability up.


I think of all the new car option costs and have to say no one seems to care about buying the $2000 premium audio I don’t see why this is any more efficient

Solar roof panels would be a must if I lived in a house instead of an apartment, even though solar exposure may vary through the year. But if it could also be effective to have it on a vehicle, just like some campers use in their vans for auxiliary power, I would be inclined to give it a try.

That is walletgasmically cheap!

Assuming you could use all the energy, the effective sun hours you need to recoup your investement is:

Europe: 285
Hawaii/California: 577
Texas: 1024

And assuming $0.13/kWh at home we could lose this much of the potential energy and still be better off with the panel on the car than at home (assuming we are unable to plug the car in):

Europe: 83%
Hawaii/California: 65%
Texas: 38%

Of course there are more costs than just the panel, but that is also true at home.

Some info from various reviews:

• The solar roof is only available on the limited trim level which is rated at 47 mpg combined vs 52 mpg for the base trim.
• It is 205 watts
• The roof adds 66 lbs.

As to how much power it can supply - Hyundai's statement to Jalopnik:
I would be interested to see what it would cost as a stand alone option. There is no way I would buy a $5000 package to get it.

Even at $3 a gallon that is a savings of about $0.12 a day under perfect conditions.

It also means I would have to park on the roof of the parking garage. In the summer my car would be 130 F when I got out of work instead of 80 F. How much of that 0.9 kW solar energy am I going to consume cooling the car back down to 80 degrees with the A/C?

200 watts is more than most people think. I have 200 watts of solar on the roof of our campervan and it will run our refrigerator even during a week of overcast days and rain.

Yeah, so still no.

Even Mark Watney stops and sets up the solar array when it's time to charge despite limited oxygen. Integrated solar is usually dumb.

solar panels on a car lol

no will not work


it's just as bad as solar road ways idea it's better just to store it(to charge it later) and/or have them roof mounted..

https://ecomodder.com/forum/attachme...1&d=1599459306

The main reason solar roadways is bad is because the panels have to be made strong enough to drive vehicles on them, turning something dirt-cheap, into something ultra-expensive. Car roofs (believe it or not) do not need to be made strong enough to drive vehicles on them, the panels will just go from dirt-cheap to kinda moderately-priced, and give reasonable returns.

I have recently seen an electric 2nd-generation Smart ForTwo at the parking lot of a supermarket, and it had roof-mounted solar cells. That car belongs to an energy company, and is used for administrative job while also clearly serving as a marketing stunt.

I too would like to get info on these 300 watt flex panel for $65. How big are they?

My car has rather large and reasonably flat roof (and hood, but then there is the mirror effect), and I do not drive it much during the week even in pre-covid times. And I do not have a garage. So if it would be charging itself during the week, it would not hurt my feelings to go grocery shopping on that charge, leaving the engine for when I want to have fun or go far. I probably could get away with non-fun trips with a total range of 30mi in a week.

I never understood why they never brought the Smart Roadster to the US. I guess they expected the typical Smart owner here to be horrified for having something sporty/fun under that brand.

Extraordinarily unlikely you bought a 300W flex panel for $65 especially if it's new. False advertising is rampant on sites like Alibaba/Aliexpress, ebay and Wish. 20% is pretty much the ceiling for the best fixed panels. Flexible aren't better. You probably got a run-of-the-mill 100W panel.

You have to look at the surface area of the panel. If that panel is less than 1.5m^2, no way it's 300W. If flexible, it probably needs to be closer to 1.6 or so.

Sounds like the watt-math I found on the instructions inside the box of the panel I bought and then returned...max no-load voltage multiplied by the max shorted out current it could produce...a good 3x the watts of what it would actually put out.

IIRC there was a Dodge-branded concept car based on the Smart Roadster, but it was never released as a production model. Well, maybe the Smart brand was not so appealing to the performance market there, yet a rebadged (and easily re-skinned to get the family look of regular Dodge models) version could have some better chances to succeed.

Solar car roofs don't make sense in any practical terms unless you have to deal with being away from the grid. It makes for more sense to place panels on a fixed roof optimized for solar exposure, vs. the sometimes and likely far less than ideal exposure of a car roof.

More simply, if you have the grid and can wait for car solar panels to charge the car, you can wait for the car to charge plugged in - from panels working far more efficiently.

Solar car roofs make sense as they liberate one from Big AC's grid. It makes more sense for roof panels to be optimized for Solar exposure, rather than fixed.

What power lost as the house battery transfers to the car batter?

The problem is that most EVs spend most of their time charging at home. So whatever can be installed at home is still going to be more efficient. Likewise, once the car is fully charged, extra energy the solar panels mounted on the roof of it could produce becomes completely wasted. But obviously, any net metering or battery bank at home can keep home panels productive.

I think similar efficiencies are at play with AC charging vs. stepping up voltage for DC charging direct from panels, but I am not certain of that.

I am not saying they could not help or be useful on a car, but rather, for dollars spent on PV panels, there is far far more bang for the buck to be had with permanent home installations.

I was trying for terse-but-balancing commentary. It may have come across as snarky contrarianism.

I think there's a case for both, with the house and car load-balancing with any excess power mining Bitcoin. ;)

As far as that, how about inductive charging at traffic light left turn lanes?

I say it's a waste of solar panels.
I want to park in the shade in the summer and panels laying flat on a car roof only produce about half of what they are rated for in new mexico in the summer. In the winter it's more like 1/3. Then if you live up north forgetaboutit.

I'd say PV installed in the PNW is a waste period.

As I've been saying, I could install my panels in AZ, the people in AZ could pay a discounted rate for the electricity, and my payback period is reduced. It's a win/win proposition, but instead we like to have 3 different government subsidies pay for doing it the dumb way.

The value proposition just barely broke even after I got 3 different groups of citizens to non-voluntarily pay for most of it. "Hey, help me put these panels on my roof or I'll break yer leg".

Yep. On the best day, my 4.96kW array has only produced 3.8kW here in Eugene. This time of year, even half that peak production does not happen, and when it does, it is fewer hours. (Highest recorded totals this year were 28kWh in June, and 5.3kWh in December, or about $2.80 vs. $0.50 saved on those days.) It produced 4.9MWh for the year, saving just over $490. At that rate, it is going to take 12 years to pay for itself - plus my extra effort to keep them clean.

I would not have installed the panels without the maximum tax credits.

The up side is that panel efficiency keeps going up while costs continue to fall. So there may come a day where we are all just looking for new places to put them, and sure, why not the roof of a car? But I think we are a long way from that.

My 6.4 kW array produced 5 MWh last year, but I started in May. July was my peak, at almost 1 MWh. 220 kWh Nov, and 210 kWh Dec. My estimate was 1 MWh per year, per installed kW.

It will take 12 years to pay for itself, not adjusting for rate changes or opportunity cost of not investing the money into the stock market, which would have been phenomenal in March.

I'm glad I did it for the experience, and it will probably end up at least breaking even financially all things considered. Probably a nightmare when I go to re-roof, but that's future self's problem.

I know a guy who recently got 2 solar panels for his van, in order to provide power for a fridge and other camping appliances. Now it seems like he usually parks it at a different position in order to get a more effective sunlight exposure.

I think inductive charging is a good idea, but I don't understand how it doesn't inductively heat the battery pack or the underside of the car.

I would like to see how they get the solar cells on a solar car so flat and smooth, no-one seems to have done that as a DIY.

I think maybe a boat tailed insight gen1 with roof, hood and boat tail solar cells could get more benefit due to being able to lean burn more often. Possibly 600-800w peak which is around 10% of the required energy at 60mph.

I wonder what the trade-off is between the energy provided by solar panels on a car when the sun is shining vs the aerodynamic loss due to the shape and texture of the panels anytime the car is moving.

In which use cases would inductive charging be preferred to plugging in? Inductive charging is inefficient, and the lost energy does create unwanted heat. It takes an extra 5 seconds to deal with a plug, so I just can't imagine who is so lazy they can't be bothered to do that, especially in comparison to the inconvenience of going to the petrol station and waiting for the pump to dispense the fuel.

The Lightyear One has 5 m^2 of solar panel installed. Under absolutely ideal conditions that's about 1kW.

This was asked in the other solar EV thread, and the answer is it depends. There's too many variables to make a blanket statement, but the question is among the reasons why it isn't "time to re-visit solar hybrids". Placing the weight at the worst possible place, at the highest point on the vehicle, is not good. People would be better served with a 1kW larger battery (perhaps the extra range solar would have otherwise provided) located in the best place to carry weight, the lowest point of the vehicle.

The discussion keeps sliding towards just plugging in instead, but as specified in post #1, and reiterated more and more obviously in post #9 and #16, the suggestion was for cars that cannot be plugged in. This is the sort of car a person who has nowhere to plug-in would get.

It keeps sliding that way because the only scenario solar on a car makes sense is for those who don't have reasonable access to a petrol station or mains electricity, but have a ton of cash to blow on a solar powered car. That describes about 0.0001% of people. The handful of people that need that capability are free to engineer it themselves, or pay Lightyear One a bazillion dollars for a (hopefully) working example.

Taxi ranks and bus stops, older people and non-driveway parking are good examples, in the UK you need so many cables and connectors to unwind to park somewhere and charge, in the UK we have 13amp, 16amp connectors, chademo, j1772 connectors, type 2 connectors, type 2 + DC connectors, plus all the three phase types. Inductive would just be a case of parking and getting out, no forgetting to plug in.

If they are smooth, such as on a solar car, then there is no aerodynamic loss, but there is the difficulty of what to clean them with, some car washes and most car waxes/ceramic coatings contain UV blockers.

Plug in or induction you have to trench to get power to the usage point. You also need an interface to pay to charge. So it comes do to having a charging station with or without a plug and cable.

As for forgetting to plug in - when you drive an EV you don't forget to plug in. It becomes second nature. I didn't forget to plug in once in 39 months I leased an EV.

The OP was about using solar to make a normal non PHEV hybrid just a little bit more efficient. I don't think the economics work for that. Solar mounted on a car is never going to power a normal EV more than a few miles per day.

Even with access to petrol stations it makes sense if the price of gas is high enough, from post #12:

And there is another thing going on in Europe right now, a car that emits 10g/km less CO2 has €950 less penalty applied to it, that alone would pay for a significant solar system on a car.

No, it doesn't. 10 miles of range (optimistically) is like 1/4 gallon of petrol. If my driving needs were so little, I'd take an electric unicycle, bicycle, electric assist... and if my travel needs were greater, then PV would be insufficient.

Nobody is spending $135,000 on a Lightyear One because they can't afford petrol on their 5 mile commute.

As I said, there is no economic reason for PV on a vehicle in any use case unless one has no reasonable access to a petrol station or mains electricity. Even then, they would be way ahead to put the PV in a fixed location and charge their vehicle at that location.

It's a dumb idea except for a slow-moving rover on another planet.

Solar makes sense if you have a lot of roof area and a very efficient vehicle

Like an Aptera (if it ever comes out)