Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Solar car just toured the US, and will start production next year

singularityhub.com

Post reply on HN
Print view View original

81–90 of 90 posts

Re: Solar car just toured the US, and will start production next year

#81

Post by Schroedingersat »

jeffbee wrote: post #44
Retric wrote: post #33

Earlier quoted context omitted.

The advantage of a solar car has little to do with saving trivial amounts of electricity. IMO, the best use case is for a hybrid which isn’t generally plugged in as now you’re saving gasoline which could quickly pay for the panels. More widely for EV, there is no need to worry how much charge you lose when parked for long periods. Not needing to worry about running the heater or AC during a traffic jam. Being less de…

Why would the panels improve? Monocrystalline silicon cell efficiency has been about the same since the 90s: 15-20% for commercial cells, up to 26% in the lab.

Mono cells haven't been affordable for more than about 8 years. In the 90s it was 8% poly cells in anything affordable. Now you can get 22-24% glassless cells for a dollar or two per watt retail (or much less in bulk).

Much work is being done to commercialise hybrid tandem cells with growing confidence they'll be here this decade. You could similarly say "polyjunction cells have been about 32% in the lab since the 90s" once they are dominant.

Similarly boosting coverage ratios from the 70% of painted area or so of the current three concepts to 95% is possible now but not economic. As are thin film 10% efficient transparent cells in lieu of tinting over the side and rear windows.

A 40% improvement in car efficiency (the sion is heavy and boxy so there's room), with a 40% improvement in coverage and a 30% improvement in panel efficiency (or 50% in poor weather where it matters) would take it from 'okay, I guess that kinda maybe works sometimes' to 'when was the last time I plugged it in outside of a road trip?'

Re: Solar car just toured the US, and will start production next year

#82

Post by potatochup »

Schroedingersat wrote: post #61
potatochup wrote: post #8

Earlier quoted context omitted.

Lots of extra cost + weight + complexity for marginal benefit. In very specific scenarios it makes sense, but it's usually better to just put the panels on your roof. Most people when shopping for EVs are concerned primarily about single charge range, which solar panels don't really help with. I'm interested to see what these companies come up with, but the proof will come if these companies are still around in 5-10…

500W of cells is about 1kg with another kg of resin on top if there's a surface to bond them to. And costs about $100

$100 + labour for assembly + testing to make sure the panel works + the cost of an extra DCDC converter + wiring to the roof + supply chain risk with all the above parts. Toyota tried it for a while, but I don't think any new Prius models have a solar roof.

Re: Solar car just toured the US, and will start production next year

#83

Post by Schroedingersat »

potatochup wrote: post #82
Schroedingersat wrote: post #61

Earlier quoted context omitted.

500W of cells is about 1kg with another kg of resin on top if there's a surface to bond them to. And costs about $100

$100 + labour for assembly + testing to make sure the panel works + the cost of an extra DCDC converter + wiring to the roof + supply chain risk with all the above parts. Toyota tried it for a while, but I don't think any new Prius models have a solar roof.

Which are all quite minimal costs compared to many other features with very little or negative utility.

Like anything with cars it's purely a matter of fashion, ego, and perception. Noone who isn't making a purely emotional decision buys a new car. Adding a thousand or two and 5kg is completely irrelevant. If people don't percieve an extra 10-20 miles a day as worth the ugly blue rectangles, then the one with them could be 200kg lighter and $5000 cheaper and it still wouldn't sell.

Re: Solar car just toured the US, and will start production next year

#84

Post by joshu »

dreamcompiler wrote: post #55
joshu wrote: post #40

a average fullsize car has approximately a 7 square meter roof. assume we get 100% of that. times solar gets maybe 200 watts per square meter = 1.4kw. times 6 hours of full solar (if you are lucky) = 8.4kwh. divided tesla model 3 gets 2.4 kwh per mile (per below) ~ 4 miles range?

No car has a 7 square meter roof. 1 square meter would be common, but not 7.

I was being very, very generous and converted average length times average width. One or two square meters tops is more reasonable.

Re: Solar car just toured the US, and will start production next year

#85

Post by cjtrowbridge »

jeffbee wrote: post #24
cjtrowbridge wrote: post #5

This has always seemed like the most stupid-obvious idea to me. It's amazing to see some recent examples getting closer to production! There are also mod kits available for some EVs which allow you to attach solar body panels that charge the propulsion batteries. And we have some examples of fully solar-powered EVs that have empowered nomads to travel the world without refueling or charging from electric grids. The f…

It only seems obvious until you try to build one. The people in the "Sunrayce" have been doing this for 30+ years. What you get is a hugely inconvenient fared e-bike with no night capabilities. The amount of sunlight that hits a car-sized object just isn't that high. Everyone is the real world is better-served by a regular old bicycle, or an electric car. There's no innovation here. The economics of solar panels are…

I did build one so thanks for sharing your opinion but go try it yourself and see how easy it is.

Re: Solar car just toured the US, and will start production next year

#86

Post by cjtrowbridge »

throw827474737 wrote: post #21
anamexis wrote: post #7

Earlier quoted context omitted.

How are people traveling the world with "up to 40 miles per day in optimal sun conditions"?

Google average commute times snd distances, you will be surprised even for the US.

As someone who worked at America's only electric vehicle charging manufacturer, the average commute is about 30 miles. With EVs like the Bolt getting 3.9mi/kwh, that comes to 7.6kwh/day. At an average daily solar production of 5 hours at rated capacity, that's 1520wh of production capacity or about a hundred square feet; less than a third the surface area of a normal parking space.

Re: Solar car just toured the US, and will start production next year

#87

Post by cjtrowbridge »

kQq9oHeAz6wLLS wrote: post #10
anamexis wrote: post #7

Earlier quoted context omitted.

How are people traveling the world with "up to 40 miles per day in optimal sun conditions"?

They didn't say how long it would take...

Recouping daily commutes with solar is trivial.

Re: Solar car just toured the US, and will start production next year

#88

Post by cjtrowbridge »

twblalock wrote: post #39
cjtrowbridge wrote: post #5

This has always seemed like the most stupid-obvious idea to me. It's amazing to see some recent examples getting closer to production! There are also mod kits available for some EVs which allow you to attach solar body panels that charge the propulsion batteries. And we have some examples of fully solar-powered EVs that have empowered nomads to travel the world without refueling or charging from electric grids. The f…

> The fact that this is not already normal is insane. I don't know anyone who would want to buy the car in that article. I know plenty of people who have EVs, and I have one too, and still I don't think a single one of my EV-owning friends would buy that car. It's too compromised. What makes a lot more sense is to put the solar panels on your roof and use them to charge a normal EV, all of which are better at being c…

You don't seem to understand the argument. Your car is covered in body panels; those panels could be producing the power to recharge the car. It doesn't matter what the car looks like; any car could work this way.

Re: Solar car just toured the US, and will start production next year

#89

Post by cjtrowbridge »

yunwal wrote: post #22
colinsane wrote: post #18

Earlier quoted context omitted.

depends on your neighborhood/city. a lot of places in the US make heavy use of street-side parking. at the least, it does position itself counter to any push at more efficient land use in cities.

Street-side parking in urban areas still doesn't get direct sunlight more than a few hours a day, since tall buildings block the sun. Perhaps useful in a few west coast cities, but usually it's either "short buildings + garage" or "tall buildings + outdoor parking".

Solar panels don't need direct sunlight to produce power.

Re: Solar car just toured the US, and will start production next year

#90

Post by cjtrowbridge »

potatochup wrote: post #82
Schroedingersat wrote: post #61

Earlier quoted context omitted.

500W of cells is about 1kg with another kg of resin on top if there's a surface to bond them to. And costs about $100

$100 + labour for assembly + testing to make sure the panel works + the cost of an extra DCDC converter + wiring to the roof + supply chain risk with all the above parts. Toyota tried it for a while, but I don't think any new Prius models have a solar roof.

Cars are made by robots. Marginal labor cost is not a thing for car manufacturing.
Post reply on HN