5 ms·

> an induction cook top You make it sound like you're using a lot of power in that bus, but an induction cook top is at most 2-3 KW. That is 4 horse power. If

> an induction cook top You make it sound like you're using a lot of power in that bus, but an induction cook top is at most 2-3 KW. That is 4 horse power. If you want to crawl at 5 mph that might be enough (but not for a skoolie anyway). Cars have a huge power-plant under the hood. 100kW per car, at least. All the cars in a city have far more power than the power plant that supplies the city. Think 10k cars (town)= 1 GW. That is a nuclear reactor... All the cars in the US, 275 million vehicles, at an average of 100KW, have a combined power of 27.5 TW. The total installed electrical power plants in the US are around 0.5 TW. The whole world has only 6 TW of installed power plants. Cars need a lot of power...

kamranjon 6y ago
Are you assuming that the sunlight needs to directly power the car? The idea, and especially with the car in the article here, is that your car can charge over the course of a few days. The power for electric cars is delivered from the battery. The Chevy Bolt for example has a 60kwh battery. If you have 1kw of solar, it will take you 60 hours of sunlight to charge that battery assuming the efficiency of those cells is close to what they're rated for. The car from the article has a 35kwh battery so around 35 hours of sunlight to fully charge on 1kw of solar. If I drive ~100 miles in the city every week, and the car from the article gets the claimed 200-220w/m2 of solar - It's definitely feasible to recoup your entire driving usage by it just basking in the sun when you aren't using it.
- flavius29663 6y ago
  I am saying it's not really feasible. To charge a 35kWh battery in 35 hours, you need a constant 1kW. 1kW is a LOT when it comes to mobile PV panels, converted bus campers don't have that much usually. Earth receives 1kW of power from the sun, per square meter. A solar panel has an efficiency of 20%. So under ideal conditions, sun directly at 90%, no shades, you get 200W per sqm. Now, you have shades, less than 90% angles, dirt, etc. On average in the US, the capacity factor of solar PV farms is 25% (includes day/night changes). You will get less on your car, but let's say you do get 25% capacity factor. That leaves you with 1000 * 0.2 * 0.25 = 50W per square meter, 24/7. In a week that is 8400 Wh per square meter. To charge the 35kWh battery once a week, you need 35/8.4 ~ 4 square meters. 4 square meters is plausible. You could say that the car has more space for PVs, but you kind of have to mount them such that they have a decent angle, otherwise their efficiency drops 10 fold. In the case of Chevy Bolt, if you have a 1kW of PV panels, used in ideal conditions, you would need 1kW * 0.25 * 240h = 60kW. 10 days to fully charge the 60kWh battery. If you manage to install 1kW (4-5 square meters) of panels on a volt at ideal conditions (tilted 30-35%), then you could drive it 200 miles every 10 days. On the other hand, if you only drive 20 miles a day, you could recharge at a power outlet and 60kWh would cost you 6 dollars. 6 dollars per 10 days, that means fuel cost would be $219 a year. That is $3200 for 15 years. Is it really worth installing a heavy and complex system on the car if you can achieve the same and better results by just laying the panels on the ground, next to the carport? I am all for integrating solar PV in a lot more things, like house sidings and windows, but putting it on cars is just a PR move.
leoedin 6y ago
Cars need a lot of peak power. They don't use anywhere near that peak power during normal operation. A typical electric car averages 4 miles per kWh. At a speed of 40 miles an hour that's an average power of 10kW - 10% of that 100kW peak power output.
alexisread 6y ago
While you have a point, I'd suggest a solar car is feasible if it is designed lighter ie. an electric bike puts out 250W which is enough to take a rider to 15mph. Something like the Citroen Ami (or electric TukTuk, or any of the small chinese EVs) which weighs 450kg is a halfway house between Teslas and bikes. The Ami can charge off 13A 240V in 3 hours (6kW motor and 5.5kWh battery pack), and is useful for a number of duties eg. school runs, shopping, mobility, bad weather. Obviously the car featured here isn't designed around light weight<->practical charging but I reckon you could make an ultralight design for 4/5 people. The other problem is other larger cars on the road, that's a separate debate from the technical one.

kamranjon 6y ago

Are you assuming that the sunlight needs to directly power the car? The idea, and especially with the car in the article here, is that your car can charge over the course of a few days. The power for electric cars is delivered from the battery. The Chevy Bolt for example has a 60kwh battery. If you have 1kw of solar, it will take you 60 hours of sunlight to charge that battery assuming the efficiency of those cells is close to what they're rated for. The car from the article has a 35kwh battery so around 35 hours of sunlight to fully charge on 1kw of solar. If I drive ~100 miles in the city every week, and the car from the article gets the claimed 200-220w/m2 of solar - It's definitely feasible to recoup your entire driving usage by it just basking in the sun when you aren't using it.

flavius29663 6y ago
I am saying it's not really feasible. To charge a 35kWh battery in 35 hours, you need a constant 1kW. 1kW is a LOT when it comes to mobile PV panels, converted bus campers don't have that much usually. Earth receives 1kW of power from the sun, per square meter. A solar panel has an efficiency of 20%. So under ideal conditions, sun directly at 90%, no shades, you get 200W per sqm. Now, you have shades, less than 90% angles, dirt, etc. On average in the US, the capacity factor of solar PV farms is 25% (includes day/night changes). You will get less on your car, but let's say you do get 25% capacity factor. That leaves you with 1000 * 0.2 * 0.25 = 50W per square meter, 24/7. In a week that is 8400 Wh per square meter. To charge the 35kWh battery once a week, you need 35/8.4 ~ 4 square meters. 4 square meters is plausible. You could say that the car has more space for PVs, but you kind of have to mount them such that they have a decent angle, otherwise their efficiency drops 10 fold. In the case of Chevy Bolt, if you have a 1kW of PV panels, used in ideal conditions, you would need 1kW * 0.25 * 240h = 60kW. 10 days to fully charge the 60kWh battery. If you manage to install 1kW (4-5 square meters) of panels on a volt at ideal conditions (tilted 30-35%), then you could drive it 200 miles every 10 days. On the other hand, if you only drive 20 miles a day, you could recharge at a power outlet and 60kWh would cost you 6 dollars. 6 dollars per 10 days, that means fuel cost would be $219 a year. That is $3200 for 15 years. Is it really worth installing a heavy and complex system on the car if you can achieve the same and better results by just laying the panels on the ground, next to the carport? I am all for integrating solar PV in a lot more things, like house sidings and windows, but putting it on cars is just a PR move.

leoedin 6y ago

Cars need a lot of peak power. They don't use anywhere near that peak power during normal operation. A typical electric car averages 4 miles per kWh. At a speed of 40 miles an hour that's an average power of 10kW - 10% of that 100kW peak power output.

alexisread 6y ago

While you have a point, I'd suggest a solar car is feasible if it is designed lighter ie. an electric bike puts out 250W which is enough to take a rider to 15mph. Something like the Citroen Ami (or electric TukTuk, or any of the small chinese EVs) which weighs 450kg is a halfway house between Teslas and bikes. The Ami can charge off 13A 240V in 3 hours (6kW motor and 5.5kWh battery pack), and is useful for a number of duties eg. school runs, shopping, mobility, bad weather. Obviously the car featured here isn't designed around light weight<->practical charging but I reckon you could make an ultralight design for 4/5 people. The other problem is other larger cars on the road, that's a separate debate from the technical one.