Hacker News Reader

Comment by xyst | Hacker News Reader

The car company likely won’t have this as an official add on because of the obvious safety issues. Even in its folded up state, this presents a significant risk to others on the road in case of an accident (ie, decapitation, death, impale). Higher the speed (highways), the higher the chance of it becoming a projectile missile.

Also what kind of weight is added here? Solar panels are heavy af. The mileage added via roof charging is significantly reduced due to less efficiency.

View on HN

Not to mention drag and lift. This thing is very likely a net loss of efficiency while driving, even in full noon sun on a cold day, possibly a very large loss of efficiency.

I hadn't even considered lift. This got out a massive wrong in his roof and has lost most of his traction.

Lucky for him he also installed a massive aerodynamic brake

The vehicle is not driven while it's unfolded. Folded up, it looks to be a bit worse than a typical rooftop cargo carrier. It would not be a "wing".

You don't have to be more efficient while driving if the energy is "free" from while not driving, you just have to generate enough energy over the day to make up for (and then some) the efficiency losses. At "20-70 miles per day" of charge from the solar panels that is happening with any kind of normal driving habits.

Putting solar panels to that use is preventing those same panels to be used any other more energy-efficient arrangement (e.g. a car roof). So it's a net loss.

Solar panel production is limited by demand not a lack of raw materials or something.

You don’t need to worry that installing solar in less than ideal conditions will prevent highly efficient grid scale installations.

> At "20-70 miles per day" of charge from the solar panels that is happening with any kind of normal driving habits.

It's absolutely not doing 70 miles a day, and given how large and boxy the structure is when folded, the car is probably losing more than that in increased drag unless it's only ever crawled.

If your argument is "the article is just flat out lying" I don't think we have a set of shared beliefs by which we can have an interesting conversation.

All the pictures in the article are the 2000W version while the article is making ass-pull estimates for a 4000W version.

I think "the article is probably bullshit" is pretty fair.

Sure, but the bar for calling an article "probably bullshit" requires more than "well it looks at bit unaerodynamic" and introducing that argument as far down into a comment chain as you did instead of as a reply to the article is just strange.

> All the pictures in the article are the 2000W version while the article is making ass-pull estimates for a 4000W version.

This isn't clear to me? Perhaps the video makes it clear though, I haven't watched that.

I would never expect a car company to sell a solution that looks like this, but integrated into the vehicles body you can remove all the drawbacks but weight (and optimize weight a lot more than the DIY solution can). See what Aptera is doing...

I think this picture makes it pretty clear why integrating solar panels in cars don't make too much sense. If this installation is 4kW and you compare the surface area to one available on the body of the car it comes clear that cost or implementation likely won't recoup investment. Both monetarily and in resource input.

In terms of dollars you should obviously expect more return by putting the same solar panels on a roof instead of a car - they generate the same energy and you aren't adding mass to an object you repeatedly accelerate.

But then you have to charge your car. The win here is convenience. If you average more charge per day than you average driving (and you have a large enough battery to load balance) you practically never have to charge (ignoring outliers like long road trips).

> If this installation is 4kW

It's 2kW.

Net effect is negative even without weight!

Tesla are 2 tons monsters that charge at 100 000 Watts. 100 Watts produced by integrated panels like this, are most likely not even enough to power up battery controller!

If you charge Tesla from normal house plug in cold, 2KW are not enough to heat up battery pack. So car has to use energy from batteries for heating! So "charging" will actually reduce energy!

Small solar panels are great for fixing parasitic battery drain on vehicles though!

If your argument is "the article is just flat out lying" I don't think we have a set of shared beliefs by which we can have an interesting conversation.

The objective would be to do something like the solar roof on the Fisker Ocean. It's funny that Tesla was once invested in solar panel production but now it's a liability that diverts revenue from superchargers.

Reply on news.ycombinator.com