Hacker News Reader

> Why do stupid gimmicks like this? Why not have an efficient device and just charge it from the grid?

I used to have a laptop with dual batteries, so one could swap one battery out with another to have an uninterrupted power supply without having access to the grid. Very few people need an uninterrupted power supply while away from the grid, but some people do. That is why such a design existed. Something like an integrated solar panel may fill a similar niche.

It is also worth noting that a technology should not be dismissed simply because the first iterations appear impractical. If we took that attitude, many of the things we enjoy today simply would not exist. Just think of personal computers from the late 1970's and early 1980's. Few people used them since they were not very practical. On the other hand, that seed of a market both financed the development of the machines we use today and directed the development of the technology towards something we would want to use today. (Put another way: if people did not use that impractical technology in their homes, it likely that computers would remain the tools of large institutions.)

Dell used to offer dual battery bays in its business line like the Latitude C840:

https://youtu.be/9XkeTCIC1TA?t=453

Side note: The clips holding in the batteries were the number one failure mode on those laptops.

IBM/Lenovo themselves supported dual batteries at one point with the Ultrabay expansion slots: https://www.thinkwiki.org/wiki/Ultrabay

You don't need dual batteries for that, just an external USB-C powerpack. And they are pretty common.

Different time, different context.

This would have been around 2010, when powering anything with USB was relatively uncommon. Some USB peripherals required a separate power supply or dual USB connections in order to provide enough power. Devices that charged via USB typically provided a special USB power adapter in order to facilitate faster charging.

Even today, dual battery compartments have marginal utility. Since it is built-in, it offers extended battery life without carrying around extra modules. Spare batteries are mildly more convenient to carry around (no extra cables). Mostly though, it enforces user replaceable batteries.

Cost is probably what killed that project, but it's not entirely stupid, although it would certainly be better with a foldable panel at the back of the screen that can be positioned optimally.

A 30x20cm laptop could get at best 12-10W of sun power with a solar panel on its surface.

You could build a useful laptop with the same spec as a smartphone with a standard 4000mA battery and need about a charge a day in normal use.

Since the exposure of your laptop to the sun would be suboptimal, you may only get 4W for say 5h a day, which seems fairly reasonable and is enough to recharge the battery every day.

Even on bad days, you would probably be able to use your laptop half of the time, which could still be a few hours and enough to make a difference to someone with otherwise no access to technology.

I imagine that in places where electricity is scarce, adults might have different priorities than charging kid's laptop. Maybe the idea is that you leave laptop open in sun if the battery dies and it charges without needing access / permission to use power grid / generators?

>I imagine that in places where electricity is scarce

I think that's what most people in the west imagine and that's why this is a gimmick that resonates with well-meaning westerners. Besides the fact that developing world is a diverse place in all aspects (so the the stereotype you're imaging is wrong for the vast majority of the developing world), communication is such an ingrained human need, that communication devices like smart phones are everywhere.

But none of that matters. These panels just do not work well - or at least as well as you can expect given the surface area and whether or not there's enough sunlight. That's why nobody bothers with building them into devices. Besides you can buy little external solar chargers for real cheap. And the external ones are better than the ones built into the devices because you can angle them, and they aren't a failure point you need to worry about (that is, if they die, your device doesn't need to be replaced), and aren't limited to device size. Also, I don't know why you would want your electronics exposed to direct sunlight... Heat is not good for electronics.

Again, I support low-power, energy efficient devices. There is a very real use case for them, and not just for the developing world. But these gimmicks, like building in solar panels into the device, are dumb.

I am married to a teacher and can assure you that even in 'the West' there are kids without personal smartphone and without a single computer/tablet at home.

No idea whether heat aspect is worked around in OLPC somehow by carefully selecting materials used or whatever, my point is that making these laptops self-sufficient would indeed be useful (if at all possible).

Definitely agree. There is a profit incentive to make laptops powerful but there is very little competition at the low end, unfortunately. I solar powered a microcontroller in indoor light just to prove that powering a computer is possible (96mhz is far more capable than even some early 486 PCs that ran Windows) , and not just a calculator. https://www.youtube.com/watch?v=0ztj_MDNRcI

of course, powering a screen would require much more light, but it's not impossible if there was a full system re-development - from low power monochrome displays to light peripherals. Our group hopes to get a terminal to display on an e-ink, which seems doable: https://forum.ei2030.org/t/paperterm-project-definition-and-...

Also, I don't know why you would want your electronics exposed to direct sunlight... Heat is not good for electronics.

Also UV. It'll destroy plastics rather quickly.

Give them a laptop and put the solar panel on the side? Even in the exact case you're mentioning, they're better as separate devices. (It wasn't done this way because the solar panel would be used for other purposes, but treating the user as hostile is the clearest sign that something has gone terribly wrong in your design process.)

10+ years ago I had a laptop case with solar panels and an outlet. It worked well; could both extend the battery life and charge when not in use. Not mediocre, and I imagine things have improved? There may be better solutions for low grid envs, but this one is viable.

>10+ years ago I had a laptop case with solar panels and an outlet.

Do you think they would work better if they were built into the laptop screen? Because that's what OP was raving about.

You can get batteries and external solar chargers (they are cheap and come in any size you want) if that's what you want to do. Building them into the device is STUPID. For one thing, you would need to put your device in direct sunlight to charge them ... and heat is not good for electronics. Also, the solar array size will be limited to whatever size your device is, that is: "too small".

man, you've got some bones to pick with solar power, don't you?

No. I think it's a perfectly fine technology ... but it isn't a panacea and it doesn't make sense for everything that people are trying to cram it into. Case in point, attaching solar panels to a smart phone or a laptop screen. I've conceded (somewhat) that if you really want to, it makes far more sense to get external panels and just plug them in.

30 years ago I had a credit card calculator powered by a solar panel. Ideal pairing. Viewable screen in direct sunlight too thinking about it.

Calculators need mere microwatts of power to function. A very basic laptop is in the tens of watts.

A difference of many orders of magnitude that you can't compensate by the size of solar panel on a small device.

> A very basic laptop is in the tens of watts

The latest version device in question (the OLPC) is ~5W under normal usage and less than 1W when idle.

Im not sure about an integrated solar panel - im not sure i would want to keep my laptop exposed to the sun - but i was able to keep a 2015 macbook charged with a small solar panel while travelling (approx 4 hours a day of heavy usage).

Obv depends on time of year, location, weather, etc.

But even 1W is several orders of magnitude greater than the average LCD calculator.

It’s interesting that electronic calculators are basically the only type of devices ever to have successfully powered by integral solar panels.

There are some electronic price tag products, wireless keyboards, decorative keychain tags, etc. that could work on solar only, but even those are rare.

e: Forgot digital wristwatches. They seem to work fine.

And it's pretty simple to figure out why it's so for electronic calculators. I had one of these, a modern-ish one though, except that the solar panel was defective and never actually worked. I only noticed after 3 years of use. That's how much the builtin _half-discharged_ coin battery would last... and how useless the solar panel actually is... I would even guess they only put in the solar panel for the look.

You could probably power such a calculator from ambient radiowaves, using a galena crystal...

A lot of basic solar-powered calculators don't have batteries at all. Covering the solar panel will shut it off.

And a lot of cheap calculators don’t even have real solar cells: https://youtu.be/uLTDuGhqE2w

Yeah, what I mean (and has been better put elsewhere) is that the consumption of your average calculator is so low as to be practically negligible (<1mW?), otherwise capable of running for years on a depleted battery. Which is why they may work from such a small solar panel, but at the same time it says nothing about the solar panel itself.

> wireless keyboards

I really like the Logitech K700 solar keyboards, with two caveats:

- In a couple of mine, the included battery seems to have lost the ability to keep a charge well before you would expect (i.e. a year). This is a bit of an annoyance in that it is a rechargable button cell, not your run of the mill AA/AAA sized NIMH/Lithium bit.

- The build quality on these as far as sturdiness/etc isn't great. And if it ever gets 'flexed' too much, you wind up with broken traces internally, leading to issues where the juice doesn't flow one way or another unless you flex it back in the right way.

I love them in the office, but at home they just don't handle the use of clumsy roommates.

>It’s interesting that electronic calculators are basically the only type of devices ever to have successfully powered by integral solar panels.

Because they are ultra-low powered devices. If tiny solar cells can power that kind of device, then it can also be powered through kinetic energy (i.e. user's movement) as well ... Or you could spend $5 and put a standard watch-type battery in there which will last you years. So even there solar panels are a bit gimmicky. But ok, do whatever you like.

On a larger scale, there are a lot of flashing LED road signs or radar speed warning signs that aren't connected to the grid. Instead, they are powered by a small solar panel with a battery for at night. Even simple stop signs on wooden 4x4 posts have these.

At least in my area, the speed warning signs tend to get moved to a different location a couple of times a year, and not having to run any wiring probably makes that significantly easier.

I was going to mention watches! I love my Casio Tough Solar and wore it daily for five years. It never reported a charge level less than 'High'. If it didn't say on the box that it was solar, the only thing I would have noticed is that the battery never seemed to run down.

The solar charging is probably the biggest feature I'm missing in my smartwatch, but at least it has a (low-power, daylight-readable, always-on) transflective screen.

One of the really high-end Garmin watches have solar charging: https://buy.garmin.com/en-US/US/p/641375

According to their docs it increases the battery life by up to 3 days when you're not using the GPS.

Good to know, thanks! The price is a bit more than I can justify at the moment though, you weren't kidding about the high-end part. That's worth more than my car!

Solar powered parking meters seem to be another example.

Many places in my country have no access or reliable access to the grid and kids have to walk many miles to go to school, in this pandemic with the remote schooling this made millions of kids to miss classes or even leave school.

I can think something like this would be very useful for these kids as chargers and solar panels wouldn't last long in the hand of childrens.

> Why do stupid gimmicks like this?

This are very harsh words. Do you have evidence to back the claim that the designer did not do proper research?

Perhaps they had reasons to believe that a self-contained device would survive being handled by children, while an external panel would get lost or broken.

Fewer moving parts? How much power does a low powered laptop need while in transflective mode? How much power does a solar panel produce that’s not facing the Sun?

One could cover the front and back of the screen panel on solar panels this way, if it could create a device that’s mostly independent from a grid or extra gadgets to plug in it could be nice. But yeah, maybe an external little solar array would be more flexible.

>How much power does a solar panel produce that’s not facing the Sun?

Nothing.

>But yeah, maybe an external little solar array would be more flexible.

And those little solar mats are mediocre at best. They just don't work very well. They take forever to charge and require strong direct sunlight. But hey, if you want to use them, go ahead. They are still better than having them built into the device.

At a metal-festival in Northern Germany I was at in 2019, there was a guy with a 1-2m² solar mat. It was enough to charge his phone and play music. Doesn’t seem too horrible.

So it appears modern smartphones have a power consumption of about a Watt (see cousin post). Assuming a transflective display, that laptop could use a similar amount of power. Assuming a 20cm x 30cm charge area and 1000Watt/m2, you need to only capture 1.7% of the energy of the directly incident sunlight [1]. Or assuming your panel has 10% effiency, you need to get 17% of direct sun light light onto the surface. Thats a fair allowance for clouds and weird angles and whatnot.

     [1] 1W / (20cm*30cm*1000 W/m^2)*

If you have non-utilized surface area / volume in the screen part of your laptop, why not put solar panels in there? Yes, their reception might not be optimal due to angling constraints, but if they're light enough, they might still be useful to have. So you don't know for a fact that it's a gimmick.