Follow Slashdot blog updates by subscribing to our blog RSS feed

 


Forgot your password?
Close
typodupeerror
×
Technology

Solar Cells For Laptops? 156

Posted by CmdrTaco from the when-was-the-last-time-you-saw-outside? dept.
P-Weasel hooked us up with linkage to a solar device designed to work with laptops. It's about the right size, and if you happen to ever find yourself outside, this may be just the ticket to circumventing those ridiculously short battery lives on those P3 laptops ;)
This discussion has been archived. No new comments can be posted.

Solar Cells For Laptops? More

Solar Cells For Laptops?

Comments Filter:

  • Re:But I don't WANNA go outside! (Score:1)

    by Anonymous Coward
    I can't think of a single hot technology that is all over the news which would allow you to use your DSL connection outside.

  • Re:Solar Cells (Score:1)

    by Anonymous Coward
    Too bad the solar unit doesn't fold out into a sun shade for the LCD.

  • Re:cell tech (Score:1)

    by Anonymous Coward
    Maybe it would be nice if you could recharge it in the sun, though, even if it took a little bit of time. Then you could play some soccer or climb a tree every couple of hours. If computer geeks actually became big and strong, we'd take over the world.

  • Re:But I don't WANNA go outside! (Score:1)

    by Anonymous Coward
    Solar cell beach tent, nice wireless connection, Babe with suntan oil, life is good.

  • Best info on renewable energy (Score:1)

    by Anonymous Coward

    You all are out of touch with the renewable energy field, these type of solar panels have been around since at least 1992.

    If you want to explore solar and other renewable energy sources and applications, you might want to check out the best magazine to get info about it. http://www.homepower.com/ [homepower.com]

    These folks have the monthly magazine "Home Power" and are pioneers in supplying their magazine in downloadable form on the net.

    They also run their household and publish the magazine entirely "off the grid" with solar and some wind power.

    There are no phone lines to their remote homestead, so they use a long distance radio link for voice AND a data link for the internet.

    They have a bunch of computers, and are ham radio operators as well. They totally qualify as geeks.

    Go Solar...

  • I have a number of small devices, (Palm IIIc, Neo Geo Pocket Color ($60!)) that have reflective TFT LCD displays that look *GREAT* in direct sunlight... plus they draw a whole lot less power!!! my question is why don't laptops use TFT displays that can also switch to backlit for lowlight conditions... so that way when you are outside you draw less power and can actually see the screen...? that combined with the Solar panel should give you indefinite power-life.... so I guess my question really is - is it possible to make an LCD that is dual mode, TFT/Backlit ?

  • Re:Life cycle costs and energy economics (Score:1)

    by Anonymous Coward
    The economics of solar power are held back by the fact that traditional carbon based sources dont need to pay for their waste production (CO2). Carbon trading may alter these economics considerably with the additional cost to coal etc. and the reduced cost to solar from credits for reducing current emmisions. Not all solar cells suffer from increased heat. Titania Cells [sta.com.au]. ANU [anu.edu.au] and Solahart in Australia have worked on using concentrators and cooling systems to reduce costs below that of diesel power systems. You can always make a wind turbine [ata.org.au] for cloudy days.

  • Just strap a car battery on your back! (Score:2)

    by Anonymous Coward
    Laptops will run for hours on these 50 lb things. Of course, FUCKING LAPTOPS NEVER SEEM TO HAVE 12V POWER INPUTS. It's always 15V or 18V. Why are they doing this? It makes it harder to run laptops off of a car. My solution was to install a 300W (don't freak, the inverter won't draw 300W unless it needs to) inverter in my car, then just plug the laptop AC supply into the inverter. But this *must* wast some efficiency.
  • I went outside once. I recommend that you don't bother. For one thing, there's this big bright thing that makes it impossible to see clearly. Secondly, outside there are nasty things like poisonous snakes, sharks, and grizzly bears! You don't want to chance running into those -- just stay inside! Also, you might run the risk of seeing a person you don't know -- someone who might not know how to recompile the Linux kernel. Then you'd have to find something ELSE to talk about. Horrors!
  • Hmm, let's see...

    Maybe you want to code?

    Or write a paper?

    Maybe you can go into civilization occasionally, to purchase software on CD-ROMs?

    I used computers just fine before I ever knew "net access" existed. I could play games, type in programs, and generally do anything I wanted to on my computer.

    Also, I didn't know about *computers* when I lived in the mountains as a child, but when I came back to visit, I'm sure the people in the local commune were very glad they could run their laptop off of solar power. (and yes, there are places where people have phones, but aren't on the grid, too) I know they were using the laptop to teach the kids, and probably for other uses, besides.
    ---
    pb Reply or e-mail; don't vaguely moderate [152.7.41.11].

  • His math is correct. Watts are a measurement of energy flow (joules per second). Multiplying watts by a time period gives you a measurement of regular energy again. In the case of the example laptop battery, that measurement is in watt-hours, a unit that's easier to use in the sort of calculations he's doing. The battery has a total energy of 79WHr. If it takes 3.5 hours to drain it, that gives a constant draw of 22.6W. If the solar panel provides 13.8W, that reduces draw on the battery to 8.8W, greatly extending its runtime. (Yes, this assumes optimum conditions. I think we all realize that solar panels don't work in the dark.)

    No, you can't run an Inspiron 7500 completely on solar power. You can, however, run the laptop for a much longer period of time than the battery alone will give you. You can also recharge the battery while the laptop sits unused. For someone away from a power source for an extended time, solar cells can provide a means to keep a laptop working.


    --Phil (Heck, the thing would be good just for an afternoon coding in the park.)

  • This is not for running your laptop outside! (Score:5)

    by CaseyB ( 1105 ) on Friday April 14, 2000 @09:13AM (#1131742)
    It's not even for saving money on power bills. Where this thing is useful, is for charging batteries in a location where there is NO power available. Think being at a remote cabin, where you leave the charging unit in a sunny window all day, to afford yourself a couple hours of hacking in the afternoon.

    Every discussion involving solar energy always brings out the guys saying how impractical it is to have huge panels strapped to your car / body, and how solar panels don't have enough juice to run a TV all day, and how your device will shut down when a cloud comes by.

    Duh.

    Solar power application today is always about charging batteries, and it's always about low-power requirements in a place where more conventional power is not available.

  • Remember last week's post on IEEE 802.11 antennas to give you AirPort access from miles away? =) Hello, beach! =) You could literally live on the beach while working. Gives a whole new sense to telecommuting. (Ooh, and add a waterproof casing and you could be telecommuting *underwater*!)

    David E. Weekly [weekly.org]

  • i completely agree, for that kind of money, i would likely buy another battery so that i could double the "un-plugged" time. it would likely weigh less than the second battery too. (that being said, it would double the charge time - but how many of us would lug this thing around if charging were time critical to them as well - i can feel the flames coming now...)

  • CaseyB dun said:

    t's not even for saving money on power bills. Where this thing is useful, is for charging batteries in a location where there is NO power available. Think being at a remote cabin, where you leave the charging unit in a sunny window all day, to afford yourself a couple hours of hacking in the afternoon.

    Thanks a ton for bringing this up (I was about to if you didn't)...this isn't really meant for sitting between classes or out on a nice day playing with a laptop (besides, if the day is so nice you're going to brave the Daystar to go out, what the hell are you bringing a laptop along for anyways? ;).

    The perfect application for something like this, IMHO, is for RV travellers (a fair number of folks do actually live in their RVs and go cross country in them--for those who are curious, mail is done by maildrops or forwarding). As it is, a lot of RV catalogues sell solar-panel packages for charging one's batteries during the day in areas where there aren't power hookups (running a generator, especially if someone doesn't have a 34-foot RV or motor coach, can get expensive (especially with today's gas prices); this also works nicely with RVs as most RV equipment uses 12-volt DC or is dual-power anyways--in any case, it certainly saves on using the loud-arse generator :).

    Hell, if I had money to burn, I'd be sore tempted to get one of these setups--as it is, I tend to take two vacations a year in an RV where no external power hookups are available (Bristol, TN during the car races...ok, you can stop giving me that look--it's downright FUNNY to hear the car racers cuss each other out, even if I feel like an old hag seeing all the dot-com adverts all over the place :). A little solar-power array would be right handy for charging batteries for use at night (hell, for that matter, if someone wanted to set up live webcams from car races--the vast majority of superspeedways, including Indy, do allow camping in the infield but don't have facilities for power hookups), because I'd really not like to have to fire up the generator just to run a PC and keep caught up on email :)

    (Then again, RV living would include other specialisations for one's computer...like cell modems or DirectPC service (a positively OBSCENE number of people at car races have DirectTV dishes on their RV's, and a fair number of them tend to be tuned to ESPN...which never made sense to me seeing as they're going to watch the darned race in person ;)...but it IS possible. :)

  • Did you read my post [slashdot.org] as a reply on this same thread? You got the math backwards! Wattage is a measurement PER SECOND, not per hour (the reason being amps is measured per second.. voltage is, of course, instantanious). This is why your electric bill is measured in "kilowatt hours".. not in watts.

    So the math is botched on your post. Also, the ratings for the solar cell are maximum, not nominal. If I take a 120 watt bulb and hold it directly over the solar cell, the rating listed is what you'll get, ie: 13.4. Full sunlight is roughly equivalent.

    Also keep in mind a solar panel isn't like a battery.. it has fluxuating power as the light on it brightens/dims. Maybe if you threw a .1F cap across the leads that would help... but I doubt they did that. This means that if you use this without a battery.. you're not giving your notebook clean power. As any good geek can tell you, insufficient or fluxuating power means corrupt data, unpredictable performance and a slew of other issues. Without a large capacitor or a battery (properly filtered, esp. since some of them have a nasty tendency of *exploding* when too much power goes in) to filter the solar panel's input.. eek.

    But.. that of course assumes the solar panel could supply a reasonable level of power.. which it can't. =)

  • In addition, Amperage is NOT measured per second. Both are time insensitive measures!!

    Ampere/Amperage (Amp) -- Standard unit used to measure electric current; proportional to the quantity of electrons flowing through a conductor past a given point in one second. Amperage is calculated by dividing watts by volts.

    Source: EVVA, glossary [evaa.org].
    Well, they got it mostly right.. except for the "calulated by" part.. and a better example might have been E=I*R.. but what the hell, eh?

    I would say IANAEE (I am not an electrical engineer) but oh wait, I do have a BSEE.

    I really have to wonder about that.. considering you don't even know what a fscking amp of current is...

  • Good thing I got a BSCSE too, eh? ;)

    Most slashdotters got theirs when they opened their user accounts. =) Anyway, I'm still learning electronics, but hey.. I'll be happy to show my ignorance. Only way to learn...

  • Well, barring a tremendous breakthrough in cell tech, you'll never get enough energy. The conversion ratio is in the single-digits.. the rest of the energy is either bled off as heat or reflected. Your current would be ludicriously low inside.. you might get, uhh.. 20 seconds of extra life per hour of use. With 30 flourescent lights shining on it. Which would make the screen impossible to view.

    Nice idea, but completely impractical, especially considering most people use their laptops inside (which is low-lighting conditions, btw). When was the last time you saw a system admin outside? Well... back in '83 we saw one go outside on a sunny day... poor bastard turned to dust, and 'ver since no sysadmin has gone outside.

  • For proof of my above post, the webpage lists "Power Output: 13.8 watts (regulated to proper voltage)". Proper voltage would be 12v, btw. Referring to Intel's PII power consumption charts [intel.com] we can derive that 11.8 watts is used for a typical laptop processor at 1.6v. This excludes things like harddrive, LCD, motherboard, fans, and the other miscellany of what's connected. In short, under ideal conditions this thing STILL won't give you enough power. Calculation of the exact amount of additional time is left as an excercise for the reader...


  • Too bad, then, that I mostly fly between Helsinki and Istanbul - that's as East as you can get in Western Europe, I'm afraid :( (assuming the "Am" refers to "America" - at lest I've never heard of Amtrak.)

    Well, the others can't hold back forever. Meanwhile, I'm happy there's at least one company that does such good service.
  • Soon as I have the $400 extra.

    I'm already ordering my electricity from other side of the country to have it windmilled rather than fissioned. I have a laptop that I use as MP3 player outside, and love to sit out and compute in sunny days - it's just hard, not impossible, to see the screen. Just take a good position. Battery limit of 2 hours is really lame. Lack of net sucks, but I might be able to run ethernet to the roof terrace...

    This is News for Nerds. This is Stuff that matters - for me.

    However, I'm waiting more anxiously to have a Crusoe wearable with wireless Net. And easing the restrictions of computer usage on flights.
  • so you're sitting outside hacking away, then out of the corner of your eye, you spot it...

    CLOUD! OH CRAP!

    >su -
    password:*********
    $shutdown -h no

    RATS! To be truly useful, this solar panel should come with a cloud scanning device, and an audible alert. Or maybe an automatic connection to the same software that UPS devices use.

  • of these [mayberrys.com] - enough power for a notebook, wireless, and more. Solar may be neat but it just can't compete with burning refined dinosaur era hydrocarbons (sunlight energy from long ago locked up in chemical form). Of course, there's only a limited supply [rattlesnake.com] of it left....hmmmm.
  • Hmmm, usually batteries are rated in AmpHours, but I don't see why you can't just * by their rated V and use WattHours - a watthour is a unit of energy (why you electric bill is in WH), and batteries hold only so much energy. Power is energy / unit time. An amp = one coulumb / second. A stich in time saves nine. A nearby batt says 10.8V 4.05 Ah, or about 40Wh - it can crank out 10.8V at 8.1 Amp, 80Watts, for 1/2 hour = 40Wh; or it can pump 10.8V a 2.025Amps, 20Watts, for 2 hours again = 40Wh. Since the laptop can run about 2 hrs on this batt, it's drawing about 2 amps @ 10.8 V or about 20Watts, the solar panel can supply 13 watts so the battery only need to supply 7watts, or .7A at 10V to make up the diff, resulting in increased battery life of 5.7hrs, which is the same result gotten from: 40Wh / 7W = 5.7

    YMMV

  • All I can say is finally! Computer hardware is becoming more and more energy wasteful with each increase in speed/power. At last there's something that can help offset all of that bad engineering...
  • Thank you, how the hell did the first post of this thread get to 5 when it should be -1 Troll?
  • I also have the 7500, and find its battery life to be totally adequate. Long enough to get a bunch of work done on an airplane, do a demo of some kind without having to find a place to plug in. If I need to work for more than 3 hours, finding an outlet has not been a problem.

    (Speaking of problems, the built in "sleep" mode of Win2000 is much less reliable on the 7500 than the third party software for NT4... so I end up being very hesitant to Sleep with Win2K, resulting in greater power usage.)
  • Actually, Linux does support PMU. Check out pmud. It's a daemon that can be used to spin down the hard drive and other PMU functions. The latest release, 0.5-1 is the most recent, but it is buggy on a Wallstreet G3 laptop (Won't wake up from sleep mode). Anyhow, check it out, though. The real problem, though is that Linux doesn't do so well with any spin down of the hard drive, as it wites to disk every few minutes, so much of the functionality is lost. Interesting nonetheless, though.

  • Save power, use PPC! (Score:5)

    by neutrino ( 11215 ) on Friday April 14, 2000 @08:29AM (#1131760)
    Of course you could also use a laptop that doesn't suck down the power. Why plop an x86 cpu into a laptop? Ever notice that most x86 desktops have enormous fans and heat sinks on them? That heat has to come from somewhere. Get an Apple Powerbook. PPC chips don't drain a battery like a PII does. Plus, then you could join us LinuxPPC users out here on the fringe! We don't need no stinking binaries!

    Posted on a Powerbook G3 running LinuxPPC2000

  • Actually, the first time I saw a solar powered laptop, it was some guy's PowerBook 160. He also had a secondary battery that was same area as the powerbook and about a 1/2 thick. Apparently he would get enough sun to actually charge the battery somedays. (Of course the total weight of this setup was probably 15#, but he was off the grid.)

    That had to be at least 10 years ago. I would have to think that a solar powered G3 PowerBook would be the best way to sit in the park and 'work' all day.
    --
  • Take a look at the bottom of the page:

    "Some of these projects include supplying aid to refugees in Eritrea, searching for meteorites in Antarctica, studying the forests of Borneo, cataloging the languages of Vanuatu, and teaching school kids remotely from Central America..."

    So, for these sorts of applications, $395 for 13.8 watts isn't all that bad. You have a small market, consisting of customers who have few other choices (Besides lugging around a portable generator) that are willing to spend lots of money--and I'll bet the startup costs for this business are tiny (Compared to another company with a similar business model, Iridium).
  • Too true. Add to this the fact that LCD screens are just horrible to look at in sun-light (glare) and it's a solution in search of a problem.

    Nice idea for Crusoe-powered web-pads for use by students at college campuses, but then again... It's not convenient to sit in direct sunlight to even read a book. A shady spot, under a tree is much better, and, well.. there goes the solar power idea.

    Well, a revolutionarily efficient solar-panel could be made into roofing material. That's about as close as they'll get to powering my PC.
  • first a way to SEE a laptop screen outside in the sun. It might be fun for people with Gameboys or Palm Pilots but not laptops.
  • I've got one on my desk right now. I just got it from someone who didn't want to support a Sun anymore, and I won't have any time to familiarize myself with it for a few months... but it seems to run fine indoors.

    I hear it can give you a nasty burn, but the screen isn't all that bright. What's the deal? Is it due to CRT X-ray emissions? (Mommy always warned us not to sit to close to the TV) Probably -- my friends always seem to have them when they come back from underdeveloped places, like St. Kitts or Mexico. I imagine they have a lot of older surplus monitors in those places.

    My Sun does seem to run as hot as everyone says.

    __________

  • Life cycle costs and energy economics (Score:5)

    by ForteBravo ( 15741 ) on Friday April 14, 2000 @10:11AM (#1131766) Homepage
    Your life cycle cost calculation is a step in the right direction -- it does show exactly how cost-ineffective these panels are in relation to wall power. But I'd like to take issue with a few of your points.

    First, if you are comparing to wall power, then these are obviously a bad deal. Distributed energy is always a bad deal compared to existing wall power. That's because the utility has already made all the capital investments for you, and they get the best deals on long-term financing -- it's hard for an individual to do better, even with all those utility investments in nuclear.

    But these are an outstanding deal if you live off-grid. They are convenient to move around, they have a cord so you can keep your laptop in the shade and the cells in the sun. Unfortunately, the level of ambient light even in the shade is too high to comfortably view a laptop screen. It takes some getting used to, especially during the middle of a sunny day.

    Second, regarding solar power plants. $0.56/kWh is not "just on the edge" (edge = $0.03/kWh) and photovoltaics are the least likely technology to be used in a commercial powerplant, barring commercialization of that Australian guy's silicon wafer manufacturing improvements. Yes, it is true that efficiency and output are directly related to the amount of sunlight shining on the panels. However, they are inversely related to the temperature of the panel. The hotter they get, the worse they work.

    I'm afraid you are also taking a bunch of disparate facts about the energy industry and taking them out of context here. The reason prices hit $6000/MWh several years ago was because of market speculation and a series of shady deals. It had nothing to do with the real cost of producing energy.

    I am not trying to rain on anyone's parade, as I am in fact a die-hard renewables supporter -- I worked in the energy industry and I know how much we need cleaner technology. But there are many other emerging technologies which will change the industry drastically, much more so than photovoltaics. For instance, fuel cells - technology with a chance. Prototypes of fuel-cell powered laptops and cell phones exist, and will soon allow you to run your laptop 28 hours without "recharging". Not only that, but you'll probably able to carry around a couple of very small canisters of hydrogen or other fuel much more easily than toting batteries.

    Now that is mobile computing.

    ----------

  • It's like a giant, round fullbright pixel in the sky.
  • Apple's PowerBook 1400 (released in 1996) has a slide-out panel on the top, called a BookCover. You can put in different cardboard cutouts, and some companies made BookCovers with pockets for disks and pens and such.

    A few years ago, a company (name escapes me)sold a solar panel BookCover for the 1400. It wouldn't entirely power a 1400, but you could extend battery life a bit. You could also recharge the internal battery in about 6 hours (the battery gave about 2 hours of run time, if you were lucky). I never picked one up, and I can't find much about it on the WWW any more.

    -jon

  • It would be nice if what you said was true, but its not. pmud is for bronze and earlier powerbooks only. The new firewire powerbook's PMU is unsupported. I think the iBook's PMU is also unsupported, but I am not sure.

    To help out the spindown problem, try mounting your partitions noatime. This prevents it from writing to disk every time it accesses any page (even though the page is in cache). This usually lets the system spin down the hard drive for enough time to be worthwhile.
  • My 500Mhz g3 powerbook gets about 7 hours with both batteries in. Which is excellent considering linux doesn't support the PMU, so the hard drive is always on, the backlight is always on FULL BRIGHTNESS and the sound/ethernet/modem is always on.

    Of course, I can't use it on my lap, because like a PIII laptop, it gets pretty hot as you run it.

    rc5 (i know, i know) puts it about even with a desktop PIII-650. Which is especially impressive considering that a mobile PIII is slower than a desktop PIII.

    I don't know if the price difference is worth it for apple desktop hardware, but for laptops, apple is the only way to go.
  • I don't know about you guys, but it sounds great for anyone with a sailboat, a cottage by a lake, etc. Slap your laptop in a pelican case and take it into the wilderness for two weeks. Use it an hour a day or so and let it recharge the rest of the time. Lots of cool uses - if it were about $100 cheaper I think I'd be grabbing one right now!
  • The scary part is that he might not be joking. ;)
  • Now I just need to hook one of these up to my cloud generator and my plans for world domination will be complete!

    Kevin Fox
  • I'm not very excited about Solar Panels.

    Remember those calculators with the solar panels that were so hip in the 90's? Those sucked! You had to angle them just so for them to work.

    Fuel cells, on the other hand, rock. I mean, you get some hydrogen from algae and your laptop runs for weeks without a recharge.

    Wake me up when that happens.

    Lisa
    [grrl.org]

  • Does anybody remember comapaq's method of obtaining energy from each keystroke on the keyboard? Any insights on what happened to that?
  • Let's see if we can make an educated estimate as to how long it would take to power a standard-type laptop battery.

    The solar constant at the location of the earth (luminosity of sun / (4 pi distance_from_sun_to_earth^2) ) is 1370 w / m^2. Let's be generous, assume the collecting area is 1 m^2. Let's also call things roughly. Per hour, that translates into (3600 s) (1 KW /m^2) 1 m^2 ~4 10^6 J. Let's say that a solar cell can have an efficiency of about 1%. That translates into 4 10^4 J = 40 KJ of energy.

    How much energy does a typical battery store? State of the art chemical batteries typically have energy densities of 1 KWh / kg, or roughly 10^6 J/ kg, as above. This means that to charge a 1 kg battery, roughly 100 hours are required.

    Even if the efficiency were as high as 10%, about 10 hours would be required to charge. Hence, it seems that the concept is good, but it would take at least a full day in sunlight to charge up a laptop battery. Not very practical, considering that the very idea of a laptop is to be mobile...

  • do you know where I might find this particular location of hell? I will mount a rescue mission, to get the laptop back. The *real* people scare me to much to get it back to you, I'll just bring it back to my place.
  • BUT, something like the IBM Z50 workpad, modded to run Linux, would run pretty much INDEFINATELY on that solar cell.

    Indefinately untill night, I suppose.

  • It's not convenient to sit in direct sunlight to even read a book. A shady spot, under a tree is much better, and, well.. there goes the solar power idea.

    So sit under a tree... and get a long cord ;).

    You don't have to glue the cells to the laptop.

    - StaticLimit
  • Good point, you've pretty well got me on that one.

    The point really should have been that power (work per unit time) has no relevence in this context unless we look at it being applied for a length of time. Energy is the important consideration as it indicates the amount of work that can be done. Your assersion that I got the calculations backward because wattage is measured per second wasn't wrong because wattage isn't measured per second, but because the time units associated with wattage, a measure of power, wasn't really at issue because the calculations center around energy (watt*hours, watt*seconds, megawatt*picosecond, or whatever), and therefore arguing about the time units watts are measured in was not relevant.

    Good thing I got a BSCSE too, eh? ;)

    Thanks for the review lesson...
    - StaticLimit
  • Wattage is NOT measured per second. It's a measure of POWER as in P=IV where I is current in Amps and V is voltage in... volts.

    In addition, Amperage is NOT measured per second. Both are time insensitive measures!!

    Dell lists their battery life in Watt * Hours and therefore, dividing X Watt * Hours by Y Watts results in X/Y Hours.

    In addition, I specifically stated in my assumtions that the notebook has the battery IN at all times. It would be crazy not to have the battery in, as you mentioned above, which is why I never suggested you take it out!

    Take some physics, take some circuits, and re-read my post (noting the battery, and my comment at the end that the calculations are based on the 13.8 Watt figure from the company and the lower end of Dell's estimate on battery life!!)

    I would say IANAEE (I am not an electrical engineer) but oh wait, I do have a BSEE. Even if you discount the figures significantly for fluxuation in sunlight levels and optimism on Dell's part, your figure:

    you might get, uhh.. 20 seconds of extra life per hour of use. With 30 flourescent lights shining on it.

    is patently ridiculous.

    - StaticLimit

  • Re:cell tech (Score:5)

    by StaticLimit ( 26017 ) on Friday April 14, 2000 @08:48AM (#1131782) Homepage
    Let's note the sales lit. on their site first:

    Assists the internal battery of your portable computer adding many hours to your normal run time from a charged internal battery2 (runs many computers, not just extends).

    Recharges the internal battery of your computer or device. Also capable of running an external charger for your batteries3.

    Dell's Inspiron 7500 (top of the line notebook) runs 3.5-4 hours on a 79WHr battery, so it draws approximately (79 / 3.5 =) 22W. Not too bad. The solar charger as noted provides 13.8W which should be more than enough to justify their claims above. It should extend the life to about 9.5 hours, a significant increase.

    79 / (22 - 13.8) = 9.6

    In addition, full recharge of the battery should take about (79 / 13.8 =) about 5.72 hours. That's a full recharge... Every hour of use (assisted with the solar panel) will take ((22-13.8) / 13.8 or 5.72 / 9.5) = .59 hours of charging with no use.

    Assuming Dell's estimates aren't too low and theirs aren't too high, and the sun is shining... I'd say this is a good deal.

    - StaticLimit
  • You want to get energy out of changing water to water vapor? I don't think so, unless cooling your canvas-covered laptop is your goal.

    But you might remember recent news about an alcohol fuel cell [slashdot.org] for portable devices [slashdot.org].

  • You just needed to aim a carbon arc spotlight at each of your cars indoors...
  • Just charge up your cellphone also...
  • It's not so much what you have as how you use it [scotland.net].
  • Except oil is from rocks [cornell.edu] not dinosaurs. It's just floating up from below [space.com] and getting trapped at various depths. Not only is it not nearly as limited as previously thought, but if we run low we could go get an asteroid [explorezone.com] full of carbon [scibernet.com] and make more [permanent.com]...
  • Read again. He's not digging test wells around the world with his little shovel, others are testing and finding oil in "impossible" places. And just this week was the announcement of researchers confirming that methane can be produced by oil-eating bacteria [sciencedaily.com] without requiring sulfur, which helps explain methane deposits in more places than previously thought, and that methane did not require any fossil decomposition process.

  • Re:Ahhh (Score:4)

    by rcw-work ( 30090 ) on Friday April 14, 2000 @11:46AM (#1131789)
    Out side the door I seen people I knew from when I was younger. They starting talking to me, and poking me and making this awful sounds (Bob said it was probably laughter), confused and dazed I retreated back into my room to review the sisuation with Bob.

    The laughter thing has an easy fix - you have to put these things called "clothes" over yourself. Bob probably just assumed you already had them on.

  • These folks are just trying to unload stock after their solar-powered flashlight business tanked.

    Next we'll see them unloading the flashlights as a means to light the solar panel.

  • I had a solar cell that fit into the cover of my Powerbook 1400. Which sucked, since who points the lid of a laptop at the sun while you're using it? But it's been around a while
  • No, it just'll work well for them. Why not let the batteries fill up while your not using the laptop?
  • Static's got it right, with but one caveat (and I don't have the numbers here): Pumping 1 AH into a battery will give you somewhat less than 1 AH out of it. Efficiencies have come a long way with the NiMH & LiIon technologies, but I'm afraid 100% is one of those not-quite-reachable goals.
  • it was way back in the dark ages of 1997, i got the solar panel from a local eco-guru, who had some small models, which we then outfitted with the right jack, and tested to make sure had the right voltage and a/c.

    i cannot stress just how wicked it was to a) not have to worry about having the right plugs b) not having to worry about having electricity c) rocking the funky joint!

    damn it was an awesome year 8)
  • Ahhh! I'm melting. Melting! Ahhh!

    BTW, I have denim curtains to keep the sunlight out of my room. Really.

    Ryan
  • But plenty expensive, too. Look into solar panels for RV's - many of these are quite large, and can be adapted easily. You will need a large voltage regulator and a battery bank as well - and if you are planning on running 110VAC, an inverter (many people just buy 12 or 24 volt appliances, instead). You can easily spend several 10's of thousands of dollars on a system.

    Look into wind power options as well (if you have an ample breeze blowing). If you live near the border of Mexico (near a border town), sometimes resellers of solar solutions hang out on the US side (esp if there are RV camps near the border town).

    Building a solar panel for heating water is almost trivial - a bit of copper pipe, some plywood and two by foors, and black paint (plus a sheet of glass) is about all you need. You can build a pretty good system to tie into your home heating system for less than $500 (and remember, you might be able to take a tax break as well).

    Final note - it is possible to build a house and COOL it using a passive solar solution. The trick is the house has a large chimney which is heated by the sun. As the hot air rises, it draws in cooler air through the windows, or through vents with water evap pads (similar to a swamp cooler). Not great for places like Lousianna, but for desert areas without too much humidity, it is almost free cooling.
  • Hear! Hear! Wish I had moderator points today...
    I need to get a solar, uh, expert out to my place sometime to do some readings- I think there are too many trees in the way for a good solar array on my roof (though- never such a thing as too many trees! ;). If it is feasible, it will be installed and will charge a battery specifically for running the well pump. That only turns on about four times a day, and for about 5 minutes. Not sure of the Kw usage, but surely enough to run off a constantly recharged battery. The battery will ALSO run the sump pump when its needed- which failed during Floyd when electricity was knocked out by trees and our basement flooded (we were out of state).
    Solar power definitely has it's usefulness, but isn't a cure-all....yet.
    Time to get outta here and go hug a tree.
  • for lack of a reason to use it outside. No net no fun.
  • I've got an expedition model of this series that I purchased a few months ago. A bit pricey (around $400+ i think) and I haven't quite got it to go quite to the full rated spec of around 20 Watts, but the cell is supposed to be more efficient at higher ambient temperatures.

    With passive resistive loads I've seen as high as 16-17W (but on cold days as low as 10-13W!), but keep in mind if you run it through an inverter you are going to get some loss probably 2-3W. To bypass this problem I bought a 50 Watt zener diode at the rated voltage of the DC input (around 16V for my laptop). (Cost around $12 versus $75-$100 for an invertor). In my research I came across this site [earthlink.net] from which I learned that solar cells act like current sources, which is ideal for a zener diode. The diode essentially syphons off all the extra current your laptop uses, and since it is placed in parallel with your laptop it doesn't draw any power that your laptop can use. The zener also regulates the voltage fairly well. The 50W rating is necessary because there is no series limiting resistor and thus the zener should be able to sink twice the rated capacity of the solar panel (to be on the safe side, especially if you don't have a heat sink ;)

    I also played around with the idea of some kind of mirrors to focus more sunlight on the panel, but then I figured that kind cuts down on the portability of the system. The panel itself is fairly lightweight, around 3 pounds I think, same as my laptop :-)
  • Amen. I don't care if a CPU is 5% faster than the previous generation, because with the 5% comes an equivalent or greater increase in power consumption and heat output. The laptop industry may be the savior of us all, and solar cells are a step in the right direction.
  • It's not convenient to sit in direct sunlight to even read a book. A shady spot, under a tree is much better, and, well.. there goes the solar power idea.

    The cord is 10' feet long (about 3m) so you just have to find spot that is within that distance of a sunny spot, whcih except for heavily wooded areas, shouldn't be a problem.

    I suppose if you wanted you could even mount the panel in or outside a window and use the notebook inside, but who wants to be inside.

    Also, it can be used to charge your battery so you can take back into the shade once it is done charging.

  • You call that cheap?

    this [damark.com] is half the price for slightly more wattage (15 vs 13.8).

  • *I* use a laptop outdoors...
    I like the big blue room, and a laptop lets me be in it more. Granted, most of the time has been spent right outside my house with ethernet and power strung through the window, but is nice to get some sun and fresh air anyway...
    I bought a p-120 laptop when I was in college (very useful, that), and still find is powerful enough for my uses. Sure, it takes a little longer to compile my projects then my desktop, but it really isn't all that bad.
    Besides, I often just use it as an x terminal and do all the heavy processing on my desktop.
    Now, whenever I can afford wireless networking and a few spare batteries things will be much better. This solar power source looks like it has enough juice to extend battery life a little anyway, which may serve to extend my reach from home a little further. A welcome development in my book, especially because my house backs right up to a nice park ;-)
  • Apple hardware is way expensive.

    I wish someone else would make PowerPC stuff. What the hell are IBM and Motorola doing with all their chips? Are they just selling them to Apple?

    There's got to be a better solution here. If I have to design the motherboard and CPU myself, it could take decades. :)
  • Ive never been outside... What's it like?
  • You are right, newer power hungry laptops won't work off these solar cell puppies.

    BUT, something like the IBM Z50 workpad, modded to run Linux, would run pretty much INDEFINATELY on that solar cell. I actually thought about that, making a unit (calling for engineering samples? 8-) and wiring together a folding panel...

    As for sunlight readability, nobody said anything about the solar cell and the laptop at the same spot. Just sit under the tree, and run a short cable out to the solar panel in the sun. Voila. Problem solved... 8-)

    -=- SiKnight
  • Check out http://www.mhtx.com ...these guys are making fuel cells for small apps like cell phones etc. They and others will have fc for computers within a yr or two.
  • what happens when you burn hydrogen H20... what do hydrogen fuel cells react the hydrogen with, oxygen, so once again you get water, the thing is instead of putting in water, you put in hydrogen... the hydrogen is generally seperated from the water elsewhere

  • Are you sure you need 15V to run your laptop? I've got an old Toshiba Libretto 50 which runs fine on 12V but only after you send it a brief jolt of 15V to convince the power management hardware that there actually is an external power source connected. To get the 12 V I use cheap sealed lead-acid camcorder batteries (Radio Shack 22-187 or equivalent), which I can get for as little as $25 each, and which run my Libretto for about three or four hours or so on one charge. I got the idea and plans from Xin Feng's web page [fixup.net], thanks Dr. Feng! Certainly a little doodad with a couple of 9V batteries will be easier to handle than a big inverter plus your laptop's AC adapter, and you can carry a camcorder battery or two around with you.

    My Libretto runs Linux too; in fact it's a bit underpowered for them new-fangled power-suckin MS OSes, but Linux just sprints along on it, though it's a bit of a trick getting it installed because of the weird external floppy drive that doesn't work with Linux boot discs. Basically my trick was to yank the HD and get an adapter so I could hook up the Libretto's 2.5" hard drive to a normal 40-pin IDE connector like you see in a desktop machine.

    Yours WDK - WKiernan@concentric.net

  • Yes, I know... I still think that panels have a future in commercial power. It doesn't really matter how inefficient it is if the panel gets cheap enough. The real cost has come down by a factor of 20 in about as many years, there's no reason to think that it won't come down another several factors. Efficiency is going up, albeit only on the bleeding-edge expensive panels.

    Everything gets cheaper if it's manufactured enough (Econometricians: please don't from my stating it backwards).

    Peak load power is still pretty expensive. Last year KCPL lost two power plants to explosions and had to pay $2200/MWH. Ouch.

    I was thinking that it could be practical to install solar farms as sunshades for cooling ponds for steam power plants. The grid is local, the land is in use already and the shading should help the efficiency of the ponds. They could even have heat sinks into the pond for cooling.

    But we've divered far afield. I agree with you wholeheartedly, esp. about fuel cell "batteries" for laptops, I really want one badly...

    But first, I should get a laptop. =-]
  • Suppose you worked outside all of the time for the expected life of the system, 20 years. Suppose that once you figure in the number of hours of daylight times the 'directness' of the sunlight cutting into the efficiency, you'd get about 7 hours of 13.8 watts. Then you'd get about 700kWH out of the pack over its lifetime. At $395, that works out to only $0.56/kWH. Not bad, only about 10 times the cost of plugging into a wall.

    I figure these things are 2 panels of about 9" by 12" or about .15 m^2. The incident solar power constant is about 700 watts/m^2 at noon. At 13.8 watts, these things come out to about 12% efficient. Also not bad.

    So, obviously, these things aren't for everybody. But it is a good thing that prices have come down and they're manufacturing the cells more durably than before.

    Maybe in a few years (with the power grid peak prices hitting $6000/MWH recently), someone will decide to build a solar panel power plant. It has the advantage of having its peak output at the same time as the air conditioners are using the most energy. It's just on the edge of being a practical energy source at $0.56/kWH. We'd just need to make lots and lots (and lots) of cells...
  • I saw a program on PBS about solar panels, they are making photovoltaic (sp?) roofing shingles. (Only available in Japan at the time I saw the program.) They are supposed to last 100 years, the only problem is the $150,000+ that it will cost you to roof your house with them... I have my doubts that they would pay for themselves in their 100 year lifespan. (Lets see, I pay about $80/month for electricity [$150,000/$80]/12=156.25 years to ROI, and that's just the shingles, you wanna add a storage system to your house?? That could make the shingles themselves seem cheap...)
  • I'll bet it woun't be long until this is a screen for your LCD.....<br><br>

    It is perfect if you have a bit of shade that you can hide the LCD under. ;) ~ion
  • you have too much time on you hands
  • http://jcwhitney.com/product.jhtml?CATI D=5460 [jcwhitney.com]
    12.75V but should be ok $129

  • problem (Score:3)

    by Ukab the Great ( 87152 ) on Friday April 14, 2000 @09:48AM (#1131817)
    But what do you do if the sun explodes? What are you going to do with your solar panels then?
  • If you built this solar panel AS A SCREEN SHADE, then you could get your power & be able to see your screen (and keep other people from seeing it) at the same time!

    Actually, although this thing won't provide enough power to use your laptop at full throttle all the time, I could see where you could use it to slow DOWN how fast your laptop uses power, and leave it charging your laptop when you're not using it.

    It's too expensive for me though - if it were around ~$50 US, it'd be nice to have - but not at $395 US (over a 1/3rd of a typical laptop price!)

  • They've been selling solar cells for laptops for a long time -- this is nothing new, but still interesting to look at for those didn't know these things existed.

    MrSolar [mrsolar.com] also has some laptop solar panels [mrsolar.com] available -- kind of pricey, and he was a bit of a Y2k nut. Wanted to boost his sales, I guess.

    Patrick

  • I hate having to correct people, but StaticLimit was right. One watt is one joule per second. It measures instantaneous power. Watt-hours are simply watt multiplied through by unit of time relavent to this application, multiplied by an appropriate conversion factor (3600s/hr). Thus, one watt-hour is 3600 joules.

    Now, look at his math. 79W-hr*3600s =2.84e5J. Okay, that's stored energy. Looks good so far.

    2.84e5J / 3.5hr = 8.12e4 J/hr. Hmm, non-standard unit. Let's convert those hours into seconds.

    8.12e4 J/hr / 3600s = 22.6 J/s. Why looky here! Joules per second! That, my friend, is out long-lost Watt.

  • Their own web page emphasizes recharging rather than running portable devices. It's still kind of cool, and could be usefull in limited situations.

  • Just think - now in the summer we can get outside, use that wireless LAN to hookup to the server, enjoy the fresh air, and ... yes ... if you position those solar cells under you chin like so ... you can even get an even tan!

    Cheers,

    Toby Haynes

  • My subject line works on so many levels.

    In fact I already thought about placing multiple solar batteries on the roof of my house to save on at least a portion of my Hydro bill.
    Has anyone any experience with this? Are there other products for that use or do you have to build something of your own. I don't really want to have 20 P-Weasel bags on my roof!

  • Ahhh (Score:5)

    by jbarnett ( 127033 ) on Friday April 14, 2000 @09:07AM (#1131848) Homepage
    I got one of those, bought a new laptop also, full stack P3. I got it on monday, plugged it in and NOTHING worked. I called tech support and they said

    "Sir, the unit must be in direct sunlight for it to work"

    "Excuse me?"

    "Sir, you must take the unit outside with you, it needs to be exposed to direct sun light for it to harvest enough engry for it to power you laptop"

    "uh, ok"

    At this point I had no idea what he was talking about, but at the risk of sounding dumb I replied

    "right-o boy, thanks it is working now"

    Having no idea what 'sunlight' was, or where to download a copy, I did a search on http://www.google.com and came up with a few links.

    My finds indicate that "direct sunlight" is "light" that is not produced by a light bulb, but rather an object that is referered to as the "sun". Easy enough I though, I take the unit and my laptop into the server room, and place the unit directly under a Sparc Station 20. Giving it 20 minutes (has to charge) the laptop still was not receiving power from the unit. Thinking quickly, a SS20 these days isn't /that/ powerful.

    Pushing pass ethernet cords I set the unit directly under an a cluster of Ultra 10's. "That should do it" I proudly thought to my self, waiting, waiting, I was sure it was going to work this time. After 30 minutes I re-contacted tech support.

    "Sir, *THE* SUN, you know, *OUTSIDE*."

    Ah, I felt really stupid at this point. I decided to contact Sun tech support and see if it was a defect in the rays their servers where giving out. I relayed what the other tech support told me to Sun's kernel group, they to where making refereres to the "OUTSIDE". Hanging up before they thought I was stupid.

    Loading up Netscape on my workstaton, I typed in http://www.theoutside.com and came across a punk band. After searching their site for 4 hours staight I still didn't see any "SUN"

    *sigh*

    Really depessed I started talking about my problem with this unit on IRC. A helpfully person by the name of "Bob76" on #bob_channel enlightened me to a whole other world. Not methophically mind you, but really a WHOLE OTHER WORLD. See said that someone in my room there would be an object called a "door" that was either made of wood or metal. Searching around and relaying my finds to "Bob76" I finally found the "door" after many failed attempts.

    "Bob76" insturcted me to go out the door. Bob even helped me Crack the security methods on this certain door (I feel elite! :) Out side the door I seen people I knew from when I was younger. They starting talking to me, and poking me and making this awful sounds (Bob said it was probably laughter), confused and dazed I retreated back into my room to review the sisuation with Bob.

    He said these strange cretures where *REAL* "people" and that this was known as "*real life*". Bob started getting weird with this topic, about people and life, really deep, but creepy.

    quickly changing the topic, bob insturcted me, that their would be yet ANOTHER door after the first one, and maybe something called a "hall way" of other rooms with strange names like "kicthen" or "living room". Bob advised me to quickly open the door, keep my head down and quickly find the other door. He said this second door should take me outside.

    Packing up the solar unit and the laptop, I thanked bob and decided to go for it.

    I quickly opened the other door and these people started using strange launge like "hi" and "how are you", I keep my head down and didn't say anything like bob instructed, I quickly moved in and out of this maze of other rooms and "halls" and finally came upon the second door.

    I started to sweet and time seem to stand stil, I reached out and opened the door. tossed the solar unit and laptop out on what appeared to be "green carpet, but real dirty" I push out and I knew I was outside.

    My eyes started to burn from this intense light, and my skin started to burn, the light was really intense and bright, pushing on me, burning me, making me really disilluated and confused. I feel to the ground and all I could see was WHITE, burning my eyes, face hands, arms

    I managed to find my way back into the second door and quickly close it. confused, but a lot better, I made my way back to my workstation, making sure I closed and re-enabled the security fearture on the first door I orginally found.

    I felt really terriable for days after the experince, my laptop and the solar unit is still traped in this hell know to bob as the "outside". I think Bob is the devil.

    I hacked out 20 thousands lines of ASM code, porting the Linux kernel to a embedded device I found in my alarm clock, after that I felt a lot better. It was only a 2-bit cpu with 32 byets of main memory, but quickly rewiring it, and using some ram I pulled from a CD-players LCD I was able to get a nice port of kernel 2.2.13 to it.

    Anyways, I still don't know how I am going to get my laptop back, hell can keep it's "solar panel", I think it was sent here as a temptation from bob (the devil) to lure me out into hell ("the outside").

  • Real Goods ( www.realgoods.com [realgoods.com]) has a variety of solar panels, including one which powers a laptop [realgoods.com], so is comparable to the unit featured in the above story. Price is $369.00
  • Maybe they should work on a wind powered charger for as much hot air that blows though corporate these days.
  • Of course a solar panel isn't much use in an environment in which the Sun can sometimes be considered a myth used to inspire hope in the general populous. Though I guess if it opened out to the size of a football pitch it might manage to get enough power from the ambient light.

    I used to live in Scotland and am now in Southern England so I guess I'm moving in the correct direction (but my feet may get wet if I continue).

  • But I don't WANNA go outside! (Score:4)

    by Saint Aardvark ( 159009 ) on Friday April 14, 2000 @08:23AM (#1131873) Homepage Journal
    ...and just how the hell is my DSL connection supposed to reach down to the beach? Huh?

  • This would be great if I could actually see my screen outside in the daylight.
  • Real Goods [realgoods.com] and Jade Mountain [jademountain.com], among others, have been selling these for several years now, for a wide range of laptops.
  • Solar cells recharging... my power is returning... BIIIIIIRRRD MAAAAAAN!

Slashdot Top Deals

The most difficult thing in the world is to know how to do a thing and to watch someone else doing it wrong, without commenting. -- T.H. White

Close