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Earth Power

Portable Solar Power For Portable Hardware? 262

Posted by kdawson
from the try-chlorophyll dept.
Tjeerd writes "Because the 'green revolution' is accelerating, I felt it was time to get involved. Last week I started with buying a portable solar energy charger for my mobile phone. But soon I was thinking of also recharging my Asus Eee netbook with a portable solar energy recharger. I found things like the Portable Power Pack, Foldable Solar Chargers, and the Solar Gorilla. The Solar Gorilla looks quite interesting and might be able to recharge my netbook and fits nicely in a rucksack. But I would like some real-life feedback. If you have experience with these or other portable solar devices, what has worked for you?"
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Portable Solar Power For Portable Hardware?

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  • by Anonymous Coward on Tuesday November 04, 2008 @03:01AM (#25623383)

    "Because the 'green revolution' is accelerating, I felt it was time to get involved."

    Have another sip of cool-aid. Everybody is doing it.

    Not saying that being more green is bad - just your reasons to do it.

    And I'll quote the famous wise guy Kermit.

    It isn't easy being green.

    • by couchslug (175151)

      "It isn't easy being green."

      Evidently not!

      http://www.sadkermit.com/ [sadkermit.com]

    • Re: (Score:3, Interesting)

      by b4upoo (166390)

      Those products are a rip off. The price for what you are getting is beyond all reason. Check our solar cell products and make your own connectors to suit yourself. You should be spending about 10% of what these jokers are asking.

  • Plants (Score:5, Funny)

    by Smivs (1197859) <smivs@smivsonline.co.uk> on Tuesday November 04, 2008 @03:02AM (#25623387) Homepage Journal

    I have been using solar energy to 'recharge' my houseplants for years.

    • Re: (Score:3, Insightful)

      by theaveng (1243528)

      And if you use ethanol in your car, you are using solar power. But as for solar cells for your laptop? It creates MORE pollution, from the manufacturing process of creating the cells, then simply using a few pennies from your local coal electric plant. You make the air pollution worse, not better.

      The only time solar cells will reduce pollution is if you use them for mega-kilowatt devices, like heating units or air conditioners for your whole house. Only then do you overcome the pollution contribution

      • Re: (Score:3, Informative)

        by ShieldW0lf (601553)
        Try an onion [youtube.com]
      • by gurps_npc (621217)
        Many forms (not all) of ethanol create more pollution than they save. The best form is that used in Brazil which is created from agricultural waste, not the US type where they grow corn just to make ethanol. As for solar, you are using outdated, false information that counts things twice. I.E. they did things like say "x amount of pollution for creating the chip and y for creating the silicon in the chip when x included y. Solar Panels, if used for their entire estimated lifespan make air pollution bet
      • And if you use ethanol in your car, you are using solar power. But as for solar cells for your laptop? It creates MORE pollution, from the manufacturing process of creating the cells, then simply using a few pennies from your local coal electric plant. You make the air pollution worse, not better.

        I've always wondered about this. How exactly do they measure the amount of pollution a given product creates through its lifecycle, from resource gathering to manufacturing to transportation to daily use to trashing/recycling it?

        And is there any way for the average consumer to do gauge the same thing before buying that product? Say, for comparing the Prius to a high-MPG gasoline car or a Freeplay light versus a propane lantern?

    • Re: (Score:3, Funny)

      by michrech (468134)

      I like a darker climate, so I furnished my house with plants that like "less light". ;)

  • by BadAnalogyGuy (945258) <BadAnalogyGuy@gmail.com> on Tuesday November 04, 2008 @03:07AM (#25623399)

    Solar has a lot going for it as an alternative power supply for portable items. The problem is that many of those items aren't exposed to sunlight for enough time to actually charge the reserves.

    That's why I use a hand-crank as my primary source of alternative power to my portable items. Especially in the winter time when sunlight is at a minimum, good old elbow grease is always there.

    • by Sarten-X (1102295) on Tuesday November 04, 2008 @03:13AM (#25623427) Homepage

      Until you're out hiking somewhere, and you lose the use of your arms in a terrible accident involving a pine tree, a squirrel, and a toothpick. Of course, your boots are still tied on, so using feet to crank isn't an option either.

      Where is your precious elbow grease now, huh?

      Wait a second... this is slashdot... "hiking" consists of going to the door to sign for the latest shipment of your chosen caffeine source...

      • by sumdumass (711423) on Tuesday November 04, 2008 @03:59AM (#25623613) Journal

        Hey, wait a minute. I found myself in that exact same situation last year. Did you read my article in "outdoor geek's playhouse"?

        Well, if you did, you would have realized that the answer was using the candy wrappers to fashion a sail on the cranks with your tongue then role over and fart while moving your ass from side to side to turn the crank. It helps if you ate microwave burritos before the hike. You then think about using the force when you use your tongue to dial 911 and wait for the ranger to show up talking about putting on his robe and wizard hat.

        • Re: (Score:2, Insightful)

          by Anonymous Coward

          wait for the ranger to show up talking about putting on his robe and wizard hat.

          Pfft, you almost had me, but then you blew it. What self-respecting ranger is going to take levels in wizard?

      • by RuBLed (995686)

        Until you're out hiking somewhere, and you lose the use of your arms in a terrible accident involving a pine tree, a squirrel, and a toothpick.

        You forgot the "and you met the Disco Bear" part.

      • by wvmarle (1070040)
        Makes one wonder why a /. user would want a mobile recharging device in the first place.
    • by rusl (1255318) on Tuesday November 04, 2008 @03:57AM (#25623603)
      Are you serious about hand cranks?

      I'm a cyclist and I sure would be. Human power is seriously overlooked. Using your much stronger leg would be easier.

      I have a cheap hand crank flashlight that has a plugin supposedly able to charge a cell phone. Never tried it but I don't see why it wouldn't have sufficient power - a cell phone is extremely frugal and has a great battery. The biggest obstacle would be getting the power at the right level to charge and circumventing proprietary plugs for phones.

      Are there practical crank chargers out there?

      Thus the sun charges the plant, I eat the plant, I crank the laptop. (Or you could insert meat into that supply chain if you wanted it less efficient but more tasty)

    • by Joce640k (829181) on Tuesday November 04, 2008 @04:08AM (#25623655) Homepage

      The CO2 produced by making those things is more than you'll ever get back from using them.

      Make one car journey less (eg. the one needed to go and buy the solar charger) and you'll probably achieve more green credit.

      • by stranger_to_himself (1132241) on Tuesday November 04, 2008 @04:49AM (#25623803) Journal

        The CO2 produced by making those things is more than you'll ever get back from using them.

        Make one car journey less (eg. the one needed to go and buy the solar charger) and you'll probably achieve more green credit.

        Probably right at the moment - but buying into this technology now will help drive development which hopefully will bring far greater long term benefits.

      • by pla (258480) on Tuesday November 04, 2008 @07:16AM (#25624421) Journal
        The CO2 produced by making those things is more than you'll ever get back from using them.

        That myth really needs to die, once and for all.

        You've phrased it one layer of indirection more than the standard claim (it takes more energy to make them than they will produce over the useful lifetime), but they reduce to the same concept (since virtually all of the CO2 "produced" during manufacture comes from the energy input).


        A trivial economic proof should demonstrate this fact - The payback period for wind or solar runs around 10 years on average (a lot less in ideal climates, somewhat more in suboptimal ones).

        The expected lifetime of such devices averages around 20-30 years (most importantly, more than the payback period).

        It follows, then, that in order for it to take more energy to produce the device than it will generate over its useful lifetime, the manufacturer would effectively need to spend twice as much on electricity as they sell the finished product for... And that ignores other overhead such as labor and raw materials.

        How many companies do you know of that sell at a massive loss and stay in business?
        • by Sebilrazen (870600) <blahsebilrazen@blah.com> on Tuesday November 04, 2008 @07:31AM (#25624477)
          GM, Ford, Chrysler?
        • by Tx (96709) on Tuesday November 04, 2008 @07:33AM (#25624491) Journal

          Rubbish. How many 10year old devices are you using? Even if the real lifespan of the device is actually accurate, the real world lifespan is much shorter. Technology moves on, different devices with different requirements come into vogue etc. For the type of portable devices in TFA, the chances of them being still in use in 10 years is minimal. Moreover, they are in many cases going to be occasional-use (the odd hike or trip) rather than daily use. It's not even worth doing any finger-in-the-air math to refute your claim, it's so obvious. You might possibly have a case for permanent photovoltaic panels on houses/buildings etc.

          • by bigmouth_strikes (224629) on Tuesday November 04, 2008 @07:55AM (#25624625) Journal

            Not rubbish at all. There are plenty of small photovoltaic panels that can power/recharge almost any powered gadget and there is little point in replacing those as often as the gadget. It all comes down to connectors. We have all this beautiful technology and we can't agree on their interfaces.

          • by pla (258480) on Tuesday November 04, 2008 @09:15AM (#25625227) Journal
            Rubbish. How many 10year old devices are you using?

            Gadget-scale, very few (an ancient Palm, an few graphing calculators, a watch, a GPSr... Not much more).

            On the appliance scale, however (which better matches the concept of alternative energy sources)... Fridge, washer, dryer, water heater, furnace, two TVs, my car (almost), stove, microwave, a handful of fans (from ceiling to box)... I could probably come up with a few more.

            The things we take for granted around the house, that we just expect to work when we press the button, tend to have real lifespans over ten years.


            For the type of portable devices in TFA, the chances of them being still in use in 10 years is minimal.

            What does the device itself have to do with anything? TFA talks about powering those devices, the devices themselves don't particularly matter. For an analogous situation, I have rechargeable AA batteries older than some of my current gadgets - Does that make rechargeable AAs not a viable source of portable power?
        • by Rogerborg (306625)

          Say: how many solar power companies do you know that power any of their production process, from extraction through to installation, using the output of their own products?

          We're in no hurry. Go do your Googling, and let us know what you find.

        • by dasunt (249686)

          That myth really needs to die, once and for all. You've phrased it one layer of indirection more than the standard claim (it takes more energy to make them than they will produce over the useful lifetime), but they reduce to the same concept (since virtually all of the CO2 "produced" during manufacture comes from the energy input). A trivial economic proof should demonstrate this fact - The payback period for wind or solar runs around 10 years on average (a lot less in ideal climates, somewhat more in sub

        • by akb (39826)

          I am big advocate of alternative energy but I don't think the application discussed is likely to be a net win for the environment. The payback period you refer to is for devices that are in more or less continuous use when the sun is shining. A portable device such as is being discussed will not operate anywhere near continuously, it will likely be folded up most of the time. Further, its extremely unlikely that a portable device would last 10 years or that the user would continue to find it useful for 1

      • 50% bullshit & 50% insightful, that's a pretty good ratio for /.

  • by Bwian_of_Nazareth (827437) on Tuesday November 04, 2008 @03:21AM (#25623455) Homepage

    I looked at the solargorilla but could not find any information about how much energy I need to generate with this device to reach the green break even - to offset the environmental cost of making this device. Anyone knows this information?

    • by TheLink (130905) on Tuesday November 04, 2008 @03:46AM (#25623563) Journal
      You can often have a good idea from the price tag if it's close enough to the cost of making it.

      While it's not exact, it shouldn't be that far off in those cases.

      If a device is priced at USD1000, costs USD500 to make, lasts 10 years and only saves you USD20 a year, it's probably not worth it in terms of the environment.

      While it's true that in some places they don't value their environment that much, it's still not zero - even in China they are starting to value it more, and so it will be added to the cost of making stuff there.
  • by Anonymous Coward on Tuesday November 04, 2008 @03:23AM (#25623461)

    These panels are ridiculously expensive, and produce a pitiful trickle of energy. Save your money and get a long extension cable -- or, if you absolutely need the portability, just get some extra batteries and lug them around with you.

    Solar is a great idea, but it's one whose time is not yet come.

  • Watch out (Score:5, Insightful)

    by Bruce Perens (3872) * <bruce@perens.com> on Tuesday November 04, 2008 @03:25AM (#25623467) Homepage Journal
    There are a lot of underpowered units with inferior solar cells out there, for sale at very large markups. You probably want a folding unit, with reasonably durable cells. The ones I've seen aren't so great. There was a 6-watt folding unit at Fry's for about $100. That's 6 watts in full sun in optimal conditions, not nearly enough to operate and charge your laptop at the same time.

    If you are running linux, the stuff in /proc/acpi/battery/*/* will probably give you the battery voltage in Volts and current draw in Amperes, and you multiply them together to get Watts. You need about twice that to operate and charge at the same time. Charging might be 60% efficient.

    • Re:Watch out (Score:4, Informative)

      by dgatwood (11270) on Tuesday November 04, 2008 @03:53AM (#25623593) Journal

      Not nearly twice the consumption to charge. My MacBook has a 60W supply. With a MacBook Pro, that's just enough to run it without charging; the battery won't charge, but it doesn't drain the battery, either. With the MBP's 85 Watt supply, it can do both. The EEE PC draws 24W or so at full tilt, 36W to charge. For an optimal charge rate, yeah, doubling the maximum draw is a good idea, but most laptop manufacturers base their power supply choices on 25-50% over the maximum drain, not double.

      On the flip side, this means that even with an ultra-low-power netbook, you're still talking about 4-6 of those panels before you start charging at all during normal use even in full sun. Solar panels on your roof: good idea. Solar panels on your laptop: waste of money, time, and materials.

      • Re: (Score:3, Interesting)

        by Bruce Perens (3872) *
        Are you sure? My Sony Vaio from 2004 with a Celeron M says it pulls 14 watts while compiling with parallel threads and with the backlight full bright, and gets down to 11 watts at minimum. The battery is only 62 Watt-hours when new, and it lasts a lot longer than an hour.

        If your laptop isn't charging with the smaller power supply, I suspect it is a bit too low voltage, not current.

  • by Joce640k (829181) on Tuesday November 04, 2008 @03:27AM (#25623475) Homepage

    I couldn't see a wattage anywhere and that makes me very wary.

    If you have to leave it a whole day to get ten minutes of power then it's not much use (and expensive!)

    • by TheLink (130905) on Tuesday November 04, 2008 @04:26AM (#25623721) Journal

      One link said 30W for 490 UKP. Another had a 60W product for 600UKP. So I shall use this.

      Assuming domestic electricity in the UK is about 16p/kwh ( http://www.britishgas.co.uk/pdf/Elec%20Price%20guarantee%202008.pdf [britishgas.co.uk] )

      600UKP = 3750kwh worth of electricity.

      Assuming very generously you get that 60w for 8 hours of sunlight (laugh if you're using it in the British Isles), this means 480wH a day = 0.480kwH a day.

      3750/0.48 = 7800 days = 21 years for that panel to make 600UKP of electricity.

      It does not appear to me to be a "Green" _alternative_ to mains power.

      BUT if you were intending to be temporarily in the middle of nowhere, that 600UKP for 60W weighing 2.6 pounds may start to look like a bargain. It will cost a lot more in time, resources, and environmental damage to pull power cables to your ever changing remote location.

      So is it a good option for _portable_ power?

      I don't know - it might still be worth considering other sources of power dynamo, generators, etc.

      2.6 pounds = 1.2kg. 1.2kg of vegetable oil contains 31MJ or 8.6kwH. It takes 143 hours of 60w to produce 8.6kwH - that's 18 days of 8 hour sunlight.

      Yes there are inefficiencies in converting cooking oil to electricity, or diesel to electricty.

      So do more thorough estimations/calculations to see which makes more sense for your scenarios.

      If you're only spending a short time from mains power, it probably makes more sense to carry enough rechargeable batteries to last the whole time.

    • Re: (Score:3, Informative)

      by dajak (662256)

      I was also looking for that. The solargorilla spec does list .5 Ah @ 5V (usb) or 20V (power socket). If I understand things correctly, this means that it delivers 10W in ideal conditions if you use the power socket. Not impressive. I'll pass.

  • by Ptur (866963) on Tuesday November 04, 2008 @03:28AM (#25623483)
    I'm still waiting for the first netbook or laptop to feature solar cells in the lid, instead of the stupid logo they put there now.

    Come on, it can't be that hard? And don't tell me I'm the first to think of this?
    • Re: (Score:3, Insightful)

      by Sod75 (558841)

      So you want to leave your laptop out in the searing sun for hours straight, just to charge the battery for a tiny amount (not a lot of solar panel space) ?

      • Re: (Score:2, Interesting)

        by rusl (1255318)
        Why does the panel/crank power supply have to be in the same spot as the laptop? Obviously it would be optimal to only have one battery and that should be with the PC. But a wire can transmit a charge - I do believe. Not exactly universal roaming but putting the panel in the window 30ft away wouldn't be totally impractical.
    • Re: (Score:3, Insightful)

      by Firehed (942385)

      You're not the first to think of it by any means, though you may be the first to think it's practical. Given the surface area of a netbook (not much), I don't think that even a 100% efficient panel covering the entire lid would provide enough power, let alone the 20-25% that most panels provide these days. Combined with the fact that netbooks are (usually) designed to be cheap... it's a ways off.

      How often is your laptop lid exposed to sunlight anyways? I think my MBP has for twenty minutes or so over the

    • The amount of charge you'll get will be tiny, far too small to be really useful*. Any ideas of leaving it on a windowsill for an hour to charge it are laughable.

      [*] Unless you happen live in the desert, a long way from any electricity and only need to use it for 20 minutes per day.

    • Re: (Score:3, Interesting)

      by apodyopsis (1048476)
      theres a reason why the OLPC had a hand crank.

      I thought of the same idea ages ago but there was a couple of differences...

      1. no backlight, make a system with a clear mono LCD with a mirror/diffuser that allows you to light up the screen naturally on a bright day or shine any other light sauce into the back on a darker day.
      2. no HDD, no moving parts - we are beginning to see this with the EEE style netbooks
      3. very low power chip - forget the feature creep that is already entering the netbook market.
      • by wazzzup (172351)

        or shine any other light sauce into the back on a darker day.

        Do NOT follow this advice. I totally ruined my laptop thanks to this clown. Before you reply saying I did it wrong using a Burgandy or some other heavy gravy I did not. A Hollandaise was all that I applied and I even used margarine in place of butter.

    • You aren't the first to think of it. Someone too lazy to do the maths posts this suggestion every time there is a story about solar power. The bottom line is that you'd get a maximum of about ten minutes extra run time, assuming theoretically perfect solar cells (i.e ones that don't exist yet) and you aimed the lid towards the sun. In real use, with current technology, you would get around 30 seconds of extra battery life and double the cost of the laptop.
    • by farnsaw (252018)
      New Laptop: $599 New Laptop with Solar Lid: $850 Now how many of those do you think they will sell?
    • Not feasable by any means.

      For example, this Asus Eee uses around 15-23 watts when in use, and around 4 watts in standby. The area on the lid is enough to produce up to 6 watts of power from high efficiency solar cells in ideal sun conditions, but those conditiions would mean you couldn't see the screen because you'd need to angle it towards the sun and it would get extremely hot - have you ever touched a solar panel when it's sat in the summer sun for a length of time? you can almost burn yourself.

      I'm s
  • Other locations. (Score:3, Informative)

    by Gnea (2566) on Tuesday November 04, 2008 @03:34AM (#25623507)

    Frys.com [frys.com] has some affordable solutions. Pricewatch [pricewatch.com] seems to have a scant selection, although very unique.

  • "Green Revolution" (Score:5, Interesting)

    by lobiusmoop (305328) on Tuesday November 04, 2008 @03:35AM (#25623519) Homepage

    While the sentiment is admirable, please don't use 'going green' as an excuse to buy more toys; just buy the toys. Realistically, the power ranges you are talking about are in the 50-100W range for portable solar charging. In comparison, a typical 100 horsepower car is using around 75KW. (1HP=750W), so the power savings possible by simply traveling less dwarf anything possible via solar.

    If you are _really_ concerned about going green, the biggest (and likely simplest) impact you can have is to never have children, especially in the developed world where per-capita energy consumption is highest.

    • Re: (Score:3, Funny)

      by jamesh (87723)

      If you are _really_ concerned about going green, the biggest (and likely simplest) impact you can have is to never have children

      That's rubbish and you know it. A child in a suitably sized hamster wheel can produce enough energy to run all manner of electrical equipment. And once they are grown enough they can pull a cart, removing the need to own or drive a car.

      Once matrix-style energy extraction is perfected, the future of the world will depend on having more children!

    • by Tjeerd (976354)
      I do think that the 21st century will have some sort of "green revolution", it's just a name which everyone quickly understands. It's not a perfect term. I myself don't own - and never had - a car and do everything by bike or by using public transport, so that already helps a little bit in saving energy I think. Furthermore I was also thinking about production/transport/etc. of the solar panels which might also cost quite some energy. So in the end a solar energy panel wouldn't differ that much from electr
      • by Whiteox (919863)

        Keep in mind that there are some solar panels that can be recycled. I'm collecting the small panels from solar garden lights that people throw away (mainly because the rechargeable batteries have died). They also contain a small circuit board, a light sensor and an LED. The circuit board has inputs and outputs for charging, (typically 3v) and illuminating.
        What's interesting for me though is that I'm going to get a few, connect them into series that will charge a battery, the output of which will be hooked t

    • by adavies42 (746183)
      And people mock me when I say greens hate people....
    • Re: (Score:3, Insightful)

      by value_added (719364)

      If you are _really_ concerned about going green, the biggest (and likely simplest) impact you can have is to never have children, especially in the developed world where per-capita energy consumption is highest.

      A well reasoned and thoughtful post, but the above bit borders on the absurd.

      That child, given all the benefits that the "developed world" offers is more likely to grow up and discover the solution to our energy problems than someone living in a tribe somewhere in a rainforest living on roots and ban

      • No, having no children will solve the problem. You, and many others, have the very common inability to comprehend low probability events. Let's presume that, over the next four generations, you get 2000 geniuses who could reasonably advance science to the point that we could cut our impact on the planet by 75% in terms of energy used or energy directly from solar. That's revolutionary, given the immense resources we use in the world, and would require a massive shift in the way things are done in addition

    • by TheLink (130905)
      I doubt these toys are green.

      600 UK pounds is a lot of money.

      There's a reason why they are expensive - it's because they require big factories, lots of power and clean water to make.

      Even if you have economies of scale, it'll take a while before they are as cheap as equivalent sized LCDs or plasma TVs - which aren't a dime a dozen either.

      Personally, I'd rather have a reasonably portable and efficient fuel cell that can convert cooking oil (or other edible stuff) to electricity.

      Then at least the human and gad
    • If you are _really_ concerned about going green, the biggest (and likely simplest) impact you can have is to never have children, especially in the developed world where per-capita energy consumption is highest.

      The generally accepted age of the earth is about 4.5 billion years. Say what you will, but this would indicate the earth is pretty good at maintaining itself. Pump out all the greenhouse gases and pollution you like, the earth isn't going away.

      But "going green" (yes, overused phrase) isn't founded on concerns that the earth will cease to exist. It's based on concerns about the earth maintaining itself so that it can sustain human life.

      This is why I don't understand why you would then suggest gradually end

  • by lkcl (517947) <lkcl@lkcl.net> on Tuesday November 04, 2008 @03:40AM (#25623541) Homepage

    Before saying "I have found a way to save the planet!" check that the cost in planetary terms of the product is worth it:

    http://www.genersys-solar.com/carbon-savings/carbon_footprint_solar-panel_manufacture.asp [genersys-solar.com]

    seems to be saying that there's a reduction of the carbon cost when compared to other power-generation mechanisms, over the expected 35 year lifespan of the home-sized solar panels.

    are the small, portable solar panels you're advocating as carbon-friendly?

    • by Whiteox (919863)

      Nice Work! Even in the short term, if a mobile phone was designed with a smattering of solar cells, it would certainly extend its use/day.

  • by EEthan (1353209) on Tuesday November 04, 2008 @03:56AM (#25623599)
    In my experiences dealing with photovoltaic power supply systems of all sizes, I've become convinced that solar panels are currently not a viable solution for powering mobile devices for a few reasons, mainly cost, unreliability, and inefficiency.

    First of all, look at how much these things cost. the Portable Power Pack retails online for 420 pounds, or about $660. You could buy more than a dozen eeepc batteries for that much and just keep them stocked in your car or rucksack or whatever. LiIon batteries aren't terrible for the environment, and you won't even need sun to use them...

    Speaking of the sun, I live in beautiful southern California, where one can definitely count on the sun 99% of the time. But most parts of the world aren't that sunny, and even if the sun is shining there's bound to be a tree/building/civilization in the way just when you need it most. You're not going to walk or drive around the city looking for a nice open space to sit in for an hour and roast while you check your email, just so you could feel good about spending $600 on a solar panel, no matter how good your intentions are.

    so how do you charge your devices with a solar panel while actually "on the go"? you can try to drape it over that rucksack of yours while you're walking somewhere, but if the panel isn't facing the sun directly you won't get anywhere near the peak power output advertised. Instead, you need to find an open space and lay out your few-square-foot mat-- and then you're tied to the ground.

    And what about that generous peak power they keep advertising? solar panels output their peak power when they are laid out flat, directly facing the sun, on a completely clear, sunny day. I know from personal experience with small panels that small deviations from the sun-facing angle mean big drops in power.

    So alright, let's say that you bought a 30 watt panel and it's noon on a clear, sunny day, so you're getting 30 watts out of it. Please correct me if I am wrong, but I believe that EeePCs use 36 watt power adapters. How do you plan on charging and using your EeePC on less than 36 watts WHILE charging your phone and whatever else you have plugged in? all you could possibly do is increase your battery life considerably-- which might be great, but i'm not sure it justifies the costs and the effort involved.

    Here's my suggestion: Save the money you were going to spend on that portable panel. Use a little to buy extra batteries for your gadgets, and put the rest in a savings account. Save up for a large, multi-kilowatt solar system for your house, which will save a lot more greenhouse gas emissions per dollar you spend than one of these portable things. Use that home solar system to charge your batteries, and you're gold... er, green.
    • Re: (Score:2, Informative)

      by Anonymous Coward

      I have a 75W solar panel for the camping and did some measurements for my U9200 Fujitsu-Siemens laptop (Core2Duo CPU T5450, 2GB RAM). I connected the laptop to solar panel's charge controler via Trust's universal car adapter (http://www.trust.com/14669).

      While using default setting for CPU voltage (1.25V), laptop was drawing 3.8-3.9A (46-47W) at full load with the CPU temperature over 70 degrees Celsius and fan on the full speed. Since max. current for this panel is around 5A in ideal conditions, this means

  • by Dice (109560) on Tuesday November 04, 2008 @03:58AM (#25623605)

    The power brick for my laptop claims that it draws 65 Watts. The average incident solar power per square meter on Earth is 1000 Watts. If we assume a solar cell with 30% efficiency I would need 65/300 = 0.216 square meters of solar cell for my laptop. That's a square 46.5cm on a side, or around 18.3 inches on a side.

    Not too bad, but not something I would carry with me unless I was severely limited in terms of power sources.

    • by tkw954 (709413)

      That's a square 46.5cm on a side, or around 18.3 inches on a side. Not too bad, but not something I would carry with me unless I was severely limited in terms of power sources.

      Add a fold in each direction and now you're down to the size of your laptop.

    • by asc99c (938635)

      That's interesting maths, because it means that if you could ever get to 100% efficiency, a solar panel convering the lid of the laptop would be just about right to power the device.

      But even with current technology, if my laptop at home had a solar panel built into the top, that could provide most of the power I need for it, as long as I leave it on the windowsill while I'm at work.

    • Solar cells are a lot less than 30% efficient, nearer 10%. Not all the incident power is in the band that can operate a solar cell. The actual solar flux is nearer 680W/m^2, and you then have to allow for clouds and the drop off in collection power as the surface ceases to be normal to the incident solar radiation (there is additional input from scattered light from the sky, but this drops off with lower solar angle, i.e. early morning and evening).

      You are going to need around a square meter for your laptop

    • by capnkr (1153623)

      Remember to find yourself (after you find that 30% efficient cell, which I don't think anyone is really commercially producing yet) a cloud-free, sunny day, and to keep the face of that panel at 90* to the suns rays at all times, or the power drop will be so precipitous that your laptop won't even charge.

      I've lived with solar for 4 years now; it provides the 12V for my boat systems - charging, lights, radio, etc... Experience solar in the real-world for a while, and you will find that basically you need a l

  • by dirkjan (28041) on Tuesday November 04, 2008 @04:04AM (#25623633) Homepage

    I had a Solio Classic to charge GPS logger and phone while hiking for multiple days. It worked okay, good in very sunny conditions (in northern europe) and not enough to keep up on clouded days. But it was stolen and now I have a Solar Mio 31 which works better, even in clouded conditions. It manages to keep the batteries of a mobile phone and GPS logger charged in average dutch weather, back pack mounted or behind a south facing window. As I also use it at home, I haven't touched the normal chargers in a year...

    As for price or "greeness", they won't repay themselves financially or impactwise. But I see part of it as gaining experience with solar cells and it is nice to see your week long treks through nowhere in google earth...

    • by steevc (54110)

      I bought a Freeloader solar charger to play with. Unless you can leave it outside in full sun, and keep moving it to maintain optimal angle I find it can barely keep my phone going. Generally it gets much less solar exposure. Windows, clouds etc drastically reduce the charging. In a British winter you have no chance.

      I didn't expect it to pay for itself. I see the benefit of PV to be when you don't have access to other power sources. You see panels on some roadside devices that might have cost more to connec

  • To generate enough power to run a laptop, even a netbook, you will need solar cells with a peak output of hundreds of watts, unless you live in Arizona or a similar place. Cloud cover reduces output dramatically. Cells only produce maximum power when the line from the sun is normal to the surface, and for fixed cells this can only be true for a short time every day. To get maximum utilisation, cells really need to be on a tracking system that rotates in two axes throughout the day, but this is likely to be
  • by SJrX (703334) on Tuesday November 04, 2008 @04:10AM (#25623663)
    I had done quiet a few bike trips and generally can't be without my iPod, PSP, and cellphone so I have had some experiance using Solar Panels previously, though never for something as power hungry as a notebook/netbook. Two years ago I purchased the Soldius 1 Solar Charger, seen here: http://www.thinkgeek.com/gadgets/travelpower/7d34/ [thinkgeek.com]. I found that even stationary it really just drained my iPods batteries and made them unusable, as the change in voltages associated with clouds would cause the iPod to constantly redetect that the charging had started and illuminate the screen thus draining more power. I may have only gotten one meaningful charge or two out of it, in the two years I've had it. It also didn't charge some devices, that were USB powered, and seemed very brittle. This summer past, I had taken time off to go cycling for 2 months across Canada, and so invested in another Solar Panel, the SolarFocus SolarMio 31 Solar Charger: http://www.mec.ca/Products/product_detail.jsp?FOLDER%3C%3Efolder_id=2534374302697169&PRODUCT%3C%3Eprd_id=845524442620595 [www.mec.ca]. It was very durable, and I had it strapped on my rear rack, even in the worst rains. It also has a portable battery pack so you can charge during the day, and then have power for later, and it charges relatively quickly. I found that 4 hours would give it a full charge to the battery, (it is probably much better than this, as being on my bike rack and in motion means that it is not really positioned for optimum solar energy collection) and that would charge my iPod to 90%. It also has an external AC adapter to charge the battery overnight, and a USB port for 'most' USB devices. Some draw backs are that it didn't charge my Phone at the time, a Motorola KRZR, and after my trip I found out it doesn't charge my iPhone (which is kinda a disappointment). Another plus is that the battery is detachable, and while replacements/spares are expensive, it made it convient to charge at camping sights. They make an equivilant solar panel for laptops which is a bit pricer at CAD $595: http://www.mec.ca/Products/product_detail.jsp?FOLDER%3C%3Efolder_id=2534374302697169&PRODUCT%3C%3Eprd_id=845524442625524 [www.mec.ca]. Which is too rich for my blood at the moment, but if the quality is anything like this one, I'd definately recommend it. Finally some other words of wisdom: 1) The Solar Device compatibility list actually seems to matter at least for obvious devices not listed, just because it's USB doesn't mean it will charge it. 2) Getting a dead iPod (I had both a iPod 4G Photo and 5.5G Video) to charge is a bit tricky if you are charging straight from the sun in less than ideal conditions, as when it turns on, the screen comes on maximum brightness, and I believe stops charging for a moment, and will cause the iPod to turn off. I found that both the above would eventually charge by just booting it into Disk Mode a few times, eventually it would have enough power to stay on in Disk Mode and charge. Finally after two minutes rebooting it into Normal mode, so that the screen turns off resulted in a quicker charge.
    • by evilad (87480)

      I had good luck cycling with a 4-cell solar AA charger and an iPhone "emergency power" battery pack which coincidentally took AA batteries.

    • Re: (Score:2, Interesting)

      by leodavinci0 (1197081)
      I found a cheaper solution to charging my iPhone by solar. I use two solar arrays, very similar to those found here for $23 each: http://www.batteryjunction.com/12vsopabachs.html [batteryjunction.com] They deliver 150 mA max, but I've found they can easily deliver 175 mA each, and not even when angled directly at the sun. I use this with a simple car power inverter that has a USB charger port on it, but you can always make your own 12V to 5V regulator with a 5V regulator from Radio Shack, see here: http://www.radioshack.com [radioshack.com]
  • by shomon2 (71232) on Tuesday November 04, 2008 @04:40AM (#25623773) Journal

    I wouldn't go for the fancy laptop bags with solar panels... Maybe they work well, but if you're a real geek why not build your own? To run a regular 15-24v input laptop for 6 hours a day you'd need:

    2 x 30W Mnocrystalline Solar Panels
    1 x 6amp Charge Controller
    1 x 85 Ah Deep Cycle leisure Battery
    1 x Cigar to Crocodile Clip Adaptor
    1 x Universal Laptop adaptor

    At least that's here in drizzly old england. Comes to around 250 pounds in our drizzly english money.

    Carbon costs and payback aren't everything: computers today aren't green and aren't sustainable but don't just get sad and do nothing :)

    Using solar panels for this means microgeneration and helps promote use of decentralised, off grid energy which I consider a positive social change towards green-ness, and it will help you in particular if you live in a place with frequent blackouts (i.e not the UK!). Think of it as a ticket to a cheap shed-studio setup, or temporary remote setups like at festivals or camping, and once it's all wired up and charging a battery, I can plug it into loads of other kinds of things.

    Ale

    • Re: (Score:3, Interesting)

      by Alioth (221270)

      It also weighs about 250 pounds in our drizzly, imperial weights.

      As an experiment, I got an 80W monocrystalline panel to power stuff in the garden. It was going to cost me just as much to lay and connect up mains cables, so I thought it would be a good time to experiment.

      The conclusion is that current technology solar panels aren't all that useful or cost effective. Even on a nice day, you can only count on averaging something like 10% of the panel's rated output (due to the hours of darkness), so over a pe

  • That is definitely the determining factor.
    Even if you think that the area you live is a sunny area (worthy of solar power) do some independent fact checking on the amount of sunlight which actually reaches the ground where you live, not just the amount of "sunshine" during the day. It might be less than you think, and humans are notoriously bad at subjective probabilities.

  • PowerFilm (Score:4, Interesting)

    by DynaSoar (714234) on Tuesday November 04, 2008 @05:20AM (#25623923) Journal

    The foldable you mention is from PowerFilm. They make many different devices as well as components for building your own. http://www.powerfilmsolar.com/products/portable%20and%20remote/index.html [powerfilmsolar.com]
    I went the build-your-own route using their thin-film cells. I needed a power source for a laptop in the field, so I put one together that I could epoxy to the laptop lid. It's still on duty 4 years later. I also needed a source on board the ultimate portable device -- a rocket weighing less than 2kg total and capable of handling a vertical acceleration of 20 G to Mach 1+, supplying constant high grade power to the recording altimeter that also controlled the parachute ejection system. That system has flown over 20 times. I put their stuff through some hellacious stress testing and the only failures I've had were my fault.

  • Decomas (Score:3, Informative)

    by Decomas (1342753) on Tuesday November 04, 2008 @06:17AM (#25624165)
    Yes! I actually have that EXACT model from the first link. It is 20 Watts and I run all my usb devices off of it simultaneously. I think I got up to about 7 or 8 devices at once before it reached its peek. It's great, I worked at the beach all summer and carried the panel in my bag every day, only taking up the size of a thin composition notebook. and the great thing is, IT FLEXES like a softback book. So there is no need to worry about breaking the "glass" on the panels.

    NOMADIC POWER!

    I want to get the Y adapter and bump my power up to 60 watts with a 2nd solar panel. I would suggest E.Bay for some great deals on these panels. such as this. http://cgi.ebay.com/35-Watt-Foldable-Solar-Panel_W0QQitemZ190262865303QQcmdZViewItem?hash=item190262865303&_trkparms=72%3A1205 [ebay.com]|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3911.c0.m14
  • anybody installing solar plants on their roof, that will "break even" in more than 10 years (be it carbon or price) is heading for a huge delusion. There are many different things that can go wrong in the next 10years.
    • cost of maintaining the plant. Most materials , when left outside under sun and rain, do degrade; steel will rust, plastic will rot; you will need to repair, rewire, buy anew, etc etc
    • atmospheric events. Too much snow, a violent thunderstorm, etc etc, can destroy your valuable plant much ea
  • one hundred forty pounds ?

    Let's do a little math.

    Let's assume these are the very best of next decade's solar cells, say 30% efficient. Let's guess they're about 10x15 cm. Also assume we are not in England so the sun shines maybe 30% of the time. crank, crank, crank.... this gadget can at best supply very nearly ONE FREEPIN WATT !!

    This notebook I'm typing on draws about 30 watts, so this expensive gadget would let me run the laptop for about 50 minutes per day in Tuscon, Arizona.

    Or looked at another way,

  • 10 Watt Solar Panel : $250.00
    Price of electricity: $0.0775 / Kilowatt Hour

    You have to leave the Solar panel in the bright sunlight for 100 hours, which is over a week at 12 hours a day, just to product ONE kilowatt Hour of electricity that you could have purchased for approximately 8 Cents.

    Now lets extrapolate on that.
    1 Week = $0.08
    1 Year = $4.16
    10 Years = $41.60
    50 Years = $253.00
    So, you would have to purchase one of these, hook it up to a power storage system, and run it in perfect conditions fo
  • I found that the recharge time (Solio Hybrid, but presumably same for other small solar chargers) is so long as to be typically impractical. How often are you really willing to leave a ~$100 device lying around _outdoors_ for hours on end? Inside your car windshield isn't good enough: the device overheats and stops operating at in-car in-sun temperatures, and glass filters out wavelengths apparently preferred by the solar panel.

    Advantage of the Solio Hybrid is secondary charging from USB: fill it up at your

  • ... for a week-long backpacking trip in the Wind River mountain range [willden.org].

    My requirements weren't large, all I wanted to do is to be able to recharge my Palm Centro. I knew I wouldn't have phone service, but I wanted to be able to use it as an e-book reader and music/audio-book player. I love the 140W panel I mounted on top of my camp trailer, so a small, portable solar panel that I could carry with me seemed like exactly what I wanted.

    What I found is that there are a lot of inexpensive, lightweight, poor

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