Solar Powering a laptop

Discussion in 'MacBook Pro' started by szsiddiq, Nov 25, 2006.

  1. szsiddiq macrumors 6502


    Dec 21, 2005
    I've been doing some research into this, and wanted to know if anyone here had come across anything similar or mac specific. i wanted to kno if there was a way to create a solar power recharger for a laptop.
    any ideas? from what i kno, the difficulty would be converting the power from an irregular source to a constant source.
    feel free to use engineering language.

    wow, there's an ad for solio at the bottomof the page. didn't know these ads were targeted! Anyways, i was looking for something that could be built in.
  2. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    It's common for people on sail boats to depend on wind and solar power. I've learned a little through that route. First off the solar system you propose needs to be rather large. What you need to determine is the ratio of charge time to use time. Do you want to charge the system for three days so that you can use it for three hours. Or would you prefer to fully charge a dead battery in three hours. Or do you want to be able to use the notebook and recharge it at the same time.

    In the sailboat case, people make an energy budget based on (say) 1 hour of usage every day for a computer (for weather faxes, email,..) and then the lights, water maker and so on. So your first step will be to determine how many Watts of power you need.

    Next a few real world engineering guidelines.....

    The best way to do this is to use a deep cycle lead acid storage battery connected to the solar array. This gets charged whenever the sun is out. For a small array you can simply us a diode as a "controller" so the battery does not discharge through the array at night. Then you connect an AC inverter to the lead acid battery. and you connect your Apple AC adaptor to the inverter.

    You need to de-rate the sollar panne's published power in watts y a factor of two. Reason being is that rateedpower happens only at noon what the path of sunlight through the atmosphere is minimum. At other times you have longer path. Also account for the fact that your pannels are not mterized and do not track the sun. Factor of two works well. This assume no shade and you pannels are tilted to angle equal to your longitude. and facing due south De-rate father if you can't angle the panels correctly.

    Next assume an 8 our day on yearly average or for any given day only 3/4 of sunrie to sunset hours are usable.

    Size the storage battery "way large". The lifetime of the battery depends on the level of discharge. Going past 50% will kill even a deep discharge battery quickly. Buy at lesat 4x as many amp hours as you need

    It should be clear that a 100W charger s not a portable device. It will take about 300 pounds of equipment to do it right.

    The other way to go is to skip the storage battery and AC inverter. I don't think this is as practical. You would only be able to charge the notebook when the sun is overhead and you would still not have a portable system. The way to do it would be to buy a panel that puts out abut 16V and then use a DC regulator to supply the correct charging voltage to the computers. But you don't save much a 100W panel is never going to be portable

    Adding a storage battery means you can use a much smaller solar array. Batteries are cheeper than panels. With the battery all the sunlight is put to use without a battery the sunlight is only put to use when the notebook is plugged in. With a battery you can charge the notebook at night

    One more idea: For a small system, you could buy a small UPS. Connect the solar array to the UPS' internal battery (diode in series) then you plug in the Apple AC adaptor to the UPS. Yo are ineffect using the UPS as a battery and inverter saving some work
  3. szsiddiq thread starter macrumors 6502


    Dec 21, 2005
    thanks for your response! i'll keep looking into it, but based on my initial research, its probably not worth it.
  4. pianoman macrumors 68000


    May 31, 2006
    there's a backpack on the market that has solar panels on the back so it can charge whatever's inside it. check this out.
  5. szsiddiq thread starter macrumors 6502


    Dec 21, 2005
    yea, ive seen stuff like that. ive seen a DIY iPod solar charger too. How useful/stable would that be though? id hafta test it out
  6. szsiddiq thread starter macrumors 6502


    Dec 21, 2005
    hmmm, i guess i shuda made it clear that i want to build this into the laptop
  7. AmbitiousLemon Moderator emeritus


    Nov 28, 2001
    down in Fraggle Rock
    I understood that, I just thought it would be easiest to take one of the systems already created and modify it to be part of the laptop. I thought it would be easier since it is already small (since I linked portable systems) and it already has all the necessary hardware to charge a laptop. The flexible one might be really easy to cut apart.
  8. grum macrumors regular

    Jul 22, 2006
    dunno how relevant this is but i read a book about mountaineering and it described how on expeditions Chris Bonnington would use his Apple Mac to play chess. I wondered how he would power it and assumed it was via some kind of solar power device.
  9. j26 macrumors 65832


    Mar 30, 2005
    Do you really want to leave a laptop lying in the sun all day? It's a guaranteed recipe to destroy it (or at least bleach the crap out of it)

    Some sort of foldable panel that you can hide the laptop under to shield it from the sun would be a better idea.
  10. balamw Moderator


    Staff Member

    Aug 16, 2005
    New England
    I've been thinking along these lines for a while too, I'd really like to be able to capture some of the sun's bounty and make my computing experience a bit more eco-friendly.

    What I've been imagining is a system into which the battery can go and be charged outside the laptop, so even if it may take a long time to charge a battery. Every so often the solar battery can be placed into the laptop.

    Seems more practical to leave a $100 battery in the sun than a $1500 laptop...

  11. szsiddiq thread starter macrumors 6502


    Dec 21, 2005
    thanks for everyones input! if i added solar panels, it would just be to capture a minimal amount of energy during the day, so as to increase battery life from 4-5hour to 6-7hours. if its relatively cheap to do (under $30) then a mod to allow for even an extra 30mins would be worth it for me.
    im gonna keep looking into it.

    i might also look into using a thermocouple and a voltage regulator to capture heat. this might be pretty expensive tho.
  12. excalibur313 macrumors 6502a


    Jun 7, 2003
    Cambridge, MA
    I too think that it would be a great idea to have something like this. I just have these visions of the aluminum top of the macbook pro being replaced by a solar panel in the same dimensions. It seems pretty amazing and if I was a little more tech savvy I would probably do it myself. I wonder if anyone has...
  13. flir67 macrumors 6502

    Jun 23, 2005
    check out they have 16volt solar rolls for 350.00. and they have notebook size folders too.

    I was thinking of buying one of these recently. all you need is a 12v auto voltage converter. I have a 140w inverter purchased from wallyworld for 20.00. worked great on my old ibook.

    all you need is sun and cellular connection and your global. :)

    best of luck

  14. zacm macrumors newbie

    Jan 18, 2007
    Solar Powering A Laptop

    I can totally recommend the Sunlinq 12W solar charger which I got from over the summer. It comes with a female car cigarette adaptor so as long as you have a regular car cigarette lighter adaptor for your iMac, you're in business!!!!

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