Solar panels to power laptop

Discussion in 'Buying Tips and Advice' started by a.k.a. Melvin, Sep 29, 2005.

  1. a.k.a. Melvin macrumors newbie

    Joined:
    May 16, 2005
    Location:
    Studio City, CA
    #1
    I am going to need a solar panel to power my 12" PowerBook. Do any of you have experience with this sort of thing and can anyone recommend a durable, reliable brand of solar panel? Maybe even a solar panel that could also charge up other devices such as a cell phone, PDA, etc...

    Thanks!

    Mel
     
  2. RedTomato macrumors 68040

    RedTomato

    Joined:
    Mar 4, 2005
    Location:
    .. London ..
    #2
    I'm quite interested in this too.

    I regularly saw people powering laptops and mobile phones off solar panels and bicycle-powered generators at various green festivals around the UK.

    This was several years ago, and I briefly explored the possiblities of hooking a panel up to my IBM Thinkpad, but I was scared off by the electronics required.

    Shame, as I would have quite liked to just velcro a panel onto the back of my Thinkpad screen, and enjoy maybe an hour's extra battery life from the tricklecharge topup effect.

    I'd be interested to see how the technology has progressed re ease of use and pricing.

    Modern solar panels are more efficient but modern laptops are so much more power hungry, I expect the net effect on battery life to be much the same as it was several years ago :rolleyes:

    Whether I can bring myself to glue a solar panel to the back of my darling PB is a different question entirely :D

    xoxo RedTomato
     
  3. carpe diem macrumors 6502

    Joined:
    Sep 18, 2005
    #3
    Some company makes on for ipod but i dont know about pc's.
     
  4. TheMonarch macrumors 65816

    TheMonarch

    Joined:
    May 6, 2005
    Location:
    Bay Area
    #4
    Those are called 'Trickle chargers' and they won't give you enough juice to power a laptop. They give you minuets of power for hours of charging in the sun...
     
  5. Makosuke macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #5
    You might have a look at Gaiam.com, if you haven't already. I haven't actually used the PV chargers they have, but other things I've bought from them have been solid products, so I get the feeling they carry decent stuff.

    A 20W charger is quite pricy at around $300, though, so be prepared to pay (and you'll definitely do better with a 12" screen, on account of the lower power draw).
     
  6. RedTomato macrumors 68040

    RedTomato

    Joined:
    Mar 4, 2005
    Location:
    .. London ..
    #6
    Juat had a look at the stuff on gaiam.com

    Woo! Pricey! But then it's a 'lifestyle' company...

    Couple of things come to mind:

    Solar panels put out DC, and laptops work on DC, so it seems there is no need to buy an inverter - I think that's for converting DC to AC so that you can run things like TVs or fridges (if you haven't brought special 12v DC fridges / TVs)

    Apple laptops come with some highly intelligent power management electronics based in 3 locations int he power supply chain:

    i) the Apple transformer on the charger cable - deals with any wall-supply voltage globally, also cleans and rectifies it, (which can legally vary -+ 10% from the offical figure) and outputs reasonably clean DC

    ii) the electronics inside the battery - regulates cell charging and discharge rates, also deals with the highly variable power requests from the laptop and the variable supply from the charger cable.

    iii) the laptop internal power control unit - switches between battery and mains, and works out how much to take from the mains and how much to give to the battery - it can deal with some Apple chargers being 45watts, and others being 65 watts.

    With all this thingmajiggery, I, who know almost nothing about electronics, feel it should be entirely feasible to slap together some solar panels, either in paraller or in series, to get roughtly the right voltage, and feed that into somewhere in the Apple power supply/management chain, with Apple electronics taking care of cleaning and limiting and using it.

    Could someone wiser in the ways of electronics tell me if i'm talking bollocks?

    Thanks,

    RedTomato
     
  7. joecool85 macrumors 65816

    joecool85

    Joined:
    Mar 9, 2005
    Location:
    Maine
    #7
    I'm pretty sure that our 'books charge on 24volt DC. What I would do to make sure it is clean, is get two 12volt dc batteries, a 20w (or larger) solar panel, and two 12v regulators. Hook up the 12 volt regulators and then hook the regulators in series to get 24 volts. (12v batteries give off 11.5-13.9 volts dependant on charge). To charge the batteries hook them up in parallel with the panel. You might want to get a charge controller unless you are good with electronics (and you said you weren't, so I would seriously think about it.) Your other option would be to grab two 20w panels, two 12v regulators and hook up one regulator to each panel, then hook that in series to give you 24v. As long as you had even ok sun you should get 24 volts. 12volt panels normally go up to 16volts in full sun and down to 11/12 in dim light. Hope this helps. Good luck.
     
  8. RedTomato macrumors 68040

    RedTomato

    Joined:
    Mar 4, 2005
    Location:
    .. London ..
    #8
    Mmm thanks that's useful info.

    Quickly looking for prices seems to indicate that 20w 12v solar panels are about 60cm x 20cm EACH - about twice the area of a closed 15'' PB.

    Also they're about the same weight each - 2kg.

    Prices are nearly £200 for a 12v 20 watt and £100 for a 12v 10 watt.

    2x 20watt is about 40w - nearly the same as an Apple 45w charger , also the ouptput amperage is roughtly the same.

    Would be almost half a meter square and weigh 4KG and cost about £400 ($600) (assuming you're not using external storage batteries)

    Backpackable, but not something I'd want to carry on a regualr basis.

    The fact that it's backpackable at all is something of an acheivement tho :)

    Has anyone here actually used / built a solar power supply for a laptop? (Hooked up directly I mean.)

    cheers

    RedTomato
     
  9. a.k.a. Melvin thread starter macrumors newbie

    Joined:
    May 16, 2005
    Location:
    Studio City, CA
    #9
    I'm not really looking for a solar panel to provide constant power to the powerbook. What will suffice would be a solar panel that could adequately charge the batteries when I have down time. I only anticipate needing the computer for a few hours a day and a few hours in the evening.

    Thanks all!

    Mel
     
  10. amy80a macrumors newbie

    Joined:
    Jul 3, 2011
    #10
    I'll echo A.K.A Melvin's post. I would only be needing a solar panel to charge up the batteries of my Mac since I don't really use it for a long time except when I go on trips where a power outlet isn't readily available.
     

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