Solar Powered PC

First post....
I am planning on putting together a solar powered mini itx form factor computer. I am planning on putting it in the shed in the back yard. According to Via, the motherboard should consume 20w under full load. This machine is going to be ran headless so powering a monitor will not be an issue. I figure after I install a 1GB stick of ram an optical drive and a laptop drive the entire setup shouldnt consume more than 50-60w total. I am looking at getting a deep cycle battery to power the pc. The pc will be using a DC to DC power supply(typical car pc PSU)
So my questions are as follows:

How many AH should the battery be able to supply?
How many watts of solar will i need?
Are there any components I am overlooking?

Comments

  • Solar GuppySolar Guppy Posts: 1,959Solar Expert ✭✭✭
    Re: Solar Powered PC

    You'll need a 12 volt suppy for the motherboard ... www.mini-itx.com has some high efficiency ones that plug into the mothermoard header

    I've built a few of these, my 600mhz ones, running disk test only pulled ~11 watts ( ac no less ) .. they are very low power consumption computers

    figure 20 watts total x # hours run, thats your watt/hours needed .. I'll leave the regular verbose posters to fill in the blanks on battery/charge controller/panel for above PC
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Solar Powered PC

    kf,

    The size of the PV module and battery will depend upon your local insolation. Accordingly, we need to know more about where you live. If possible, please select a location from the following list. You may need to seach nearby states for a location close to you.

    See: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/mon2/state.html

    More verbosity later,
    Jim / crewzer
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Solar Powered PC

    simply 60w at 12v translates into a 5amp draw. if you need this on for 24hrs that is 24x 5a=120ah. now you don't want to exceed 50% of battery capacity so this doubles the capacity to 240ah and will be the minimum size battery used.
    the charge needed into the batteries will be 120ah, but it does depend on where you are and the season that determines how much full sun you'll receive in order to determine how much pv is needed. for example, if you get 5 hrs of full sun it will be 120ah/5hrs=24amps. to overcome losses and efficiency factors you should up this somewhat by dividing by .75 or .8 giving a pv setup of 30-32amps stc. naturally if you don't run this for 24hrs it will save greatly on the rest of the system requirements and figure them the same way.
  • mike95490mike95490 Posts: 7,915Solar Expert ✭✭✭✭
    Re: Solar Powered PC
    This machine is going to be ran headless so powering a monitor will not be an issue. I figure after I install a 1GB stick of ram an optical drive and a laptop drive the entire setup shouldnt consume more than 50-60w total.

    What about wireless ?? What's it talking to ??

    Configure power saving modes, to spin the HDD down after 10 minutes.

    Consider a couple GB of USB Flash Drive, versions labeled "Ready Boost" should be VERY robust and last for millions of R/W cycles Do you need more that a couple GB of HDD space, many newer BIOS will boot from a USB flash drive.

    Consider pulling the optical drive, after the PC is configured, I've heard they alone can suck 20 watts idle. Laptop CD/DVD's completely power down, but IDE CD/DVD drives have a lot of idle draw.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • System2System2 Posts: 6,290 admin
    Re: Solar Powered PC

    I live outside Indianapolis IN. I was planning on running 24x7 but if that is going to require over 100 watts in panels then I think I will find some sort of schedule to only run the PC during peak hours or something.....
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Solar Powered PC

    Assuming a 20 W net load 24 hours/day, the battery will need to supply 20 W x 24 hours/day = 480 Whr/day.

    Assuming a nominal 12 V battery, that’s 40 Ah/day.

    Assuming 3 days of autonomy (no Sun) and not letting the battery discharge below 50% SOC, you’ll need a 12 V battery rated at 240 Ah. That would be a size 8D battery.

    Assuming the battery’s coulombic efficiency is 98% (Ah out/Ah in; a VRLA battery), you’ll need to generate an average of 41 Ah/day.

    Indy’s worst average month (December) for insolation on a south-facing module tilted at latitude + 15 degrees (~55 degrees) is 2.7 hours/day of “full” Sun. To generate 44.5 Ah/day, you’ll need a module rated at 15.2 A.

    As a practical matter, this means a “12 V” array rated for at least ~263 W STC, and 300 W STC would likely be better. A candidate charge controller would be the MorningStar PS-30M.

    And, you’ll have to clean the snow from the PV modules in the winter. ;)


    HTH,
    Jim / crewzer
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