DIY Solar panel setup on a budget

Discussion in 'Hobby Engineering' started by Mathuisella, Oct 15, 2013.

  1. Mathuisella

    Mathuisella Member

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    Hi there, well i've been interested in my own solar setup for a while as i always dread the electricity bill as many here would also.

    Anyways, earlier i bought a 180watt panel, but it didn't suit my needs, so i bought 2*250watt panels and it's "getting there"


    so, i have the panels mounted up into the sun, the cable i'm using is a 100metre roll of 240v 15A copper cable that literally fell off the back of a truck at a set of lights as it raced through the yellow/orange/amber.... I behind it stopped for the red and reaped the rewards picking up the roll to be used for many an electronic project :D

    so, the panels are 250watt, 24v wired in parallel to a charge controller then to a battery bank of salvaged car batteries. ( 2*12V truck batteries) and from there to a 24 to 240 Pure sine wave inverter


    Costs so far.

    Solar panels > $500+ shipping

    Y adapter for solar panels in parallel > $ 20

    MC4 adapters > $10

    Roll of cable > $free

    Charge controller > $30, but faulty :( going to buy a new one

    Inverter > $220

    Batteries.... $120... So far

    2* Trojan 160AH batteries $50 each
    2*12v 4v4/truck batteries..... $10 each from the wreckers in "unknown condition" took a chance, one seems to be ok, the other is toast
    1*12v 4x4 truck battery..... Found during council cleanup free :D with a very nervous ride with it on the bike home....

    Tonight after i got home with the "free" battery i put it into the system and ran my 30" dell monitor from it drawing 250watts for approx 90 minutes before the low voltage alarm sounded on the inverter, which i suspected was because the battery i picked up didn't have much of a charge left in her before tossed onto the curb...


    I'll let the system charge tomorrow from the panels and see how we go. Panels should have a good charge after 8 hours of sunlight at 15 amps ( 500watts )

    anyways, my setups design

    Click to view full size!
     
    Last edited: Oct 15, 2013
  2. @rt

    @rt Member

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    I'll leave some batteries on my kurb if you want.
    They are alos in unknown condition (to you) :)

    Nice. Solar is always fun... feels like you're cheating the man :)
     
  3. deejeta

    deejeta Member

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    Cool little project :thumbup: .If you invest in a good charger you can bring almost dead batteries back to a reasonable healthy state as long as the cells arent physically damaged. There are some quite good desulphating chargers that work wonders. Seem to work better than a brute force charge.
     
  4. Fishface

    Fishface Member

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    Car and truck batteries are not designed to be used for deep discharge applications, they will have a short life when used in that way.

    The system as you have described it will be a useful learning tool however the money it saves you in power bills will be miniscule.
     
  5. rainwulf

    rainwulf Member

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    Here are some pics of my current project.

    1200 AH of storage (100 percent DOD though, so never would use it that far)
    6 Deep Cycle Storage cells (1200 charges at 50 percent DOD)
    200 ah each.

    Runs my mail file server (xeon, 16 drives) 24/7
    13 80 watt panels in two banks (still purchasing more)

    Currrently showing 45 amps into the bank and 15 amps out of the bank to the main inverter.

    the 12 volt rail also runs some LED halogens and strip lights in my garage.

    The MPPT controllers i dont think work very well, im going to be purchasing some better quality ones when i get some free cash, i have over a kilowatt of panels on the roof but i rarely see over 55 amps of charge at 13.8 volts which is just shy of 760 watts. They are either not MPPTracking properly, or just dont go into MPPT mode at all, because the panel voltages drop to about 1 volt over battery voltage, which is NOT how MPPT works.




    [​IMG]
    Overview from the left.
    Two inverters for failover. (manual)
    Main circuit breaker under the middle inverter.
    current consumption meter is the led display on the left.
    main bank voltage is the led display in the middle bottom.
    charge current meter next to the two solar charge converters. (MPPT)
    and the blue thing is an 8 amp maintenance 5 step charger for rainy days and battery top off charge when doing electrolyte checks.
    Bottles of deionised water for top up and just visible is the hydrometer.
    The grey box is a little gear pump i use to drop of the cells with water. Less spillage.
    The white powder is a test to see if crystaline cat litter is effective at neautralising battery acid.


    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
    Last edited: Oct 15, 2013
  6. @rt

    @rt Member

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    Since the OP has only mentioned a single controller,
    it sounds like dud batteries have gone into the mix with good ones.
     
  7. Mathuisella

    Mathuisella Member

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    yeah, the Lead acid battery i got works well. However the others have been Calcium batteries which kinda suck.

    My charge controller says it's for lead acid, so unsure how it will go.

    i'll pickup another lead acid soon :)

    edit: > rain... you make my little project..... haha..... :'(

    edit 2 >

    oh I know all too well that the car/truck batteries won't fair too well in the medium to long term of it all... But it was cheap and i wanted to see something "work" :D I want to get some deep cycles soon :)

    edit 3 > Rain, do you feel like offloading some of your 1200AH to me ? i'm also in brissy. and perhaps you could come and checkout my setup and give a few pointers.... I'm doing this on such a uni student budget and ghetto'ness it's crazy....
     
    Last edited: Oct 15, 2013
  8. rainwulf

    rainwulf Member

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    well i tell you something i may be in a position to offload a LOT of ah soon. will be getting back to you about that.

    where in bris are you?
     
  9. Mathuisella

    Mathuisella Member

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    about 10 minutes NW of the CBD :)

    I got myself 2x
    http://www.trojanbattery.com/products/t-127512v.aspx

    today :)

    they are "reconditioned" and set me back $50 each
     
  10. Phido

    Phido Member

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    Interesting setup rain. Are those scorch marks on your cables?
    I have 1000w with a regular controller and see over 800 w regularly in syd.
     
  11. rainwulf

    rainwulf Member

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    From the flame from the soldering iron thats all.

    nothing gets that hot thats for sure, and i regularily check all connections for heat generation which would indicate high resistance.

    I am in albany creek OP.
     
  12. Mathuisella

    Mathuisella Member

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    ah nice. you're about a 10 minute drive north from me :)

    my panels say that they are 250 watts, so. 30V @ 8.3amps for each panel.

    So i should be seeing something along the lines of 16 amps as they are in parallel :)


    however at the controller i'm measuring 6 amps @ 27 volts :(

    Here is the wire/cable i'm using Each length of wire is doubled up to help stave off losses


    Click to view full size!




    I know this is my "weak link" and where i shall be experiencing losses :(

    I can't wait until my new charge controller gets here as it has an LCD screen and should show me what's going on in real time :) I've also ordered a "caliper" multimeter so i can see the amps running through each line.
     
    Last edited: Oct 16, 2013
  13. Mathuisella

    Mathuisella Member

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    ok, i tripled up the wire from the panels to the controller and for the connection from the panels to the 3 way wire split run i put in some 60Amp rated cable and wire connector.


    Click to view full size!
     
  14. Mathuisella

    Mathuisella Member

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    upgraded the above connection to 5 strands :) so a total of 7.5mm^2 of copper from the panels to the controller. ( 0.2Vdrop along the 15metre run of cables )

    New controller arrived and it's much better than the previous one. It lets me set up voltage drain cut off and shows how much amperage is coming into the panels and also being drained by the load :)

    http://www.ebay.com.au/itm/30A-Sola.../140938384259?pt=AU_Solar&hash=item20d0951383
     
    Last edited: Oct 18, 2013
  15. Mathuisella

    Mathuisella Member

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    Hating todays cloudy as fuck day :(

    Need more sunlight.... only getting 30 watts out of the panels.
     
  16. mtma

    mtma Member

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    Realities of on-land solar power :(
     
  17. Mathuisella

    Mathuisella Member

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  18. Mathuisella

    Mathuisella Member

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    so in the above pictures my setup is the following

    2*250watt panels ( parallel ) ( peak ) @ 24v ( 32v input to the controller and 36v open circuit "thevenin Voltage" ) with a 0.2vDrop

    Solar 30 Charge controller ( i cannot recommend this enough, it's a fantastic controller for the price if anyone's on a budget, but wants one with a display that will show and let you configure everything )

    trojan 1260 Deep cycle batteries x2 - reconditioned ( picked these up for $50 each )

    Using a minimum of 7.5mm^2 copper cable which is good for much more than my panels can output

    24 to 240V 600W, 1200W peakpure sinewave inverter. Picked this up from ebay from a sydney based company and it's been fantastic


    I'm finding that i need another panel or two and a few more batteries :(

    drawing 250-350 watts i get 3-4 hours on the batteries before the Voltage drops to 23.8Volts and the auto-cut off kicks in to prevent over discharge.

    Anyway. I'm going to let the batteries charge for a couple of days ( i get about 5 hours of good sun per day) so i should get a nice solid charge up to the battery's 100% level and see how we go.
     
  19. hairy

    hairy Member

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    so can you guys do me a favour (im looking at a small setup for my shed).
    how much did the whole shebang cost and where did you source the parts from?
    individual items would be nice just ballpark.
     
  20. Mathuisella

    Mathuisella Member

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    sure.

    Panels are Approx $1 per watt.

    I use a 24v setup as my panels are 24v and higher the voltage the better for less line loss.

    Batteries i got from a battery place on the south side of Brisbane that deal in solar setups.

    the cable i already had so it was free.

    charge controller was a bargain on Ebay, but i want a new one :p so if you want one cheap ask me :D

    so here's a rundown

    Panels $500 for 500 watts ( 2*250 panels )
    batteries $100 for 150Ah @ 24v ( Real deep cycles, but reconditioned and probably only good for 100AH)
    charge controller $50
    random bits and stuff $20 from jaycar
    24 to 240v pure sinewave inverter $200


    Batteries
    http://www.battery-central.com.au/

    Charge controller
    http://www.ebay.com.au/itm/140938384259?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

    Inverter
    http://www.ebay.com.au/itm/251243833923?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
     

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