DIY Solar panel setup on a budget

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

  1. OP
    OP
    Mathuisella

    Mathuisella Member

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    in your gearbox...grindin
    nice :D

    How goes the battery storage in regards to night time ?
     
  2. Recharge

    Recharge Member

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    so, what I learned today. a 10w 12v panel can give a surprising jolt when you're messing with electrolysis rust removal...
    haha I jumped :lol::shock:
     
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  3. rainwulf

    rainwulf Member

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    It will be 18 volts open circuit, and yea with wet fingers and/or cuts that could be dangerous.
     
  4. rainwulf

    rainwulf Member

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    Pretty good actually, i am running in peak shift mode, basically charging during the day and using that power in the evening, and then for the rest of the night drawing around 10 amps until morning.

    Batteries are getting tired though...
     
  5. OP
    OP
    Mathuisella

    Mathuisella Member

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    PM sent :) about batteries
     
  6. miicah

    miicah Member

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    How useful are old UPS batteries? Does anyone have a guide/link that outlines what I should be looking for or avoiding?
     
  7. vk2fro

    vk2fro Member

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    The best UPS batteries to get are the ones for backing up fire suppression systems. They hardly see any load as they are there to take over if the power fails during a fire. So they spend most of their lives on float, with a yearly or bi yearly test of the system (apart from the 2 weekly test that some ups' do). This is (from memory I could be wrong) where my bank came from (or a similar system that barely placed any load on the batteries). They have been doing well, and provide me with 2 days worth of power to the lounge room and fridge.

    on a different note, I got my Victron gear back and finally convinced my landlord to let me put up my panels. I had a mate of mine offer to put them up for me (he does solar installs) if I provide all the hardware, which he will give me a list of items to buy including the racking and disconnects and other tidbits. So I guess hanging onto my batteries and panels for a little while was a good idea. As for the Victron gear, my friend who bought it was happy to sell it back to me as he decided not to go DIY, but instead of giving him money, I will trade him two 300W Csuns and 3 55Ah batteries and a spare charge controller to run his repeater site. As the panels will be going on a shed, and the batteries living inside that shed, we don't need to jump through any hoops to get the repeater running off solar.

    Regarding my system, we will be running my 8 panels in series strings of 2, and then paralleling them up. I know I have a mate putting the system up, but does he just link the four strings of 2 panels (so now he'll have 8 sets of MC4's with about 80 volts across them) then plug the 4 strings into the combiner box, (which would result in around 80V at 20A on the output side). And is there a fuse between each pair of panels - if so I'd like to get more fuses to have on hand in case of one blowing.
     
  8. rainwulf

    rainwulf Member

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    Fuses on the panels wont blow. The panels can't provide more then their rated current.
     
  9. Symon

    Symon (Plugging your Socket)

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    The fuses are there in case a panel fails and goes short circuit. They prevent the good panels in parallel from feeding into the shorted panel.
     
  10. RobRoySyd

    RobRoySyd Member

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    Even if a panel fails SC the blocking diode will prevent current flowing into it.
     
  11. rainwulf

    rainwulf Member

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    I really don't think a panel could fail and go short circuit... i honestly don't think that's even possible. That would mean each cell would short circuit? And if it does.. what would the fuses protect against? The panel is already failed.
     
  12. Symon

    Symon (Plugging your Socket)

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    Assuming one is fitted, they aren't always.

    A solar cell can fail open or short. The fuse won't stop the panel failing, but it will stop it, or the wiring, catching fire.

    Plenty of photos out there of arrays burnt to a crisp.
     
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  13. Privatteer

    Privatteer Member

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    Wrong, If there is more than 2 parallel strings.
    If there is 3 8Amp strings for example that is a possible 16A into a fault.
     
  14. rainwulf

    rainwulf Member

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    Yoinks, i didn't even think about that!! Duh i should know better!
     
  15. RobRoySyd

    RobRoySyd Member

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    As you've reminded us previously fuses don't protect against every way electrical energy can start a fire. Solar panels don't need failure for things to go wrong.
    https://www.pveducation.org/pvcdrom/modules/hot-spot-heating

    On the upside thankfully here in Au the common roofing materials do provide a fire barrier.
     
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  16. Recharge

    Recharge Member

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    might be of interest to some.
     
  17. Recharge

    Recharge Member

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    this looks like a very nice system! excessive cost for all the battery holders, but if you don't want to make packs, it's as simple as it can get.
     
  18. OP
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    Mathuisella

    Mathuisella Member

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    After all that, i think it may be better to go with lto ?
     
  19. Recharge

    Recharge Member

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    quite possibly. I guess it all depends on how you want it set up and how much money you have to burn.
     

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