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Solar power kit - need expert suggestions

Discussion in 'Survival/Preparedness Forum' started by MIJoe, Aug 17, 2011.

  1. MIJoe

    MIJoe

    104
    0
    Jun 15, 2002
    FL
    Greetings.

    I would like to put together a solar power charging kit (for 12V batteries).

    My knowledge on solar anything is very limited...other than the solar panel(s) and battery(ies), what else is needed?

    Does somewhat have a complete list of everything needed?

    Thanks!

    Joe
     
  2. More than likely, a charge controller to go between the panels and the battery.

    A parts list is easy, the sizing of the system and of those parts is not. The real question is, what are you planning to do with this?



    Cliff notes version:
    Depending on where you are in the hemisphere and time of year, you'll only get 5 hours of sunlight a day on a fixed panel. If you're still in Florida, that's a good thing


    So let's say you have an 80 watt panel, which puts out about 4.5 amps
    4.5amps x 5 hours = 22.5 total amp hours.

    Now, 22.5/ 24 hours in the day means you get about 900ma of usable continous power.


    Your battery should be minimum 4 times, preferably 10 times the capacity of the maximum output of your panel. So if you have an 80 watt panel that puts out 4.5 amps, you should have at least a 50 amp hour battery.



    There's a LOT more involved, but that's the bare basics
     

  3. MIJoe

    MIJoe

    104
    0
    Jun 15, 2002
    FL
    Ric0123

    Thanks for your helpful comments - I really need to read up on solar equipment.

    Intended use would be during times when power is not available (hurricanes, etc), so I can:

    1. Run a small (car travel type) fridge, mostly to keep insuline for family member

    2. Couple of lights

    3. Charge AA batteries for flashlights, FRS radios, notebook

    Appreciate your suggestions

    Joe
     
  4. BMH

    BMH Lifetime Member

    835
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    Feb 26, 2007
    Alaska
  5. quake

    quake Millennium Member

    4,142
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    Aug 4, 1999
    Arkansas, USA
    This.

    This is the inside of a home-made power box that usually rides in our box trailer for lights, chargers, etc.
    [​IMG]

    Voltage from the panels comes in to the silver connector (on the left in the pic), to the charge controller, then to the batteries and the outlet ports on the right in the pic.

    Outside (right side), three normal lighter-type outlets provide generic power outlets, and a streamlight strion charger base is hardwired in to provide an always-charged flashlight.
    [​IMG]


    Battery cost will be an issue that will vary greatly, and it's worth getting creative with them. These pics are old, from when I first made the box; probably 2005 or so. Since then I've had to replace the batteries once - they're in a very hostile environment; a metal enclosed box trailer that gets well into the 130's-140's in the summer and freezing in the winter - so a shortened 4-5 year lifespan is all I'm likely to get no matter what I try. One thing I DID do, was to use different batteries the second go-round. The original two 18-ah batteries provided 36ah of 12vdc power, and cost me (wholesale) around $58 apiece. Instead, I replaced them with four 7ah batteries that cost $13 each. Those provide slightly less capacity (28ah vs the original 36ah) but total cost is only $52 instead of $116. Put another way, using a larger quantity of smaller batteries dropped my storage cost from $3.22 per ah, down to $1.86 per ah; more than a 40% cost reduction, in the one part of the system that's going to have to be repeatedly replaced.

    When I built it, I knew about what power capacity I wanted, and bought the two batteries that got me that the simplest way possible while still fitting in a given space. I'm very glad I actually took the time to think it thru on the second set - any time a person can reduce maintenance cost by almost half, that's a good thing.
     
  6. poodleshooter1

    poodleshooter1

    1,844
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    May 3, 2005
    What about wind power? Where I live the sun is rarely seen, so wind power might be a better alternative and one that you have not considered.
     
  7. Bolster

    Bolster Not Ready Yet!

    1,149
    1
    Jul 23, 2011
    State of Stupidity
    To answer your question: No, nobody has a complete list needed, because you are looking for a custom solution (and other than your basic 12v solar trickle charger, almost all solar IS a custom solution). As has been posted, you work backwards from your energy needs, and build around that.

    Solar is not an "off the shelf" sort of thing. You have to load a lot of arcane knowledge in your head, do calculations, engineer it, and only then do you know what you should buy and how much. Solar is very "chicken or egg" type of stuff. It's like trying to solve an algebra problem where most of the variables are unknown, so a lot of guessing goes into the equation. Who can answer, with confidence, the question: "How much energy do you need?" Yet that's where all the calculations start. So you take your best guess at a number and go from there.

    Small subsistance style cabins and small, frugal homes may work on 450-500 watt systems (usually 3x150w panels), so there's a start. A 450 watt cabin can make do with maybe 4 x 350 amp hour batteries. (An off-grid home needs maybe 1200-3800 watt systems to be comfortable. )

    Your energy needs are small until you get to the refrigerator, then they balloon in size. I have a friend who has a solar powered sailboat (common these days) and the fridge was his biggest energy hog by far. He had to toss it, and drink wine instead of beer.

    So the place for you to start is likely a book on going solar, of which there are many in libraries. Libraries LOVE these sorts of "green" books (pushing the secular religion of environmentalism) so pretty much any library will be well stocked on this topic.

    I would like to build a small solar PV system, but am waiting to see if Obama gets voted out first. I don't want to become a statistic that props up Obama, as in, "Look at all these people who went solar under Obama." So I plan to buy late 2012 or early 2013. Call it "passive solar resistance" if you will.
     
    Last edited: Aug 19, 2011
  8. Syclone538

    Syclone538

    2,086
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    Jan 8, 2006
  9. MIJoe

    MIJoe

    104
    0
    Jun 15, 2002
    FL
    Thanks for all comments.
    Need to do my homework on solar power.
    Joe
     
  10. quake

    quake Millennium Member

    4,142
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    Aug 4, 1999
    Arkansas, USA
    That tsc unit seems like an ok deal - not great or terrible either one. Looks like it doesn't have a battery with it, so you'd have to buy that separate or else use this solely for charging batteries you already do have; car batteries, etc.
     
    Last edited: Aug 20, 2011
  11. Carry16

    Carry16

    579
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    Sep 7, 2004
    SW Missouri
    deleted
     
    Last edited: Aug 20, 2011
  12. Aceman

    Aceman

    6,988
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    Nov 30, 2008
    Tampa
    Run a fridge? Heck - I don't have solar for my iPhone yet!

    Great idea though. Way better than a generator IMO.
     
  13. kirgi08

    kirgi08 Watcher. Silver Member

    35,275
    4,155
    Jun 4, 2007
    Acme proving grounds.
    You lose a lot of juice in line transmission,the farther the batts are away from the source ect.'08.

    LG-1 can answer this better than I.
     
  14. emt1581

    emt1581 Curious Member

    19,885
    2
    Oct 17, 2002
    Penn's Woods
    Around here it is rarely sunny AND windy but is usually one or the other.

    What I'd like to do is create a system that will feed a common battery bank but, either simultaneously, automatically select one over the other, or can manually be switched from wind to solar power.

    No clue how to tie both together but the concept seems valid in theory. I figure for $500- $1000 I can have a few car batteries charged year round for some minimal power should there be an outage.

    It's interesting that the tractor supply kit was given a so-so rating. And I'm not sure if it is a better all-around kit or what. But when I made mention of the Harbor Freight kit (which is three times more powerful for 2 times the price) I damn near got my head bit off for even considering such a POS.

    I'm not sure how many watts I should be looking for from a wind turbine and/or solar panels to keep 2-4 12v batteries charged but, as mentioned, from what I've learned a LOT of this stuff is a case by case issue and not cookie cutter in the least except for a few general components that most systems have.

    Good luck and let us know what you decide on. :)

    BTW... Quake...every time I see that box I drool... I want one badly!!

    -Emt1581
     
    Last edited: Aug 25, 2011
  15. Bolster

    Bolster Not Ready Yet!

    1,149
    1
    Jul 23, 2011
    State of Stupidity
    Having both PV and a windmill is highly recommended, for the very reason you state. Chances are one will work when the other doesn't. No switching needed, they feed into the same bank of batteries. You should be thinking in terms of more than one battery, you have decisions to make whether you go 12, 24 or 48 volt...as has been said, all depends on what you intend to use it for, and how far you plan to run the wires (the more volts the longer distance you can run the wires...a wind turbine basically requires higher voltage than 12v, due to length of line run). Your panels always need to output MORE than the battery voltage. So for a 12V system your panels should be giving you maybe 16v.

    What you need are the worksheets in the back of Rex Ewing's book, Power with Nature. Maybe I can scan and send to ya.

    In the meantime here are some rules of thumb:

    - My friend's sailboat, powering radios, lights, navgear, computer, fan, and sometimes a peltier cooler: 180 watts.
    - Often recommended for a 'survivalist' cabin: 450 watts. Could probably run the above and a TV and/or small fridge and/or toaster oven.
    - An offgrid house with all the amenities: 3000 watts or more.

    Since solar panels often come 150w each (at $200-$500 ea), I am considering a 1x150 expandable to a 2-3x150 system running 12 volt, as a "backup" electrical system for running LED lights, recharging radios and batteries, running laptops during outages. Will require probably 2-4 100 amp hour 12v batteries, $200 a pop.

    So for a minimalist PV backup system I'll probably be into it for a $grand$ when it's all said and done.
     
    Last edited: Aug 25, 2011
  16. emt1581

    emt1581 Curious Member

    19,885
    2
    Oct 17, 2002
    Penn's Woods
    I was thinking, why not put the battery bank in a box directly under the wind turbine? So long as I can seal it from rain and snow yet allow for some gas to escape it should work...eventually it'll rot and/or rust though.

    I'm not sure what the difference would be between 12, 24, and 48 volts in terms of running appliances or connecting to outlets. :dunno:

    Those pages would probably be a big help! Thanks

    BTW, I've been watching this guy's videos for a while now... pretty impressive IMO.

    http://www.youtube.com/watch?v=ji7cuASm3ds&feature=related

    -Emt1581
     
  17. Bolster

    Bolster Not Ready Yet!

    1,149
    1
    Jul 23, 2011
    State of Stupidity
    EMT, setting up solar is complicated, so I can't urge you enough to read before you start designing a system in your head. There are very specific rules on battery placement (warm batteries are happier than cold ones, etc), guidelines for what voltage you want, etc, but I can't type it all out here, it's too much, and it's all sitting in a book at your library. Go to the library, check out a book on solar, read it. Don't rely on a few webpages or a webvideo for this one, it's complex enough you need a book. I'll see if I can scan some pages for ya, to get you started. PM incoming.
     
    Last edited: Aug 25, 2011
  18. RED64CJ5

    RED64CJ5

    1,989
    0
    Jul 7, 2003
    These TSC units work fine (I have two) but they have a much shorter lifespan than better panels. Expect 5-7 years out of them versus 20 years on a better quality panel. The TSC kit is actually a good deal when you factor in a decent charge controller. Harbor Freight carries some models but TSC's the most attractive. I'm using this same 15w kit in a semi-permanent installation right now to supply 12v lighting to my horse barn.
     
  19. filthy infidel

    filthy infidel 100% Infidel

    2,490
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    Apr 24, 2007
    North Carolina
    I found some panels on sale and built a kit that would work for a survivalist, but is used as a tool at home. Two 15 watt panels with a charge controller filling a deep cycle battery. The battery powers a 3500 watt inverter via bastardized heavy guage jumper cable wire. I use it to power a variety of tools in the garage, it nicely powers my 1/2 hp rainwater pump to water the yard/garden via rainwater barrels.
     
  20. quake

    quake Millennium Member

    4,142
    67
    Aug 4, 1999
    Arkansas, USA
    For the price of a quarter-sheet of plywood, some screws & hardware, some batteries, a charge-controller and a couple 10-watt attic-vent solar panels from Lowe's and a couple hours' labor, it too can be yours....



    {Billy Mays voice [on]:} But wait! There's more!!! ;)

    The first, smaller one I made, inside a small toolbox. Just a single 12-volt outlet with a rubber dustcover, down on the righthand side in the pic:
    [​IMG]

    Hard to see, but black velcro tabs on the lid mate up to velcro tabs on a simple 12volt fluorescent light. Very handy for portable area light when working on things at night:
    [​IMG]

    Charged by three small deer-feeder solar panels; wired in parallel to keep it at 12 volts. Used a simple 4-wire vehicle-trailer connector for the wiring - three positives and a shared negative. This is the back side of the box, and here as well, velcro on the back of the box mates up with velcro on the backs of the panels to hold them in place:
    [​IMG]

    Inside - a single 7ah battery, the trailer connector harness, and solar panels (held in place with velcro straps). Inline auto-type fuse (on battery positive) protects things. The white plug is a standard 120-to-12volt plug-in transformer which goes into a small charger power supply in the blue box, which then goes to the battery; allowing charging off standard house current:
    [​IMG]

    Misc stuff carried in the box. Generic 12volt power cords, phone charging cord, extra fuses, etc. Power cord with small jumper-cable type clamps lets the box be used to jump start a 4-wheeler, lawnmower, etc. (Don't expect it would do a fullsize vehicle; never tried it.) Also a small 120-volt inverter, but the output on it is very limited. Really only good for small device chargers & such that we may not have a 12volt cord for:
    [​IMG]


    Seriously, just cobble one up some time. You'll likely enjoy it and you'll find all kinds of uses for it once you have it.
     
    Last edited: Aug 27, 2011