how to connect solar panel to where

Discussion in 'The Projects Forum' started by ketanco, Jul 29, 2014.

  1. ketanco

    Thread Starter New Member

    Jul 29, 2014
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    sorry for my ignorance, as i am just starting out in electronics and it is my first post here, so hi everyone...

    I am interested in buying a solar panel and connecting it to somewhere, so that it helps saveing or producing electricty in my dads field house in a foreign country.

    so whatever standard systems in the US will not apply. I will buy a solar panel, take it there and connect it somewhere.

    so what kind of panel i must buy? it must be something i will be able to carry in my luggage, nothing so big. flexible panels would make more sense or what? something i can buy from amazon etc... or where you suggest?

    also, how do i connect the panel to where? what would make most sense? connecting to a lamp? to the main electrical of the house? to charge a battery which can then power other things?

    there are frequent power outages there. would charging a battery with it make the most sense?
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Yes. Forget about tying into anything that uses line power. That's a difficult and potentially dangerous project for even an experienced person.

    The only exception to the battery would be something that you want to run only in sunlight. Maybe a small water recirculation pump or a ventilation van for a small building or car cab. If you want lighting, then the battery makes obvious sense. Maybe an LED security lamp, with or without a motion detector? Cellphone or radio charger?

    Point is, think small until you have more experience and understand the limitations. There's a tendency of beginners to greatly over-estimate what solar panels can do.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Anything you can carry in luggage will not be worth the effort.
     
  4. MrChips

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    The only use I can think of for a small 5W solar panel (12" x 12"), is to trickle charge an RV/marine 12V lead acid battery or a 12V sealed lead acid battery to be used for emergency LED lighting or for powering a DC-to-AC inverter.
     
  5. ketanco

    Thread Starter New Member

    Jul 29, 2014
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    ok so would this be the battery type i would search for, to connect my solar panel? or what type of battery should i search?
     
  6. MrChips

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    I think your approach is backwards. First decide what needs to be powered either at night or during a power blackout. Then figure out the power requirements and the size and type of battery and/or power inverter.
     
  7. wayneh

    Expert

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    Ditto. Having a technology looking for an application is so much less powerful than recognizing a need and filling it with the right technology. A windmill to pump water might be a far better project, for example. Or a water filter to make potable. Whatever.

    My daughter spent some time helping folks in Haiti, and one of the things the Haitians complained about is that the Americans come in and ask where to spend money. The Haitians want to learn to fish, not be handed a fish. Or how to install and operate a solar power installation, not just be given one. They know that they need to build an infrastructure to sustain themselves, not just live off handouts. I'm not sure their goal can ever be realized, but it's noble.
     
  8. Johann

    Senior Member

    Nov 27, 2006
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    A good reason to have solar, is to run a transistor radio with some good music to listen to - free of charge!
     
  9. ketanco

    Thread Starter New Member

    Jul 29, 2014
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    ok so all i want is, that this solar panel charge the battery, which would power 1-2 lamps, each may be 60 watts.

    now is it specific enough? :)
     
  10. MrChips

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    Sorry, not quite.
    You have to do some basic energy calculations, i.e. match your input and output.

    How many hours do you want to draw 60 watts?
    What is the wattage of your solar panel?
    How many hours of full sunlight do you expect to harvest?
    Factor in about 20% energy loss.
     
    Last edited: Aug 1, 2014
  11. wayneh

    Expert

    Sep 9, 2010
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    If you use CFL or LED lighting equivalent to 120W of incandescent lighting, you might have a chance. But answers to the questions above will make it clear.
     
  12. Johann

    Senior Member

    Nov 27, 2006
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    Follow advice given by MrChips.

    Furthermore, when you run off solar, you want to conserve power, so using two 60W lamps would be a waste of power and your battery and solar panel capacity (and inverter etc) would have to match and may become unnecessarily expensive.

    Start with your needs and work back to the hardware required to satisfy the needs.
     
  13. ketanco

    Thread Starter New Member

    Jul 29, 2014
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    ok i see. so lets assume that for a 60W lamp, I want to run it for 5 hours.

    this means, a panel of 30 watts must harvest energy for 15 x 1.20 hours correct? is that how it works? and if i connect two panels (in parallel or series?) to the battery, then this is half the time? is it straghtforward like this? I remember from physics that P = VI. so in theory are we equating both VI to each other?
     
  14. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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  15. wayneh

    Expert

    Sep 9, 2010
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    I get 5hr x 60W= 300W•hr. That would be 10 hours from the 30W panel in full sun, more under clouds, plus whatever loss factor you want. I think 20% (12 hours) is a bare minimum loss and would not be surprised to see a 50% loss overall (20 hours).

    Adding panels, whether in series or parallel, will indeed supply more power and reduce the needed charge time. The supporting electronics must support an efficient capture and storage of that power. That consideration can dictate whether series or parallel is a better choice.
     
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