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making a 12v to 240v power inverter

Discussion in 'Alternative Energy' started by jahan002, Apr 26, 2009.

  1. jahan002

    jahan002 New Member

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    first of all i will like o that this my first post and that i am a novice when it comes to electronic.

    I purchased a solar panel which as the following spec:
    Optimum working voltage of :- 17.5V
    Optimum working current of:- 260mA
    Peak power output:- 4.8W

    I want create an inverter that will convert the power from the solar into 240V
    i have a UPS which i can get some hardware from. thanks in advance.
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Just use the panel to charge a battery, the inverter runs from the battery.

    However, it's such a tiny panel, what do you expect to run from it?.
     
  3. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Its very low power can charge a battery that will blink a 10W light bulb one time each week.
     
  4. dave

    Dave New Member

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  5. jahan002

    jahan002 New Member

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    thank you for the reply

    i will tria and get a more powerfull panel
     
  6. jahan002

    jahan002 New Member

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    i am looking forward to powering my laptop with it.
     
  7. mneary

    mneary New Member

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    After a sunny 8-hour day of charging you will be lucky to get 15 minutes of laptop usage.
     
  8. SPDCHK

    SPDCHK Member

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    Laptops consume in the region of 50W PLUS power.

    Power Out = Power In - Losses.

    You will need at the least 10 times the panels you’ve mentioned.

    And remember, even though sunlight is for free, everything else will come at a cost. I don't have the correct figures, but I do not believe (unless it's a unit designed by someone like TCMTECH), that you will get efficiency of greater that 60% from a home made inverter, so that will make the count of 10 times panels also not enough.

    4.5W will be enough to power a LED flash light though. :D
     
    Last edited: Apr 26, 2009
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  9. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I'd say your about right on the 60% efficiency range.
    If you were to use modern schematics and good modern day parts with designs based on actual data sheet information related to those parts, A low frequency iron core transformer based inverter could conceivably hit 85% efficiency.
    But you would need a good quality transformer that has an honest 90% or higher efficiency. And still that would require the control circuits and switching devices to stay under 5% total loss.
    I honestly could not guarantee that number either (and make an actual clean sine wave any way)!
    75 -80% would be more realistic.
    The low end non sine wave HF inverters run about 85% on average and the good high efficiency ones do have ratings above 90% now.

    But given the tiny solar panels actual output I would still agree with everyone else and charge a battery with it and use the accumulated power.
     
    Last edited: Apr 27, 2009
  10. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I rethought it and at that low of available power I doubt you could even hit much higher than 35% efficiency realistically.
    The control circuit and switching devices would consume about 1.5 watts. The step up transformer (iron Core wall power pack type) at that small of size is going to be at best 50% efficient.
    Given 4.8 - 1.5 = 3.3 3.3 * 50% = 1.65 watts. 1.65/4.8 = 34% efficiency.:(

    1.65 watts at 240 volts is around .0069 amps! You might run a mini neon indicator light to tell you your inverter is on but then you would have no power left to work with! :p

    Maybe make up a set of mini padles and use it to restart a hampsters heart! or electrocute some bugs! :D

    Sorry to rain on your parade. At least now you have some idea of what your working with!

    However with 4.8 watts available at 17.5 volts or less you have loads of small electronic devices you could build or power with it! :)
     
  11. Thunderchild

    Thunderchild New Member

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    good luck, I have 2 X 20 W panels and I make enough iin a day to run one LCD computer monitor. if your going to run a laptop off it why not get a laptop power supply for use in a car so that it takes the power straight from the battery. you are proposing to charge a car battery and in this process not all of the power will result in a charged battery, then you are going to conver the 12 V DC to 240 V AC and in this process you will loose 10-15 % of the power, you will then reconvert 240 V AC down to the laptops voltage at DC and loose a further 15 % so by the time you finish you have about 75 % of what you started with. whereas if you directly use the battery to power a laptop power supply you cut out one stage and recover more power.
     
  12. electronrancher

    electronrancher New Member

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    A laptop input is only 14-20v DC. So to convert your DC to 240v AC and back again is a big waste.

    I'd suggest using a buck-boost DC-DC converter to convert that varying DC panel voltage into a fixed 19v (for example) to charge your laptop. You should get 85% at very worst case.
     
    Last edited: Apr 28, 2009
  13. mneary

    mneary New Member

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    Search eBay using keywords auto laptop power and you will see about 131 hits which offer devices of this kind, starting at about US$18. I bought one and I'm extremely happy with it.

    Or you could design and build one.
     
  14. Hero999

    Hero999 Banned

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    A single 12V panel will probably be able to charge three 6V SLAs in series.

    The 12V panels I have put out 26V each and their maximum power rating is taken at 17.5V.
     
  15. Thunderchild

    Thunderchild New Member

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    in which case they can't charge 18 volts of battery as you need 20-21 volts and you have maximum output at 17.5 volts best thing is use 12 volts and a chargin regulator
     

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