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Need help with solar application

  1. May 28, 2010 #1
    First off, I'm just learning the ropes of electricity, solar energy, batteries, wiring batteries in series and parallel, AC, DC, DC to AC Conversion and all that. But I do have the same need of energy as everyone else and a strong interest in finding ways to make my life a little less power plant needy because I have 6 kids and every penny counts. So I'm thinking of ways to start powering each kids room directly solar. I know allot of people start and want to power the whole house from the get go. I'm taking a different more budget able approach my powering one room at a time. But I need some input to get my head wrapped around the project. So for now I will ask advice on my first step of the grand overall idea of the project. ROOM 1.

    Room 1(my room)=

    Qty 1- 60" digital projection TV -- run time 8 hours a day
    Qty 1- 12v WD TV LIVE media player
    Qty 1- Digital Alarm clock

    I have access to a plentiful amount of 12v car batteries. I have 3 pallets of these on hand.

    I have found affordable 12v 150mA solar panels and plan to buy multiple of these to mount in a panel on the roof.

    So this is what I need help with...

    1. How many of these fully charged 12 batteries will I need to have arranged to run the stated time period?
    2. In what way do I need to arrange them -- How many series and parallel?
    3. How many of the 12v 150mA Solar panels will I need to run in parallel in order to charge all the batteries enough to keep up with the demand of the application?
    4.From the batteries to the power strip to plug everything in I will need a DC to AC Inverter right? What should I get that would suite this?

    I figure If I can get my room self reliant then I can do the other rooms one at a time. I'm not worried about lighting and such at the moment. That can remain the same as it is for now.

    Thank you for any of your help in the matter. Looking forward to hear your input.
  2. jcsd
  3. May 29, 2010 #2


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    Science Advisor

    Read the power labels on the various pieces of equipment.
    Look for the number of watts or look for voltage and current.

    Just as a guess, room 1 sounds like 600 watts.

    600 watts at 12 volts is 50 amps. (12 times 50 is 600 watts). If you wanted to do that for 4 hours a day, that would be 200 amp-hours (50 amps times 4 hours).

    The average car battery is capable of about 40 amp hours, so you would need at least 5 of those in parallel.

    150 mA solar panels would not be much use.
    If you wanted to charge the batteries in 8 hours, for 200 amp-hours, you would need to charge at 25 amps. So, you would need 166 of those solar panels. And that is assuming 100% efficiency.

    I suspect that you would never save enough money to pay for the original investment. Lead acid batteries require a lot of maintenance and have to be replaced regularly

    What is killing it is the projection TV. If you just supplied a 10 watt, highly efficient light in each room, you might have a chance of making it viable.
    But mains power is extremely cheap if you have access to it and it is very hard to compete with it financially.

    Money isn't everything, though, and if you just want to learn about solar panels, get one and have a play with it. That is education at its best.
  4. May 29, 2010 #3
    Thank you for your input. I figured the TV would would require allot of power. As for the alarm clock it can stay hooked up to the main....

    So maybe I should focus my first learners project on the motion lighting outside? In the front of the house I have one motion sensor light I like to leave on all the time to scare off dumb burglars that has never heard of motion sensing spot lights.

    The Flood light system in the front uses Two energy saving 23W bulbs. Now, I have access to an insane amount of batteries from batteries like the ones in kids big wheels and pallets and pallets of laptop batteries that the casing is damaged a bit so we cannot sell but the cells are all brand new. What kind of setup would you suggest I start thinking about?

    I can build a weather proof case for batteries and install the solar panels just above on the roof. So with just the two Bulbs that would take me down to a mer 46 watts. I will have them set to 5 mins intervals and i think they only come on usually about 12 times a night for one reason or another. So thats around 1 hour or so usage a night.

    I did try to figure the math on that based on what you told me but I still don't think I have got my mind wrapped around it yet. Soon it will all click and I'll have it as it usually goes.

    So in your opinion what kind of setup would you recommend for this smaller learners project?

    What I'm not sure about is -- (pretty much everything)

    1. What Volt battery I would need and how many run parallel
    2. What volt/amp Solar panel i would need to get
    3. What I need to convert the energy from the battery to the Lighting.

    Thank you once again for your time.
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