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experimental set up ?

Discussion in 'Photovoltaics' started by [email protected], Oct 20, 2003.

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  1. Guest

    how many panels would i need to run my tv 85.watts dvd,12
    watts ,vcr 12 watts, webtv,12 watts 1 hrs, or 2 hrs. a day
    lets say 5 days a week sometimes 7 i am from alabama
    so we get a lot of sun and also how much would it cost
     
  2. George Ghio

    George Ghio Guest

    You will need to be a bit mor specifec. Each item for how long / day

    George
     
  3. Guest

    What part of Alabama? I am in Mobile.
    I have a solar setup and might be able tohelp if you are close.
    YOu have to be more specific in your operating times for someone to give
    you a acurate estimate. How long will each item be on for how many days.
    Also how many days do you want to be able to operate if it is cloudy for
    a couple of days?
    Offgridman
     
  4. Well, as others have said, you might need to get a bit more
    specific to get accurate estimates. That said, I think there
    is enough to give you an idea.

    First you need to know how much electricity you need.
    Add up the wattage's and multiply by the hours you want
    to use them to get watt-hours (or kwh). Yours add up
    to 85+12+12+12= 121 watts x 2 hours = 242 watt-hours.

    Now, you'll need more than this amount of electricity
    a day because you lose some at all stages. Batteries
    only put out, say, 80% of the energy you put into them,
    inverters only 80% to 90%. In your case you can figure
    242wh/.80/.80 = 378 watt-hours.

    Then you need to know how much sunlight you get there.
    NREL can help a little there.
    http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/
    http://rredc.nrel.gov/solar/calculators/PVWATTS/

    Most places in the United States get at least 3 to 4
    kwh/m^2/day (just think of it as 'sun hours'). If you
    want to know many much PV panel to buy then divide
    the total watt-hours required by the 'sun hours'.
    This would be, say, 378/3 = 126 watts.

    Panels come in all different sizes and they are sold
    by their STC rated wattages. You should only figure
    on 80% of this in the real world. That is, a 100W
    panel only should be expected to produce 80W. It may
    produce more for a decade or two but they do degrade.
    You can figure anywhere from $3.50 to $5.00 an STC
    watt when buying the panels themselves and then
    perhaps another dollar or two for batteries and
    everything else.

    This means you'll need (126W/.80) 158 watts of PV
    costing some (158w x $7) $1106.

    Now, you could probably reduce that somewhat in any
    number of ways but this gives you an idea of the
    kind of ballpark you'll be playing in.

    Anthony
     
  5. Guest

    thanks anthony u help me out. u gave me a good idea on cost.and panels i
    need take care
     
  6. Guest

    you say another dollar or two . what is the cheapest he could get a
    battery and inverter and control unit for ?
     
  7. Unlike panels, there are a very wide range of options for the
    batteries, inverter and charge controllers.

    The cheapest way possible is to scavenge parts, batteries
    and so forth from junk yards, trash and recyclers and
    then build your own circuits, mounts and trackers.

    In this case, he needs some 242 wh/day. If he limits himself
    to DC then his only losses are in the battery so he'll need
    some (242/.80) 302 wh/day from the panels. With a tracker
    he might get some 4 sun-hours a day so he'll need about
    76 watts of PV. With mirrors he could double the output of
    those panels without risking too much damage and cut that
    down to 38 watts. He could perhaps purchase dead yard lights
    for something like $.50 to $1 and most run about half a watt.
    The whole thing might be put together for $100 and a lot of
    hunting for parts. Maybe less if he fixes a few of the yard
    lights (usually just need a new battery) and sells them or
    put the cells themselves up for sale for $10/watt.

    Anthony
     
  8. Guest

    you can get a 38 watts panel for $100 ?
     
  9. Those solar powered yard lights typically have lifespans of
    only a few years. The parts that fail are usually not the PV
    cells (which are in the half watt range). PV cells can last
    many decades while batteries (especially outside in the sun)
    usually won't. Many people simply throw these things away
    when they stop working. If you advertise that you are willing
    to purchase non-working solar powered equipment then perhaps
    you could pick them up for nearly nothing. You would still
    need to remove the PV cells and wire them into an array
    yourself.

    Anthony
     
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