USB Solar Tree Charges Your Gadgets

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myromance123

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Aug 17, 2012
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Interesting, I wonder how long it takes to charge though. Also, is sunlight the only viable source of energy it accepts or does normal room lighting work too?
 

saturnus

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[citation][nom]myromance123[/nom]Interesting, I wonder how long it takes to charge though. Also, is sunlight the only viable source of energy it accepts or does normal room lighting work too?[/citation]

In principle any light source works fine. However, the isn't much energy in normal room lighting compared to sunlight. Sunlight has an energy density of roughly 1000W/m2 (100W/sq.ft.).

To calculate the energy density in your room lighting. Just add the wattage all the different bulbs you have in the room, and remember to divide with efficiency of each type. Incandescent lightbulbs are roughly 5% efficient (the rest is heat), fluorescent lightblub are roughly 95% efficient, and LED lightbulbs are roughly 99.8% efficient. Now you have the total energy. Then divide that by the total boundary surface, just calculate all walls, ceiling, and floor surfaces. Then you get the energy density of your room lighting. In most cases it'll be 100s if not 1000s of times less.

Now to finish off. Take the active surface area of the solar cells and multiply the energy density with that and then multiply with the solar cell's efficiency which is typically 14% for crystalline cells and 8% for thin film cells.
 

amk09

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[citation][nom]saturnus[/nom]In principle any light source works fine. However, the isn't much energy in normal room lighting compared to sunlight. Sunlight has an energy density of roughly 1000W/m2 (100W/sq.ft.).To calculate the energy density in your room lighting. Just add the wattage all the different bulbs you have in the room, and remember to divide with efficiency of each type. Incandescent lightbulbs are roughly 5% efficient (the rest is heat), fluorescent lightblub are roughly 95% efficient, and LED lightbulbs are roughly 99.8% efficient. Now you have the total energy. Then divide that by the total boundary surface, just calculate all walls, ceiling, and floor surfaces. Then you get the energy density of your room lighting. In most cases it'll be 100s if not 1000s of times less.Now to finish off. Take the active surface area of the solar cells and multiply the energy density with that and then multiply with the solar cell's efficiency which is typically 14% for crystalline cells and 8% for thin film cells.[/citation]

DAT KNOWLEDGE. +1
 
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