Basic Terminology
The basic and very important formula you need to know to make sense of solar cells is this:
Power (P) = Current (I) Multiply by Voltage (V), or P=I*V
Power's unit of measure is watt,
Current's unit of measure is amp,
Voltage's unit of measure is volt.
So in our solar cell's specific example, if each solar cell is rated at 1.75 watts on average, and the voltage is 0.5, you do a little algebraic math, then to get the amps (I), since P=I*V, so I = P / V , therefore I (amps) = 1.75 watts divided by 0.5 volts = 3.5 amps.
It's important to understand the concepts of series connection and parallel connection when stringing these solar cells together to make a solar panel.
1) Series connection of the cells increases voltage but not amperage; parallel connection of the cells increases amperage but not voltage. Series connection is when you connect the positive terminal of a cell with the negative terminal of the next cell.
2)Parallel connection is when you connect the positive terminals of all cells in the set of cells with a tabbing wire and all the negative terminals of all cell in the same set. You can use a combination of series and parallel connections to get the right voltage and amperage for your solar panel.
The cell specifications above were given to us by the manufacturer as averages. Variations are possible. To make a 18 volts panel, for example, you connect 36 cells in series (36 cells times 0.5 volt each = 18 volts). And 36 * 1.75 (each cell in theory averages 1.75 watt) watt = 63 watts. The amps you will be getting is 63 watts divided by 18 volts = 3.5 amps.
Below is a useful link to basic solar electrical terminology:
http://www.solar4power.com/solar-power-glossary.html
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