How many watt does a Solar cell output?

Solar cells are available in sizes (power outputs) ranging from a few milliwatts to kilowatts and more. It's all about size (the area and number of the cells) and a few other factors. Arrays of solar cells that some call solar panels will deliver energy in a range dependent on the wiring and size of the array, the attitude of the mount, and the geographic location and weather in the area in which it is erected. Just think it through and it will become apparent. Probably the most critical factor as regards the power output of the unit or assembly is termed the maximum power point. Power out is determined by current times volts. At some "happy medium" between maximum current and maximum voltage (neither of which is the "best" point of operation) is that magic combination of volts and amps that result in the solar cell delivering maximum power ( with other factors optimized, of course). It's the electronics support circuitry that controls the point of best operation. Start reading and come up to speed on this amazing principal of power generation. Begin with the link provided.

One thing to note is that efficiency of a panel is also taken into consideration are you using a Serengeti with a 13% solar cell efficiency or SPR 225 with an 18%. The efficiency effects the amount a solar cell will output.