Wattage (the amount of electric power) is calculated by multiplying a solar panel’s voltage by the amps of current it produces. Each solar cell will produce a voltage of about 0.5 volts, whether it’s big or small. By attaching single cells together in a series, you can create a higher voltage. Amps, on the other hand, do vary based on size, so the bigger the cell, the more amps you’ll get. Connecting cells in parallel also creates more amps of current.