Question: how much power is 12 volts?
Answer: The 12 volt system you have is rated at 0.2 amps at 12 volts. Multiply the amps by the hours and you get the result of 1.2 amp-hours per day. You use three 20 watt 12 volt lights for about four hours each night. The power consumption for each light we worked out earlier to be 1.67 amps.