Energy Consumed is expressed in kiloWatt hour (kWh) or what we commonly call as unit Energy = Power × Time (for getting Energy in "kiloWatt hour or unit", make Power in kilo Watts and Time in Hours). So Here, Power = 200 Watts or 0.2 kilo Watts Time = 5 Hours/day So Energy consumed in 7 days (in kWh or Unit) = 0.2 kW × 5 hour × 7 days = 7 kWh or 7 units