A petawatt-hour (PWh) is a unit of energy equivalent to one quadrillion watt-hours. It measures the total amount of energy consumed or produced over time, where one watt-hour is the energy used by a one-watt device running for one hour. This large unit is often used in discussions about energy generation and consumption on a national or global scale. To put it in perspective, 1 PWh is enough energy to power approximately 33 billion 30-watt light bulbs for one hour. This measurement is significant in fields like renewable energy, where large-scale production and consumption of energy are analyzed, helping to understand the impact of energy sources like solar and wind.