With an AM signal modulated 100%, two-thirds of the power is in the carrier, and one third in the sidebands. A 1000 watt carrier has 500 watts p.e.p. in the sidebands at 100% modulation. The carrier and sidebands make up two separate sets of signals, transmitted on or about the same frequency. 1000 watts carrier + 500 watts sidebands = 1500 watts total.