LEDs produce roughly four times as much plant usable light per watt as compared to traditional grow lights. Many LED suppliers argue that a 200 watt LED is equal to 800 watts of traditional grow light power. However, a more realistic rule-of-thumb ratio of 1:2.
A better way to gauge power level is by looking at the surface area adequately covered by the light. The SolarSystem 1100 which consumes 800 watts is designed to cover a 5' x 5' grow area in flower, similar to a 1000 watt HPS light. In the same respect, a SolarSystem 550 replaces a 600w HPS with only 400 watts maximum. Please see product pages for more information.