At the distance from the Earth to the Sun, 150 kilometers, solar output is about 1 kilowatt per square meter (500 watts infra-red, 500 watts visible light and 2 watts UV light). http://en.wikipedia.org/wiki/Sunlight
If we were to scale that back up to the surface of the Sun and assuming a theoretical spherical distribution, that would be 4x as much energy per square meter for distance halved, so by the time you get to the surface of the sun, the energy is around 256 KiloWatts/square meter (assuming surface radius of 500,000 kilometers). If you were to scale that down to the centre of the sun, then that's 148 MegaWatts per square meter.
According to the wikipedia entry, the Sun generates 384.6 yotta watts (3.846×10^26 W) per second. 3.846 x 10^20 GigaWatts/second.