The difference is that the satellites' 230 W/m^2 is in a very narrow frequency band, and can thus be harvested and converted efficiently, where solar radiation

The difference is that the satellites' 230 W/m^2 is in a very narrow frequency band, and can thus be harvested and converted efficiently, where solar radiation is mainly at much higher frequencies, and, more importantly, spread out over a wide spectrum of frequencies. Our current best methods for converting these high-frecuency photons (solid state solar cells) only work well around a specific design frequency, and so they can convert only a limited part of the solar spectrum.