In stellar terms, tiny. In human terms, huge.

Googling suggests that global energy usage is estimated to be around 15 terawatts.

Using the most efficient multi-junction solar cells available - which can convert 30% of the light hitting them into electricity - we could generate that with about 6.5 million km² of solar panels: that's about 80% of Australia.

Out at Earth's orbit, it'd need to be 68 million km^2: about the area of the Indian Ocean.