In $1.0\,\text{s}$, the energy received per unit area by a set of solar panels is $120\,\text{J m}^{-2}$. During $1.0\,\text{s}$, the set of solar panels changes $720\,\text{J}$ of light energy into $120\,\text{J}$ of useful electrical energy. What is the total surface area of the panels, and what is the efficiency of the system?