A solar photovoltaic installation generates an average of 20 MW of power
during a 12-hour period of sunlight and no power during 12 hours of night. A Pb-acid battery system is designed to store one day of solar energy for use at night, and during periods of less than full sunlight. What is the mass of the battery system?

Question

Quizplus · Accepted Answer

The Answer is The total energy produced per day is

\left( 20 imes 10 ^ { 6 } \mathrm {~W} ight) imes ( 12 \mathrm {~h} ) imes ( 3600 \mathrm {~s} / \mathrm { h } ) = 8.64 imes 10 ^ { 11 } \mathrm {~J} = 8.64 imes 10 ^ { 5 } \mathrm { MJ }

\mathrm { Pb }

-acid batteries store

0.13 \mathrm { MJ } / \mathrm { kg }

, so the mass required is

\left( 8.64 imes 10 ^ { 5 } \mathrm { MJ } ight) / ( 0.13 \mathrm { MJ } / \mathrm { kg } ) = 6.6 imes 10 ^ { 6 } \mathrm {~kg}

A Solar Photovoltaic Installation Generates an Average of 20 MW