It's almost incredible that a AA battery can do that much work, but I checked the math: Alkaline AA Battery =~ 3 Wh =~ 10000 Nm Gravitational Potential Ene

It's almost incredible that a AA battery can do that much work, but I checked the math: Alkaline AA Battery =~ 3 Wh =~ 10000 Nm Gravitational Potential Energy =~ kg * m * 10 N/kg 100 kg * 10 m * 10 N/kg == 10000 Nm == AA Battery It also puts into perspective how much solar energy is available. A single 200 W panel (~5 sq ft or ~.5 m^2) can charge hundreds of AA batteries per day, and thus would require lifting more than 10000 kg by 10 m to store a single day's output from just that one panel!