You need to make sure that they are outside, and basically can see the sky, either on a roof or through glass. You also need to have an energy regulator placed next to the solar generator, and then next to the regulator, the machine(s) you wish to power. You energy regulator can be found int he /sf guide under 'energy and electricity' and any machines you wish to pwer can also be founnd in the 'energy and electricity' section of the guide.