The energy that is changing during a phase change is potential energy. During a phase change, the heat added (PE increases) or released (PE decreases) will allow the molecules to move apart or come together. Heat absorbed causes the molecules to move farther apart by overcoming the intermolecular forces of attraction.

Does potential energy increase during freezing?

When ice or any other solid melts, its potential energy increases. Indeed, this is the only increase in energy, since the thermal kinetic energy, or temperature, does not increase while melting. At each phase change of water, whether ice to liquid water or liquid water to water vapor, the potential energy decreases.

Does potential energy increase from solid to liquid?

In order for the molecules to actually separate from each other, more energy must be added. This energy, called heat of fusion or heat of melting, is absorbed by the particles as potential energy as the solid changes to a liquid.