The term solar panel is used colloquially for a photo-voltaic (PV) module.
A PV module is an assembly of photo-voltaic cells mounted in a framework for installation. Photo-voltaic cells use sunlight as a source of energy and generate direct current electricity. A collection of PV modules is called a PV Panel, and a system of Panels is an Array. Arrays of a photovoltaic system supply solar electricity to electrical equipment.
The most common application of solar energy collection outside agriculture is solar water heating systems.