Solar energy is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, and more. It is a very important source of renewable energy and its technologies are broadly characterized as either passive solar or active solar depending on how they capture and distribute solar energy or convert it into solar power.
Solar panels are devices that convert light into electricity.Solar panels are a collection
of solar cells. Multiple solar cells spread over a large area work together to make enough power.
The more light hits the solar cell the more power is produced which is why it is the go-to way to provide spacecraft with electricity. 
Solar panels generate electricity from an effect that is called the photovoltaic
effect which is a process that generates an electric current in a photovoltaic cell when it is exposed to sunlight. These solar cells are composed of two different types of semiconductors a p-type and an n-type—that are joined together to create a p-n junction.
By joining these two types of semiconductors, an electric field is formed in the region
of the junction as electrons move to the positive p-side and holes move to the negative n-side.
This field causes negatively charged particles to move in one direction and positively charged
particles in the other direction.
Light is composed of photons, which are simply small bundles of electromagnetic radiation or energy. When light of a suitable wavelength is incident on these cells,
energy from the photon is transferred to an electron of the semiconducting material,
causing it to jump to a higher energy state known as the conduction band.
In their excited state in the conduction band, these electrons are free to move through the material,
and it is this motion of the electron that creates an electric current in the cell.