A city in a warm part of this country, such as California, Arizona or Nevada, or cities in southern parts of European and Asian countries, can enjoy utility scale solar energy to bring clean and reliable electricity to houses and buildings. Solar energy has been around for centuries, and in recent decades it has advanced to the point where it is now possible to produce commercial solar power on a scale large enough to power cities and towns in warm-weather areas. The process is fascinating, and it all begins with photovoltaic solar cells.

Photovoltaic cells utilize a semiconductor, which captures the energy contained in sunlight. The most common semiconductor material used for solar cells is silicon. At the moment that the silicon semiconductor absorbs some of the sun's light, the energy is released into the semiconductor as electrons.

The electrons are free and bouncing around, and so in order to make them usable for energy an electrical field gets the electrons going in the same direction, a process that creates electrical current that we can use to power the appliances and lights around our homes. The energy is accessed from the cell from metal contacts at the top and bottom of the cells, in a similar fashion to a traditional battery that you would use in a flashlight.

For utility energy to come from a solar array, the photovoltaic solar cells, which are rather small on their own, must be combined. The linked cells, called concentrated photovoltaic technologies, can utilize a multijunction system to connect the cells, thereby significantly increasing their energy output.

Energy efficiency for commercial solar power has also improved in a variety of ways. Large solar systems may utilize Fresnel lenses, which are used in theatre lighting systems and video projectors, in order to focus large quantities of sunlight onto the concentrated photovoltaic cells, in order to increase their energy output efficiently.

Knowing where the sun is in the sky and its relationship to the photovoltaic system is also important in this regard. Utility energy technologies can add components that help to track the position of the sun relative to the photovoltaic solar array, so that the array is always in the best position for soaking up the sun's rays, thereby increasing the system's efficiency.

Advances have occurred in solar technologies such that even commercial solar power can be scaled to meet the needs of a single company or increased to fuel an entire city.