Solar panels, also known as photovoltaic modules, are devices designed to capture sunlight and convert it directly into usable electrical energy. This conversion process is based on the photovoltaic effect, a physical and chemical phenomenon first observed in the 19th century. At the heart of every solar panel are numerous photovoltaic cells, typically made from semiconductor materials like silicon. These cells are the fundamental units responsible for generating electricity. When photons, which are particles of sunlight, strike the surface of a PV cell, they can transfer their energy to electrons within the semiconductor material. This energy boost allows the electrons to break free from their atomic bonds, creating electron-hole pairs. The internal structure of the cell, engineered with a positive and a negative layer, creates an electric field. This field forces the freed electrons to move in a specific direction, generating a flow of direct current electricity.

The majority of solar panels installed today are built using crystalline silicon technology. There are two primary types: monocrystalline and polycrystalline. Monocrystalline solar panels are made from single-crystal silicon, giving them a uniform dark appearance and generally offering higher efficiency rates in converting sunlight to electricity. Polycrystalline solar panels are constructed from silicon fragments melted together, resulting in a blue speckled look and often a slightly lower efficiency, though frequently at a lower cost. The individual silicon cells are interconnected and sealed between a durable glass front sheet and a protective polymer backsheet. This laminate is then framed with aluminum for structural rigidity and ease of mounting. This entire assembly protects the delicate cells from weather while allowing maximum light penetration.

The direct current produced by a solar panel is not immediately compatible with most home appliances and the electrical grid, which operate on alternating current. Therefore, a critical component of any solar energy system is the inverter. The inverter's role is to convert the DC output from the solar panels into usable AC electricity. For residential systems, a single string inverter might handle the output from multiple panels wired together. Alternatively, microinverters or DC optimizers can be attached to each individual solar panel, allowing for independent operation and mitigating power loss if one panel is shaded. The electricity generated can then be used on-site, fed into the public grid, or stored in batteries for later use. The efficiency of a given solar panel, a percentage indicating how much sunlight it converts to electricity, is influenced by cell technology, temperature, and the intensity and angle of incoming sunlight. Understanding this basic science and construction clarifies how these silent arrays on rooftops and in fields harness the sun's abundant energy to generate clean power.