History and Development
– Solar panels were first observed to create an electrical charge from light exposure in 1839 by Edmond Becquerel.
– In 1873, Willoughby Smith discovered that light hitting selenium could cause a charge, replicating Becquerel’s observation.
– Charles Fritts created the first commercial solar panels in 1881, although they were inefficient compared to coal-fired power plants.
– Russell Ohl designed the solar cell used in modern solar panels in 1939 and patented it in 1941.
– Bell Labs used Ohl’s design to create the first commercially viable silicon solar cell in 1954.
– The production of crystalline silicon panels has increased steadily over the years.
– Crystalline silicon accounted for 95% of worldwide PV production in 2021.
– Thin-film technologies make up the rest of the overall solar panel market.
– Emerging third-generation solar technologies utilize advanced thin-film cells for higher efficiency at a lower cost.
– High-cost, high-efficiency multi-junction (MJ) cells are used in solar panels on spacecraft.
Theory and Construction
– Photovoltaic modules consist of solar cells that use light energy from the sun to generate electricity through the photovoltaic effect.
– Most modules use crystalline silicon cells or thin-film cells.
– Cells must be protected from damage and moisture.
– Modules can be rigid or semi-flexible.
– The power of a module is determined by the amount of light and the electrical load connected to it.
Cell Connection Techniques
– Solar cells in modules are connected together using various techniques.
– Passivated emitter rear contact (PERC) adds a polymer film to capture light.
– Tunnel oxide passivated contact (TOPCon) adds an oxidation layer to the PERC film to capture more light.
– Interdigitated back contact (IBC) is another technique used for cell connection.
Arrays of PV Modules
– A single solar module produces limited power, so installations usually contain multiple modules.
– A photovoltaic system includes modules, an inverter, a battery pack for energy storage, and other components.
– Equipment is selected to optimize output, reduce power loss, and convert from DC to AC.
– Interconnection wiring, circuit breakers, fuses, disconnect switches, and voltage meters are also part of the system.
– Optional solar tracking mechanisms can be used.
Smart Solar Modules
– Smart modules have embedded power electronics that offer enhanced functionality.
– Power electronics such as maximum power point tracking (MPPT) power optimizers are used to maximize power harvest.
– Solar performance monitors are incorporated for data and fault detection.
– Power electronics attached to the frame or connected through a connector are not considered smart modules.
– Several companies have started incorporating embedded power electronics into each PV module.