What is a Photovoltaic Cell? (PV Cell or Solar Cell)
The smallest semiconductor element within a PV module to perform the immediate conversion of light into electrical energy (direct current voltage and current). Also called a solar cell.
How Do Photovoltaic Cells Work?
Whether you already have a solar power system or are just starting to do you initial research into the subject, one aspect that many people often gloss over is how exactly solar panels (or more specifically, photovoltaic cells) convert sunlight into electricity. It's easy to understand how water or wind can turn a turbine to create power in hydro and wind power systems, but for all of us that had a solar calculator as a kid, we just take it by faith that a solar panel creates electricity. Entire volumes have been written on the subject and a short article can't go into too much detail, but let's take a quick overview of how our abundant resource of sunlight can become electricity.
The first known observation of what is known as the photoelectric effect was by French physicist, Edmund Bequerel in 1839. This initial discovery that certain types of materials can produce small amounts of current when exposed to light led to the modern usage of photovoltaic cells that are used in today's solar panels.
To construct a solar cell, semiconductor wafers (similar in look and concept to those used to create computer chips) are constructed to form an electric field (positive on one side, negative on the other). As sunlight hits these fields, the electrons are agitated which produces energy, and if the cells are connected to a circuit, this energy can be captured and used or stored in a battery.
Currently, the highest level of efficiency achieved by a solar cell is around 35%. This is achieved by using several different components stacked on top of each other that each react to a different spectrum of solar radiation. Think about it in terms of insulating a house; the exterior walls, the fiberglass insulation, the drywall and the paint all keep different amounts of heat or cool air from passing through. Residential systems typically don't use these more expensive high-efficiency cells, but in the future they will. If 35% efficiency seems low, consider that coal energy is around 28% efficient, and there's the added bonus that you don't have to send someone down into a mine to keep the sunlight flowing.
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