sentence: Cells require protection from the environment and are usually packaged tightly behind a glass sheet.
sentences_before: Solar cells can be used to power tools or to recharge a battery. The first actual request of photovoltaics was to power orbiting satellites and other spacecrafts, but today the most photovoltaic modules are used for grid connected power creation. In this case a tool called an inverter is required to convert the direct current to alternating current.
sentences_after: When more power is required than a single cell can give off, cells are electrically connected together to form photovoltaic modules, or solar panels. A single module is enough to power an emergency telephone, but for a house or a power plant the modules must be arranged in multiples as arrays.
concept_name: cell
headings: Photovoltaics Solar Cells
categories: Solar energy Solar power