Solar Terms     • Alternating Current (AC) Electricity Electricity characterized by the back-and-forth flow of current, in the US at a frequency of 60 hertz. Electricity is commonly delivered to businesses and residences as alternating current.     • Clean Technology Renewable energy and energy efficiency technologies plus other technologies that make use of resources more environmentally benign and/or reduce carbon emissions.     • Combiner Part of a solar electricity system that brings the electrical currents generated by the system’s solar panels together into a single source of direct current electricity.     • Direct Current (DC) Electricity Electricity characterized by the unidirectional flow of current. This is the type of electricity that is supplied by batteries.     • Inverter Part of a solar electricity system that transforms direct current electricity into alternating current electricity.     • Kilowatt Hour (kWh) A measurement unit for electrical energy.     • Net Metering - An arrangement by which excess solar electricity produced by a customer’s facility is supplied to the electrical utility grid, causing the customer’s electric meter to spin backwards and generate credit to the customer’s electric utility account.     • Power Purchase Agreement (PPA) Long-term agreements between an energy provider and a customer to purchase on-going power at rates with pre-determined annual increases.     • Photovoltaic (PV) Cell The basic component of solar technology that converts solar power directly into electricity. Literally, photovoltaic means “light-generated voltage.”     • Renewable Electricity Renewable electricity is electricity generated without use of fossil fuels.     • Solar Array A grouping of multiple solar panels.     • Solar Module A grouping of photovoltaic cells into the building block for solar panels.     • Solar Panel A grouping of solar modules that become the main element in a solar electricity system. Solar panels are installed on rooftops or other open spaces that get full sunlight.     • Solar Power Generation Solar power generation is electricity produced from the sun unlike typical electricity which uses fossil fuels. Fossil fuels are non-renewable electricity sources, meaning that as they are used, the Earth's supply depletes. Solar power generation is a process that harnesses the energy received from the sun and channels it into existing electrical grids.