Use this handy glossary to better understand some of the technical terms that relate to solar power and other renewable energy sources.

  • 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.
  • Renewable Portfolio Standard (RPS) is a regulation that requires the increased production of energy from renewable energy sources, such as wind, solar, biomass, and geothermal. Other common names for the same concept are Renewable Electricity Standard (RES) at the United States federal level and Renewables Obligation in the UK. The RPS mechanism generally places an obligation on electric companies to produce a specified fraction of their electricity from renewable energy sources. Certified renewable energy generators earn certificates for every unit of electricity they produce and can sell these along with their electricity to supply companies. Supply companies then pass the certificates to some form of regulatory body to demonstrate their compliance with their regulatory obligations. Because it is a market mandate, the RPS relies almost entirely on the private market for its implementation. Unlike feed-in-tariffs which guarantee purchase of all renewable energy regardless of cost, RPS programs tend to allow more price competition between different types of renewable energy, but can be limited in competition through eligibility and multipliers for RPS programs. Those supporting the adoption of RPS mechanisms claim that market implementation will result in competition, efficiency and innovation that will deliver renewable energy at the lowest possible cost, allowing renewable energy to compete with cheaper fossil fuels energy sources.
  • Solar Alternative Compliance Payment The Solar Alternative Compliance Payment (SACP) is the amount that Load Serving Entities (LSEs), i.e. electricity suppliers, must pay per MWh of solar electricity that they are unable to generate themselves or buy rights to through SREC purchases in order to meet the state Renewable Portfolio Standard (RPS) solar requirement.
  • 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.
  • Solar Renewable Energy Credit (SREC) a form of Renewable Energy Certificate or Green tag. SRECs exist in states that have Renewable Portfolio Standard (RPS) legislation with specific requirements for solar energy, usually referred to as a "solar carve-out". SRECs represent the environmental attributes from a solar facility, and are produced each time a solar system produces one megawatt-hour (MWh) of production. The additional income received from selling SRECs increases the economic value of a solar investment and assists with the financability of solar technology. In conjunction with state and federal incentives, solar system owners can recover their investment in solar by selling their SRECs through spot market sales or long-term sales.