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Renewable Energy Glossary

  • Alternative Energy

    Energy that does not come from traditional sources, i.e., fossil fuels (coal, oil, and natural gas) or create greenhouse gasses. Renewable energy sources, like solar, wind, and tidal energy, are considered alternative energy.

  • PV Array (Photovoltaic Array) – Solar Array

    A group of Photovoltaic (PV) or solar modules and panels arranged in a particular configuration based on location and need. Generally, a complete unit needed to generate power.

  • Balance of System (BoS)

    The additional equipment made up of wires and electrical hardware to assist in the conditioning, transmission, and storage of electricity. This does not include the solar panels, but rather the equipment needed for the next steps once the energy has been created and stored.

  • Battery Energy Storage System (BESS)

    A system of devices used to collect and stockpile renewable energy from an energy grid until it is needed and then released to power customers’ homes or businesses. A BESS ensures that customers can power their homes and businesses on days when there is limited sunlight or wind.

  • Community Solar

    A central and shared solar power project for a set geographical area that sends generated electricity to multiple locations (individuals, businesses, and other groups).

  • Distributed Energy Resources (DER)

    A small-scale power generator that is used at the local level. The energy produced is used close to the source. They are used for production and storage of renewable power and for power reserves to be used at a later time. Examples include solar panels and electric cars.

  • EPC Services

    EPC stands for Engineering, Procurement, and Construction. This type of service allows all power-related challenges including: consultation, design, procurement of equipment, project management, installation, and post-installation support – to be completed in-house without outsourcing or subcontractors.

  • ESG (Environmental, social, and governance)

    ESG is a set of standards for a company’s behavior used by socially conscious investors to screen potential investments. Environmental focuses on how a company safeguards the environment (for example, corporate policies addressing climate change). Social criteria assess how it manages relationships with employees, suppliers, customers, and the communities where it operates. Governance judges a company’s leadership, executive pay, audits, internal controls, and shareholder rights.

  • Federal Investment Tax Credit (ITC)

    A federal income tax policy put in place to assist in the growth of solar energy in the United States both commercial and residential markets. It is a tax credit that homeowners can claim off of the total cost of their solar system equipment and installation. The credit can then be applied as a reduction in the amount owed in federal taxes. For commercial use, it can be claimed by the business that installs, develops, or finances the operation.

  • Electrical Grid

    A system used to connect power providers with consumers from start (power generation at a plant) to finish (consumer homes and businesses) using a series of transmission lines to service a large area.

  • Grid-Connected System

    A solar system installed at a home or business that is connected to the larger electric grid. This allows customers to power their homes or businesses with energy produced from their solar system and put any excess energy back into the grid. When energy cannot be produced, the customer has access to the larger grid to receive power.

  • Grid Parity

    Grid parity is when the use of alternative energy (mostly solar or wind) costs less than or equal to the cost of using power from a traditional source like coal, oil, or natural gas.

  • Ground-mounted Solar

    A free-standing system of solar panels that can be implemented on land in a large open area.

  • High Voltage Disconnect

    A switch used to completely turn off an electrical circuit for service or maintenance. This switch is most often found in electrical distribution and machinery where the main power source must be disabled before repair.

  • Interconnection Agreement

    A written notice to a utility company from a homeowner alerting them of plans to activate a solar system installation that will connect to the electric grid. The agreement allows the homeowner to use the power from the power lines when their solar system is not creating enough power. This agreement also enables customers to partake in net metering because the power generated from the solar system can be put back into the grid.

  • Inverter/Micro Inverter

    An inverter is a device used to change the electrical current from direct current (DC) to alternating current (AC). It is powered by the direct current source but does not create any power on its own.

    Micro inverters are typically used with solar panels to convert the direct current absorbed by the panel into the alternating current or electricity for a consumer’s home or business.

  • Watt (W) vs Watt-Hour (Wh)

    Watt (W): Unit of measurement for the rates of power at a moment in time. It quantifies the rate of energy conversion from one form to another. A Watt represents the amount of energy (measured in joules) that an electrical unit is burning per second.

    Watt-Hour (Wh): Unit of energy equal to 1 watt of power used over an hour. This is not a standard unit of measurement but is used in relation to electrical components.

    Kilowatt (kW): Unit of energy equal to 1000 watts. Used in regards to the output of power in an engine, motor, tools, and machinery.

    Megawatt (MW): Unit of energy equal to 1 million watts. Typically used when discussing the power from a server farm, data center, large electric motors, and commercial buildings.

    Gigawatt (GW): Unit of energy equal to 1 billion watts. Used when discussing large power plants and power grids.

  • Lead Acid Battery

    A type of rechargeable battery that is low in cost and has a long lifetime. They store energy through a chemical reaction of the lead, sulfuric acid, and water found in the chemical make-up. This type of battery is commonly used in solar systems.

    Battery Chemistry: A battery is used to store chemical energy and then convert it to electrical energy. To produce electricity a flow of electrons is need within the battery. There are many different type of metals and chemical compounds that can be used in different ratios and this formula is known as the battery chemistry.

    Valve Regulated Lead Acid Batteries (VRLAB): A battery that must be stored in an object vertically due to the corrosive nature of the liquid sulfuric acid solution inside it that will mist when charging and discharging. This type of battery tends to be stable and offer a long shelf life which is why it can often be found in an uninterruptible power supply as a backup for a power outage.

    Gelled Electrolyte Lead Acid Battery (GEL): A more modern VRLA battery where a fumed silica is mixed with the sulfuric acid solution to create a solidified electrolyte so the battery doesn’t have to be vertical like the VRLA battery. It is less likely there will be a spill or evaporation with this type of battery.

    Advanced Glass Mat: A battery that holds the electrolytes in a mat made of thin glass fibers that absorb the acid. These batteries are safer as well as more efficient and durable. Less acid is used so that they last longer.

  • Net Metering

    A billing system that utility companies use for homeowners that have and use solar systems and connect to the power grid. The homeowner can use energy from the power grid when energy from their solar system is not being produced, and excess energy produced that is not used is put back into the power grid.

  • Operations and Maintenance (O&M)

    The plans and procedures in place for daily duties and services required to ensure a building and/or structure is performing as designed and constructed. This plan includes training, cleaning, and other duties, as well as information about the property and equipment upkeep.

  • Solar Irradiance (and Peak Sun Hours)

    The measure of the amount of light energy (wavelengths) from the sun hitting a square meter of another object on Earth. Solar Irradiance can vary over time and location because the sun’s wavelengths are absorbed in different parts of the atmosphere at different capacities.

    The peak sun hour is when the solar irradiance is measured at 1000 Watts per square meter. The peak hour is at midday when there is the most sunlight. This metric is used to compare sunlight and energy production opportunities in different locations.

  • Module

    A single group of connected solar cells that are grouped together to create a larger solar panel.

  • Peak Demand/Load

    The point when the demand for power and electricity is at its highest. This is usually measured over 15-30 minute periods and then averaged by the hour, day, season, or year to compare how much power is being used vs. how much power is being generated.

  • Performance-based Incentive

    A payment (or credit) based on the amount of energy produced by a solar system (measured per kilowatt/hour).

  • Power Density

    Measurement of power output and energy system conversions. A high power density means there is a large internal capacity to output a large amount of energy in a short amount of time. A low power density means there is a lower amount at a slower rate or that extra time will be required between outputs.

  • Power Purchase Agreement (PPA)

    A financial agreement for a third-party developer to install, own, and operate a solar energy system on a customer’s property. The developer sells that power to the customer at a fixed rate for a set amount of time.

  • Commercial Property-Assessed Clean Energy (CPACE)

    A financing plan for commercial building owners to borrow money to enhance energy efficiency and renewable energy efforts. The repayment plan is determined by an assessment of the property tax bill.

  • Rate of Production

    The ratio of how much energy is produced to the amount of time required to produce it.

  • Renewable Energy

    Energy sources that are naturally replenished over time and will never run out. They produce less greenhouse gas emissions than fossil fuels that can’t be renewed. Examples include solar, wind, and hydropower.

  • Solar Canopies

    Elevated structures that expand over paved areas (i.e., parking lots) that have overhead solar panels that provide shade below them. This provides power generation on top and convenient and protected covered parking below for vehicles.

  • Solar Cell

    A device used to generate then convert power from the sun into electricity through reflection and absorption. Multiple cells will create a module, and multiple modules will create a panel.

  • Solar Lease

    A contract with a solar company that allows customers to pay a fixed monthly rate for the use of a solar installation. While the customer does not own the solar installation, they do not pay any upfront costs or maintenance expenses.

  • Uninterruptible Power Supply (UPS)

    A backup system to power electrical equipment in case of a power disruption, a drop in voltage, or a power failure.

  • Volt/Voltage

    Volt is a unit of measure for voltage. Voltage is the difference in electrical potential between two points. It is a pressure that pushes electrical current through a circuit (loop). That pressure can be caused by a build-up of an electrical force’s charge.

  • Energy/Power

    Energy is the capacity to do work. Power is the rate at which energy is used.

  • Solar Renewable Energy Credits (SREC)

    A performance-based solar incentive where certificates can be sold to utilities. An SREC represents one megawatt hour of solar energy.