ION Solar Blog

Solar Terms Defined

In our Solar Glossary, we breakdown all of the technical solar terms you need to know.

Solar Terms Defined A-to-T

AC Disconnect – Used to separate the system from the electrical grid (on/off switch for the solar). It is typically mounted on the wall between the inverter and utility meter.

Alternating Current (AC) – An electric current in which the direction of flow is reversed at frequent intervals–usually 100 or 120 times per second.

Alternative Energy – Energy sources that are generated in ways that don’t harm the environment. They do not depend on natural resources such as fossil fuels. ( See Also renewable energy)

Array – Solar PV panels or modules that are interconnected to create one electricity-producing unit.  (See Also solar panel, efficiency, and module)

Azimuth Angle – Azimuth is the arrays’ orientation in terms of degrees.  Just like a compass the directions on an azimuth angle goes as follows: North = 0°, East = 90°, South = 180°, and West = 270°

Balance of System (BOS) -All of the components of a solar system other than the solar panels. This includes wiring, inverters, switches, mounting hardware, monitoring system.

Building Permit Application (BPA) – Application submitted to permitting jurisdiction.

Direct Current (DC) – An electric current in which electrons flow in one direction only.

Disconnect – Switchgear used to connect or disconnect components in a photovoltaic system.  This allows the DC current between the modules to be interrupted before reaching the inverter.

Distributed Energy Resources – Electrical generation performed by a variety of small,  grid-connected systems.

Efficiency – Efficiency is the amount of sunlight captured by a solar panel that gets converted into usable electricity.

Electrical Current – The rate of flow of an electric charge past a point or region. Electric currents are most commonly carried by electrons moving through a wire.

Electrical Grid – An interconnected grid that transmits electricity from providers to consumers.

Energy Audit – An analysis performed to show how much energy is used in a home.

Federal Tax Credit – Homeowners can deduct 30 percent of the system cost from their federal tax liability. This tax credit applies to both residential and commercial systems until the end of 2019. The federal tax credit will drop to 26 percent in 2020, then to 22 percent in 2021.

Fixed Tilt Array – A photovoltaic array set at a fixed angle. (See Also array)

Gigawatt (GW) – A unit of power equal to 1 bill Watts; 1 million kilowatts, or 1,000 megawatts.

Grid-Connected System – A solar system in which the photovoltaic arrays are the central generating powerplant and its energy is connected to the electrical grid or utility grid.

Ground-Mounted Solar – Solar arrays that are installed on the ground rather than on a roof.

Interconnection – Interconnection is the process of connecting your solar system to the electrical utility grid. Before you can connect to the grid, the system owner must obtain written approval from their utility provider. This Permission To Operate authorizes the owner to power on their system. (See Also grid-connected system, electrical grid, and net metering)

Inverters – Devices that convert direct current (DC) electricity to an alternating current (AC) electricity. This conversion to AC electricity is necessary so that it can be used to power your house.

Kilowatt (kW) – A standard measure of electrical power equal to 1,000 watts.

Kilowatt-Hour (kWh) – A measure of electrical energy equal thousand watts acting over a period of 1 hour.

Life – The expected lifetime a solar system is capable of operating at the specified performance level.

Load – The demand for an energy producing system. This required energy consumption is usually expressed in watts in reference to electricity.

Megawatt – A standard measure of electric generating capacity equaling 1,000 kilowatts, or 1 million watts.

Micro-inverter – A device used in photovoltaics that converts direct current (DC) generated by a single solar module to alternating current (AC).

Main Service Panel (MSP) – Main Electrical Panel, project may require an MSP Upgrade.

Module – Another name for a solar panel. (See Also solar panels)

Mounting Hardware – The racking equipment that is used to mount and secure solar panels to the rooftop.

Net Metering – A process in which solar panels are connected to the electrical utility grid. Excess electricity that is produced and not used immediately will be fed into the utility grid. In the evening and night when the solar system is not producing, the electricity you consume will be pulled from the utility grid. This back-and-forth exchange of power is known as net metering.

Orientation – Placement of the panels in regards to cardinal directions, north, south, east, and west. Azimuth is the measure or orientation from the north.  (See Also azimuth)

Peak Sun Hours – An hour in which the intensity of sunlight is 1,000 watts per square meter. It is during these hours that solar panels are operating at the highest level of efficiency. Peak sun hours shift through the seasons. They can also be affected by the climate you are located in.

Permission to Operate (PTO) – Is the approval from the utility company to interconnect the solar system to the electrical grid.

Photovoltaic (PV) –  Photovoltaic is the conversion of light directly into DC electricity. Rooftop solar modules are a photovoltaic technology that converts light into energy using semiconducting materials.

Power Purchase Agreement – With a Purchase Power Agreement, the homeowner doesn’t own the solar system. Instead, they pay each month to use solar power. Either a solar company or a third party owns the system and is responsible for any maintenance and upkeep. When solar is done this way the system cannot contribute to the appraised value of the house.

Renewable Energy – Energy that is generated from sources that naturally renew and replenish themselves. This includes sunlight, wind, rain, tides, waves, and geothermal heat. (See Also alternative energy)

Solar Lease – This payment option works similarly to a PPA.  You pay a fixed monthly amount for the electricity your panels generate. You enter an agreement with a solar leasing company that entitles you to reap the benefits of the clean power generated by the panels. Think of it as renting your solar panel system.

Solar Loan – A loan gives you the option to own a solar system without having to pay upfront costs.  You finance your solar system with a low, fixed monthly rate.

Solar Monitoring – A system that helps keep track of your PV system’s performance. Through monitoring, you can learn more about your energy consumption, generation, and how you can better optimize your energy usage.

Solar Panel – A photovoltaic panel designed to absorb the sun’s rays. Solar power generated from the panel is then used to generate electricity or heat. (See Also photovoltaic, module, array)

String Inverter – A device used in photovoltaics that converts direct current (DC) generated by all modules to alternating current (AC).

Time of Use –  Type of rate that is used by utility companies to incentive customers to consume energy during the days and times when generating electricity is cheapest. What you pay for electricity varies over the course of the day depending on its demand.



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