A Glossary of Comon Solar Energy Terms

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Helpful Solar Terms And Definitions

We've put together a helpful glossary of solar energy terms to save you the time of having to search Google. This glossary is frequently updated to reflect changes in the residential solar industry. If you have any suggestions feel free to get in touch. The more informative this glossary becomes, the more helpful it will be for other homeowners.


Alternative Energy - The first term in the solar panel vocabulary words is alternative energy. The term is used to stand for the energy that comes from sources that bring minimal or no harmful causes to the environment. The sources for this kind of energy are usually natural and renewable.

Annual Solar Savings - The annual solar savings of a solar building is the energy savings attributable to a solar feature relative to the energy requirements of a non-solar building.

Annual True-Up Statement - After 12 months, your monthly net energy charges and credits are reconciled in an annual True-Up statement. Any remaining charges must be paid and any excess surpluses are typically reset to zero.

​Array -  See photovoltaic (PV) array.

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Balance of System (BOS) - A solar system is made up of much more than solar panels. The term BOS (balance of system) stands for all the other components of a solar system besides the panels.

Battery Backup -  A solar battery backup is a battery that stores energy from a solar PV system. The system's panels absorb energy from the sun and convert it to electricity which then passes through the inverter for your home to use. Also see solar battery storage

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California Solar Consumer Protection Guide - The California Public Utilities Commission (CPUC) presents the California Solar Consumer Protection Guide. This guide provides important information to homeowners thinking of going solar. The CPUC recommends that solar providers give out this guide during their first contact with potential customers.


Charge Controller -  If you have a battery backup, a charge controller regulates the electricity going into the battery, and protects the battery charge during off hours. A charge controller is needed because a battery can be damaged by a fluctuating charge, which would happen if the battery were connected directly to the solar panel system

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Days of Storage -  The number of consecutive days a solar system will meet a defined load without solar energy input from the sun. 


Direct Current (DC) -  A type of electricity transmission and distribution by which electricity flows in one direction through the conductor, usually relatively low voltage and high current. To be used for typical 120 volt or 220 volt household appliances, DC must be converted to alternating current, its opposite.

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Electric Bill -  The bill that a local utility issues to a homeowner for the electricity that their home consumes.

Electrical Grid - An integrated system of electricity distribution, usually covering a large area


Electrical Panel Upgrade -  Electrical panels divide incoming electrical power from the grid into subsidiary circuits to distribute power throughout the building. With a 25-40 year lifespan and an ever-growing reliability on electricity, these panels need upgrading and replacement.

Energy Audit - An energy audit is a process in which the homeowner assesses the amount of power that their home or business requires or uses. The process can also incorporate various ways they can use to make their buildings more energy-efficient.

Energy Storage - When a battery stores power from a PV (photovoltaic) solar system.


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Federal Solar Tax Credit -  Commonly referred to as the investment tax credit (ITC), the federal solar tax credit gives homeowners a dollar-for-dollar reduction against their federal income tax. It is regarded as the most significant financial incentive for solar in the U.S.

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Gigawatt -  A unit of electrical power equal to one billion watts or 1000 megawatts

Greenhouse Gases - Gases that trap heat in the atmosphere increasing the rate of climate change


Grid-Tied Solar SystemGrid-tied systems are solar power setups that are connected to the electricity grid — and work without any battery backup equipment. They are currently the most common type of solar panel system in American homes


Ground-Mounted Solar - Ground-mounted solar is an array of solar panels which are installed on the ground or land. 


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Hybrid Solar System -  Hybrid solar systems generate power in the same way as a common grid-tie solar panel system but use special hybrid inverters and batteries to store energy for later use. This ability to store energy enables most hybrid systems to also operate as a backup power supply during a blackout.

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Interconnection Agreement - Received at some point during the process of going solar, this is the contract entered into, between the local utility company and the homeowner. The contract is meant to allow the homeowner to access the power grid by linking it to their solar system.

Installer - Installers are sent by solar providers to your home to check roof, ground, and electric conditions and to install the solar system. They must be licensed like a solar provider


Inverter -  A solar inverter or PV inverter, is a type of electrical converter which converts the variable direct current output of a photovoltaic solar panel into a utility frequency alternating current that can be fed into a commercial electrical grid or used by a local, off-grid electrical network.


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Joule - A metric unit of energy or work; 1 joule per second equals 1 watt or 0.737 foot-pounds; 1 Btu equals 1,055 joules.


Junction Box - The solar panel junction box is an enclosure placed at the underside of the solar PV module (solar backsheet). It is an important part through which two or more solar PV panels are interconnected

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Kilowatt (kW) -   A standard unit of electrical power equal to 1000 watts, or to the energy consumption at a rate of 1000 joules per second.

Kilowatt-hour (kWh) -   1,000 thousand watts acting over a period of 1 hour. The kWh is a unit of energy. 1 kWh=3600 kJ.

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Life-cycle cost - The estimated cost of owning and operating a photovoltaic system for the period of its useful life.

Local Utility - Where homeowners buy grid electricity and where power is generated at a local level

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Megawatt (MW) - 1,000 kilowatts, or 1 million watts; standard measure of electric power plant generating capacity.

Megawatt-hour (MWh) - 1,000 kilowatt-hours or 1 million watt-hours.

Meter - A meter is what monitors the energy production of your home solar system. You’re probably familiar with the traditional meter, but if you get solar panels, you’ll need a bi-directional or digital meter.

Micro-inverter - While an inverter converts the DC power of several solar panels into AC, a micro-inverter converts the DC power from a single panel. 

Mounting System - is the foundation that holds your solar array in place. Mounts are used to attach solar panels to the roof, ground, or another surface on your property. With proper installation, a sturdy mount secures your panels in harsh weather and protects your investment.


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Net Energy Metering - A practice in which the utility company will credit you for the excess electricity generated by your solar panels. You can then draw upon these credits when your installed solar panels do not produce enough electricity to match your use; most commonly in the night when the sun is not shining. When excess electricity is produced by your solar system, it is sent back to the grid and the electric company must buy that energy from you.​

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O&M (Operations And Maintenance) - These are the continuing operational requirements of a solar power system. They may include repairs, cleaning, bill management, and replacement of parts, among others. Principally, the term is used in the utility-scale and larger-scale commercial solar systems.

Off-grid - The power grid refers to the network that delivers electricity to your home An off-grid system is designed to help people function without the support of this network.

Offset - Your solar offset is the amount of electricity your solar system produced in a year divided by the total amount of electricity your home actually used that year expressed as a percentage. Solar production measures the amount of electricity your solar system actually produces.

Overproduction - The energy that is generated above the committed level in a customer's agreement


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Panel - See photovoltaic (PV) panel.

Peak Sun Hours - The peak hours refer to the quality of the sunlight the solar panels absorb, rather than the length of time the panels are exposed to daylight. They are the hours of the day, which the sunlight intensity is 1,000 watts for every square meter.

Photovoltaic (PV) - Photovoltaic (PV) is a technology that helps to convert sunlight light into electrical power using semiconducting materials that absorb electrons from the sun. A photovoltaic system makes use of solar panels to generate solar power.

Photovoltaic (PV) array - An interconnected system of PV modules that function as a single electricity-producing unit. The modules are assembled as a discrete structure, with common support or mounting. In smaller systems, an array can consist of a single module.

Photovoltaic (PV) cell - The smallest semiconductor element within a PV module to perform the immediate conversion of light into electrical energy (direct current voltage and current). Also called a solar cell.

Photovoltaic (PV) system - A complete set of components for converting sunlight into electricity by the photovoltaic process, including the array and balance of system components.

Polycrystalline - PolyCrystalline or MultiCrystalline solar panels are solar panels that consist of several crystals of silicon in a single PV cell. Several fragments of silicon are melted together to form the wafers of polycrystalline solar panels. ... These solar panels absorb energy from the sun and convert it into electricity. Also see multicrtalline

Power Purchase Agreement (PPA) - This is a type of solar-purchasing contract. A developer finances a solar energy system and installs it on a customer’s property—usually at little to no cost for the customer. The energy produced is then sold to the customer at a set cost that is cheaper than traditional utility rates. When the agreement ends, the customer often has the option to extended the term, remove the equipment, or purchase the array from the developer at a reduced cost. For more information on PPAs, check out our Solar Financing Options post.

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Quad - Unit of heat equal to one quadrillion Btu. One quadrillion Btu (1,000,000,000,000,000 Btu).

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Rated Battery Capacity - The term used by solar battery manufacturers to indicate the maximum amount of energy that can be withdrawn from a battery under specified discharge rate and temperature. 


Renewable Energy - When we talk about renewable energy, it refers to the kind of energy that comes from sources that occur naturally, and that renew themselves continually. These renewable sources of energy include wind, sun, tidal, and geothermal heat.


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Service Transfer - If you sell your home, a service transfer refers to the process of transferring your solar system service to the new owner. The new home owner will be able to take advantage of solar incentives like net metering, more predictable electric bills, and clean, renewable energy for their family.

Solar Array - Combining several solar panels creates a solar array, which is part of a solar system. The typical residential solar array consists of 20–25 solar panels to cover 100% of its energy consumption.

Solar Batterie/Storage - A high-capacity recharegable battery that reserves energy for later consumption that the solar panels produce. The stored electricity ensure that you continue to enjoy power even after nightfall or when sunlight is unavailable.


Solar Canopies - When you install solar arrays that tower above the ground, they form structures that leave the underneath land usable. They create shades that can act as car parks, among other purposes. These shades are what we refer to as solar canopies.


Solar Cell - This is a solar terminology that stands for a single unit that captures light in a photovoltaic solar panel. They are the devices that capture and convert sunlight into electricity through a photovoltaic effect. The process is both a chemical and physical phenomenon. The cells usually consist of silicon semiconductors with a positive and negative layer which creates an electric field.


Solar Efficiency - In solar energy, the term efficiency means the percentage of sunlight that the panels convert into electricity out of the amount of sunlight they receive. The efficiency of most solar panels in the current market ranges from 15% to 24%.​ 


Solar Farm - A solar farm is often referred to as a solar ranch, solar field, or solar park. Spanning between an acre and 100 acres of solar panels, a solar farm allows a community to reap the benefits of a solar electricity system without purchasing, installing, or maintaining individual systems. 

Solar Incentive - Homeowners are offered financial incentives from federal, state, and local governments to install solar systems on their homes. Many solar energy companies also offer their own incentives to homeowners for going solar.


​Solar Installer - When you want to install a solar system, there must be an expert with skills on how to undertake the process. The specialist or company that offers the installation services is the one we refer to as the solar installer.

Solar Lease - A solar lease is a financing option that lets you essentially “rent” your solar panels from a solar leasing company for a set cost each month.

Solar Loan - A loan that allows you to purchase a solar-energy system and pay it off over time with interest


​Solar Monitoring - Monitoring is the process where software is used to track or manage the solar system’s activities. These activities will include power production, usage, carbon offsets, and more.


Solar Panel Or Module - A solar panel is a device that consists of multiple solar cells that connect to form a circuit. Its whole purpose is to absorb sunlight to generate power. It is a single photovoltaic device that comprises an assembly of linked solar cells.


Solar Panel Cleaning - This is the process whereby you remove any build-up materials that may accumulate on top of the solar panels. The natural weather elements like rain can clean up the solar panels, but in some other cases, you have to do it manually as the debris reduces the efficiency of the panels.

Solar Panel Performance Warranty - A performance guarantee from the solar panel manufacturer or installer. An industry leading performance warranty is 30 years.

Solar Panel Product Warranty - A guarantee from the solar panel manufacturer or installer that covers the solar panels. An industry leading warranty is 25 years.

​Solar Power - Solar power is the electricity that comes from harnessing the energy from the sun. The power is generated directly using solar panels, which collects the energy from the sun and converts it into electricity. The conversion of sunlight to electricity can also occur indirectly through concentrated solar power or a combination of the two methods.


Solar Providers - Solar providers are the companies that sell you solar and send licensed installers to your home.


Solar Rack System - Also known as a photovoltaic mounting systems is used to safely fix solar panels to various surfaces such as roofs, building facades, or the ground.


Solar Renewable Energy Credit - For every unit of electricity that a solar system generates, an associated SREC is created. In some states you can sell your SREC's for additional income. 


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Time of Use Rates - Time-of-Use Rates PG&E, SCE, and SDG&E solar customers are required to go on a time-of-use (TOU) rate plan. A TOU rate plan will charge different prices for electricity depending up on the time of day. Prices are typically higher between 4 p.m. and 9 p.m., called “peak” hours, and lower the rest of the day and at night during “off peak” hours.

True South - To gain the maximum energy benefits from the sun, you’ll want your solar panels to face true south (not magnetic south). A solar panel system facing true south will operate at 100% of expectations. An East or West-facing panel will operate at around 80% of expectations. A North-facing panel will only operate at around 60% of expectations.


True-Up Bill/Statement - The annual bill, known as a True-Up Statement, is the net electricity usage for the year and summarizes electricity charges and credits for each month into the annual bill.

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Underproduction - The energy that is generated below the committed level in a customer's agreement


Utility Grid - A utility grid, is a series of an interconnected network which helps deliver electricity t to the final consumer, from the producers.

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Value of Solar - A methodology that takes a uniform approach to establish the true value of the electricity produced by the distributed energy systems.

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Watt - The rate of energy transfer equivalent to one ampere under an electrical pressure of one volt. One watt equals 1/746 horsepower, or one joule per second. It is the product of voltage and current (amperage).

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