Understand your solar decisions
Solar terms, explained plainly.
Read your electric bill, understand your proposal, and ask better questions about equipment and backup power.
The solar glossary
Start with the meaning. Follow the decision.
Each entry explains a solar concept through a clear definition, worked examples and the limits that matter when you read a bill or quote. Technical language should help you understand the project, rather than make a proposal harder to compare.
For example, a panel array's power rating, its annual energy production and a battery's stored energy describe different things. Understanding those measurements is a useful first step before choosing system size or backup equipment.
Solar Basics
- PV
Photovoltaics
Photovoltaics (PV) is technology that converts light directly into electricity through semiconductor solar cells.
Read the definition and examples - Solar Basics
Solar array
A solar array, or PV array, is a group of interconnected photovoltaic modules that generates electricity as part of a solar system.
Read the definition and examples - Solar Basics
Solar capacity
Solar capacity is the rated power of a solar installation, stated on a defined DC or AC basis and usually measured in kilowatts or megawatts.
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Solar cell
A solar cell, also called a photovoltaic cell, is a semiconductor device that converts light directly into DC electricity; interconnected cells form the electricity-producing part of a photovoltaic module.
Read the definition and examples - Solar Basics
Solar energy
Solar energy is energy from the sun that can be used as heat or converted into electricity through technologies such as photovoltaic cells.
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Solar panel
A solar panel, also called a photovoltaic module, is a packaged group of interconnected solar cells that converts light into DC electricity.
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Solar Electricity
- Solar Electricity
Alternating current electricity
Alternating current electricity, abbreviated AC, has current whose direction periodically reverses; solar inverters convert photovoltaic DC output for the designed AC connection.
Read the definition and examples - Solar Electricity
Avoided-cost rate
An avoided-cost rate is a compensation rate based on costs a utility avoids by receiving electricity or capacity from another resource under the applicable methodology, tariff or contract.
Read the definition and examples - Solar Electricity
Demand response
Demand response is a change in electricity demand in response to an electricity-system signal, event request or price incentive, under the applicable operating or program conditions.
Read the definition and examples - Solar Electricity
Direct current electricity
Direct current electricity, abbreviated DC, has current flowing in one direction; photovoltaic modules produce DC output, which suitable power electronics can convert for other uses.
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Electrical load
An electrical load is equipment that consumes electrical energy; the term can also describe the power demand of that equipment or a defined group of devices.
Read the definition and examples - Solar Electricity
Grid-tied solar
Grid-tied solar is a photovoltaic system interconnected with the utility electricity grid; its equipment, operating permissions and billing arrangement determine how that connection is used.
Read the definition and examples - kW
Kilowatt
A kilowatt (kW) is a unit of power equal to 1,000 watts, describing the rate of energy generation, transfer or consumption.
Read the definition and examples - kWh
Kilowatt-hour
A kilowatt-hour (kWh) is a unit of energy equal to one kilowatt of power sustained for one hour.
Read the definition and examples - Solar Electricity
Load profile
A load profile is a time-based record or model of electricity consumption or power demand for a defined property, device or group of loads.
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Solar Panels
- Solar Panels
Monocrystalline solar panel
A monocrystalline solar panel is a photovoltaic module using cells made from single-crystal silicon wafers; the term describes crystal structure rather than a particular efficiency, cell architecture, appearance or annual production guarantee.
Read the definition and examples - Solar Panels
Performance warranty
A solar panel performance warranty is a manufacturer’s written promise about minimum output capability over time under specified conditions and remedies.
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Polycrystalline solar panel
A polycrystalline solar panel is a photovoltaic module using silicon cells with multiple crystal grains; also called multicrystalline, it is a material classification rather than a statement of equipment condition, current value or replacement compatibility.
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Product warranty
A solar product warranty is a manufacturer’s written coverage for specified equipment defects, subject to its stated conditions and remedies.
Read the definition and examples - Solar Panels
Solar panel degradation
Solar panel degradation is a reduction in a module’s output capability over time, assessed under comparable measurement conditions.
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Solar panel efficiency
Solar panel efficiency is the ratio of a photovoltaic module’s electrical output to the incident solar power on its defined area under stated measurement conditions.
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Standard test conditions
Standard test conditions are the reference conditions used for photovoltaic ratings: 1,000 W/m² irradiance, 25°C cell temperature and the AM1.5G reference solar spectrum.
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Temperature coefficient
A temperature coefficient describes how a specified electrical characteristic changes with temperature, using a stated unit and reference condition.
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Solar Performance
- Solar Performance
Peak sun hours
Peak sun hours express solar energy received per unit area over a period as an equivalent duration at an irradiance of 1,000 watts per square meter.
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Solar irradiance
Solar irradiance is incoming solar power per unit area on a specified surface, commonly measured in watts per square meter.
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Solar self-consumption
Solar self-consumption is solar electricity used at the property under a stated measurement boundary; its ratio compares that onsite solar use with solar generation over the same period.
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Solar self-sufficiency
Solar self-sufficiency is the share of a property’s defined electricity consumption supplied by its own solar energy, directly or through attributed stored solar energy, over a stated period.
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Solar Installation
- Solar Installation
Permission to operate
Permission to operate is the utility’s authorization for the approved generating system to operate under its interconnection arrangement, subject to the stated equipment, account and operating conditions.
Read the definition and examples - Solar Installation
Roof penetration
A roof penetration is an opening through one or more layers of a roof assembly for an attachment, pipe, cable pathway or other component, requiring a roof-specific detail to maintain the affected water-control layers.
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Solar array azimuth
Solar array azimuth describes the compass direction an array faces, expressed using a stated directional reference and angle convention.
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Solar commissioning
Solar commissioning is the documented process of verifying an installed system against its approved design, equipment instructions and applicable project criteria.
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Solar permit
A solar permit is an approval from the applicable permitting authority for specified solar-related construction or electrical work, subject to its conditions.
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Solar project closeout
Solar project closeout is the documented handover of the installed system, applicable approvals, operating information and owner access, with the status and responsibility for remaining work recorded under the project requirements.
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Solar racking
Solar racking is the mounting assembly that supports, secures and positions photovoltaic modules on a roof, ground support or other approved structure.
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Solar tilt angle
Solar tilt angle is the inclination of photovoltaic modules relative to horizontal; 0° is horizontal and 90° is vertical.
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Utility interconnection
Utility interconnection is the process and approved arrangement for connecting customer generation or storage to a utility’s electrical system under applicable technical, administrative and operating requirements.
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Solar Inverters
- Solar Inverters
DC-to-AC ratio
The solar DC-to-AC ratio divides photovoltaic array DC nameplate capacity by the specified inverter AC rated capacity for the same system boundary.
Read the definition and examples - Solar Inverters
Hybrid inverter
A hybrid inverter combines photovoltaic conversion and battery-related power-conversion or control functions within a supported system; compatible storage and outage operation depend on the exact equipment and configuration.
Read the definition and examples - Solar Inverters
Inverter clipping
In its AC power-limit sense, inverter clipping is the restriction of output when available photovoltaic input could support converted power above the inverter’s applicable output limit.
Read the definition and examples - Solar Inverters
Maximum power point tracking
Maximum power point tracking is electronic control that adjusts photovoltaic operating voltage and current to seek the greatest available power under changing conditions.
Read the definition and examples - Solar Inverters
Microinverter
A microinverter is a solar inverter that converts photovoltaic DC into AC at an individual module or small module group, with the supported input arrangement determined by the product.
Read the definition and examples - Solar Inverters
Power optimizer
A solar power optimizer is DC-side power electronics that adjusts the electrical operating relationship of connected photovoltaic modules; a separate inverter normally performs DC-to-AC conversion.
Read the definition and examples - Solar Inverters
Solar inverter
A solar inverter converts DC electricity from photovoltaic equipment into AC electricity for compatible household or grid use; additional functions depend on its design and configuration.
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String inverter
A string inverter converts DC electricity from one or more series-connected groups of solar modules into AC electricity for the designed electrical connection.
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Solar Batteries
- Solar Batteries
Anti-islanding
Anti-islanding is protection intended to prevent a distributed energy source from continuing to energize an unintended electrical island after separation from the normal utility supply.
Read the definition and examples - Solar Batteries
Backup duration
Backup duration is the time a backup system can support a stated load under defined energy and operating assumptions.
Read the definition and examples - Solar Batteries
Backup gateway
A backup gateway is equipment used in a supported battery system to manage its grid connection and enable an isolated backup supply; its control and metering functions depend on the product and configuration.
Read the definition and examples - Solar Batteries
Battery backup
Battery backup is the function of supplying specified electrical loads from stored battery energy when their normal electrical supply is unavailable, through a system designed for that operating condition.
Read the definition and examples - Solar Batteries
Battery capacity
Battery capacity is a rated storage quantity under specified conditions, expressed as charge in ampere-hours or energy in watt-hours or kilowatt-hours.
Read the definition and examples - Solar Batteries
Battery compatibility
Battery compatibility is whether the identified battery, inverter, controls and installation can operate together as a supported system for the intended functions and conditions.
Read the definition and examples - Solar Batteries
Battery cycle
A battery cycle is a charging and discharging sequence; an equivalent full cycle normalizes partial use against a stated reference capacity using a defined counting method.
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Battery degradation
Battery degradation is a lasting reduction in battery energy capacity or power capability with time and use, assessed against a stated reference under comparable conditions.
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Battery management system
A battery management system is the monitoring and control arrangement that uses battery-condition information to manage supported operation and protection.
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Battery modularity
Battery modularity is the ability to configure or add battery units within a supported manufacturer architecture and the limits of the installed system and site.
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Battery power rating
A battery power rating specifies a supported rate of energy delivery or absorption at a defined boundary, direction, duration and operating condition.
Read the definition and examples - Solar Batteries
Battery reserve
Battery reserve is an allocation or control threshold intended to preserve stored energy for a specified purpose; its charge basis, operating modes and release rules depend on the system.
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Battery throughput
Battery throughput is cumulative energy charged or discharged over a stated period, measured using a defined direction, boundary and equipment scope.
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Continuous battery power
Continuous battery power is the discharge power a battery system can sustain at a stated boundary under specified operating conditions.
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Critical loads
Critical loads are the electrical devices or circuits selected to receive backup power for a stated outage scenario, with priorities, demand and operating requirements defined for that project.
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Critical-loads panel
A critical-loads panel is a distribution panel containing circuits selected to receive power through a supported backup arrangement.
Read the definition and examples - Solar Batteries
Cycle life
Cycle life is the number of defined charge-discharge cycles a battery can undergo before reaching a specified performance threshold under stated test or operating conditions.
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Depth of discharge
Depth of discharge is the percentage of a stated battery capacity removed by discharge, using an identified capacity reference and measurement interval.
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Energy storage system
An energy storage system is an arrangement that stores energy for later use, including the storage medium and the associated equipment and controls required for its intended operation.
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Home energy management system
A home energy management system is an arrangement that monitors or analyzes household energy and, where supported, coordinates electricity use, generation and storage according to defined objectives.
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Islanded operation
Islanded operation is the operation of an electrically separated local power system without its normal connection to the larger electricity grid.
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LFP battery
An LFP battery is a lithium-ion battery using lithium iron phosphate, LiFePO4, as its positive-electrode material; the chemistry label does not specify the complete storage system.
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Load shedding
Load shedding is disconnecting selected loads to keep demand within available supply or another documented operating limit.
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Load shifting
Load shifting changes when electricity is consumed or supplied from storage, moving demand on a particular source from one period to another.
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Peak battery power
Peak battery power is a documented short-duration output capability interpreted with the manufacturer’s time limit and operating conditions.
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Peak shaving
Peak shaving reduces a specified measured maximum electricity demand through load control, generation or energy storage.
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Retained battery capacity
Retained battery capacity is the energy capacity remaining relative to a stated initial or rated reference capacity, expressed in energy units or as a percentage on a consistent measurement basis.
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Round-trip efficiency
Round-trip efficiency is energy returned through a defined storage cycle divided by energy supplied for that cycle, using stated boundaries and comparable starting and ending conditions.
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Solar battery
A solar battery is a rechargeable battery used with solar generation to store energy for later electrical use.
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State of charge
State of charge is an estimate of remaining battery capacity expressed as a percentage of an identified fully charged reference under defined conditions.
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Surge power
Surge power describes short-duration power demand or supported output, interpreted with its stated time limit and operating conditions.
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Usable battery capacity
Usable battery capacity describes energy available within a battery system’s specified operating range and conditions; the manufacturer’s definition determines the included allowances and measurement boundary.
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Solar Costs & Savings
- Solar Costs & Savings
Cost of ownership
Solar cost of ownership is the purchase, financing and other relevant expenses attributed to owning a solar system over an explicitly defined period and scope.
Read the definition and examples - $/W
Cost per watt
Cost per watt is a stated project cost divided by a stated power capacity in watts; solar comparisons need matching cost scope, payment basis and DC or AC ratings.
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Energy offset
Energy offset is solar generation divided by electricity consumption over a defined matching period, usually expressed as a percentage.
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Gross solar cost
Gross solar cost is the identified project price before specified customer incentive deductions, stated with its installation scope, payment basis and document date.
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Levelized cost of energy
Levelized cost of energy, or LCOE, expresses a generating project’s lifecycle costs per unit of energy under a specified analysis period, financial method and energy boundary.
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Minimum bill
A minimum bill is a tariff provision requiring a defined bill amount or group of charges to meet a minimum; its adjustment, eligible credits and relationship to the final amount due depend on the applicable rate and rider.
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Net solar cost
Net solar cost is a stated project cost after explicitly identified adjustments that apply to the customer, with the starting price, eligibility assumptions and timing disclosed.
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Solar return on investment
Solar return on investment is a financial return measure comparing defined net benefits with a stated investment basis over a specified period; its meaning depends on the included cash flows and calculation method.
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Solar Financing
- Solar Financing
Power purchase agreement
A power purchase agreement, or PPA, is a contract to purchase electricity from a specified generating system under agreed pricing and other terms.
Read the definition and examples - Solar Financing
Solar loan APR
Solar loan APR is the annual percentage rate expressing credit cost under the applicable disclosure method; it should be reviewed alongside the loan amount, payment schedule, charges and equivalent cash price.
Read the definition and examples - Solar Financing
Solar loan interest rate
Solar loan interest rate is the contractual percentage used to calculate interest on the relevant loan balance under the stated accrual method; it is distinct from APR, project price and the required payment schedule.
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Solar loan lien
A solar loan lien is a security interest associated with financing a solar purchase; its collateral, filing and transaction consequences depend on the agreement, applicable law and relevant records.
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Solar Incentives
- Solar Incentives
Solar rebate
A solar rebate is a qualifying program payment or cost reduction connected to a solar purchase or participation arrangement; its amount, recipient, timing and conditions depend on the program.
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Solar tax credit
A solar tax credit is an allowed reduction in tax liability for qualifying solar expenditures or activity under a specified tax provision, subject to that provision’s eligibility, limits and timing rules.
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Utilities & Net Metering
- Utilities & Net Metering
Net billing
Net billing is a billing arrangement that separately values electricity purchased from the grid and eligible electricity exported to it after applying the specified netting interval and account rules.
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Net metering true-up
Net metering true-up is a program-defined reconciliation, settlement or reset of accumulated solar billing balances; the period, units, payment and remaining obligations depend on the applicable tariff.
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Solar export rate
A solar export rate is the compensation per eligible unit of electricity delivered to the utility grid under the applicable tariff or contract, with its billing and settlement conditions.
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Time-of-use rate
A time-of-use rate is an electricity rate that assigns different prices to scheduled time periods, with the applicable calendar and account rules defining when each price applies.
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Solar Maintenance
- Solar Maintenance
Solar panel cleaning
Solar panel cleaning is the removal of external deposits from module surfaces using methods consistent with the exact equipment manufacturer’s instructions and the site’s access, condition and work requirements.
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Solar panel inspection
Solar panel inspection is a defined examination of module condition and relevant associated equipment by personnel suited to the agreed inspection scope, with findings and limitations recorded.
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Solar & EV Charging
- Solar & EV Charging
EV charging energy
EV charging energy is the electricity used for charging over a stated session or interval, measured in kilowatt-hours at a specified point such as the charging input or vehicle battery.
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Hardwired EV charger
A hardwired EV charger is charging equipment connected directly to building wiring rather than supplied through a cord plugged into a receptacle; it still uses a separate connection to the vehicle.
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Vehicle-to-home
Vehicle-to-home, or V2H, is a supported arrangement in which energy from an electric vehicle’s battery supplies specified home loads through compatible vehicle, power-conversion and home-interface equipment.
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Commercial Solar
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