NABCEP SH Associate key terms

A structured inventory of every energy use in a building, recording wattage, hours of use, and duty cycle so total daily and peak demand can be estimated before sizing a solar plus storage system.

The manufacturer's stated output for a component, such as module watts at standard test conditions or an inverter's rated AC watts, used as a starting point that real-world conditions will reduce.

The equivalent number of hours per day at 1,000 W/m² irradiance that would deliver the same energy as the actual varying sun exposure at a site; used to convert array size into daily energy production.

Continuous power drawn by devices that are plugged in but not actively performing their main function, such as chargers, set-top boxes, and control boards; these hours accumulate around the clock in a load analysis.

The fraction of time a load such as a refrigerator compressor, well pump, or sump pump actually runs, expressed as a percentage of the total period; essential for realistic energy estimates.

A subpanel fed through a transfer device or backed by storage that contains only the circuits the owner wants powered during an outage, such as refrigeration, well pump, and medical equipment.

The laboratory reference of 1,000 W/m² irradiance, 25 °C cell temperature, and a defined air mass spectrum at which photovoltaic modules are rated and compared.

The percentage change in a module's power or voltage for each degree Celsius away from 25 °C; negative for power, so hot roof surfaces reduce output while cold bright mornings raise open-circuit voltage.

A multiplier below one applied to nameplate output to account for wiring losses, soiling, mismatch, inverter efficiency, temperature, and availability when predicting real system production.

The ratio of actual measured energy output to the theoretical output a perfectly performing array would produce under the same irradiance, used to benchmark commissioning and long-term system health.

The process of identifying and quantifying obstructions such as trees, chimneys, and adjacent buildings that block sunlight on an array across seasons and hours, often using a solar pathfinder or electronic tool.

The compass direction of the sun measured in degrees clockwise from true north, used with altitude to describe where shadows fall and to orient an array toward the equator-facing direction.

The angular height of the sun above the horizon in degrees, lowest at winter sunrise and highest at summer noon, which determines how far shadows are cast across a roof or ground array.

The angle between the array plane and horizontal; steep tilts favor low winter sun and shed snow, shallow tilts favor summer production and reduce wind loading and row spacing.

The horizontal distance between rows of ground-mounted or tilted modules set so that one row's shadow does not fall on the next during the worst winter sun angle of the design period.

Instantaneous solar power density falling on a surface, measured in watts per square meter; distinct from irradiation, which is energy accumulated over time, usually in kilowatt-hours per square meter per day.

The fraction of incoming sunlight reflected by a surface such as snow, white membrane roofing, or dark asphalt; high albedo can add reflected irradiance to bifacial modules or steeply tilted arrays.

A diode wired across a group of cells inside a module that provides an alternate current path when those cells are shaded or damaged, limiting hot-spot heating and preserving the rest of the string's output.

A series diode that permits current in only one direction, preventing reverse current from flowing back into a weaker module or array, commonly used in multi-string and battery charging circuits.

An inverter or charge controller function that continuously adjusts operating voltage and current to keep the array at the point of maximum power as irradiance and temperature change through the day.

The calculation that keeps a series string's cold-temperature open-circuit voltage below the inverter limit and its hot-temperature maximum power voltage above the inverter's minimum, using site temperature extremes.

Applying the module's voltage temperature coefficient to record low and high ambient or cell temperatures to predict worst-case open-circuit voltage and best-case operating voltage for string design.

A required function that reduces conductor voltage within an array to a safe level, typically at or below 80 volts, for firefighters and responders, usually initiated at a clearly labeled switch near the service equipment.

An unintended electrical discharge across a gap in damaged, loose, or degraded conductors or connectors; solar DC circuits require arc-fault detection and interruption to reduce fire risk.

An unintended current path from a live conductor to earth through damaged insulation or water intrusion; inverters and charge controllers must detect and interrupt it to prevent shock and fire.

Bonding non-current-carrying metal parts such as module frames, racking, and enclosures to the grounding system so fault current has a low-impedance path back to the source.

A measurement, usually made with a megohmmeter, of how well a circuit's insulation resists leakage to ground; low readings flag moisture damage or compromised conductor jackets before energizing.

A device that disconnects a building from the utility and connects it to a backup source such as a battery inverter or generator, preventing backfeed that could endanger line workers.

The condition in which a grid-tied inverter continues energizing a circuit while the utility is down; anti-islanding protection is mandatory so the inverter shuts off or transfers to a safe mode.

A solar array synchronized to the utility through an interactive inverter, exporting surplus energy and importing the shortfall, with no storage required but no outage backup without added equipment.

A solar system combining an interactive inverter, battery storage, and often a generator, able to export to the grid while also supplying selected loads during outages or off-grid periods.

A standalone solar and battery system with no utility connection, sized around winter production and consecutive cloudy days, typically using a charge controller and inverter.

A device between the array and battery that regulates charging voltage and current, preventing overcharge and often managing load disconnects; maximum power point tracking types harvest more energy in cool or low-light conditions.

The percentage of a battery's capacity that has been withdrawn; limiting it, for example to 80 percent, extends cycle life and must be reflected in sizing calculations.

The remaining energy in a battery expressed as a percentage of its full capacity, estimated by voltage, current counting, or battery management electronics and displayed to the owner.

Electronics that monitor cell voltages and temperatures, balance cells, and disconnect the battery on fault conditions, protecting lithium and other advanced batteries from damage and unsafe operation.

A photovoltaic module that generates power from light striking both faces, gaining output from ground or roof reflection and requiring careful racking and albedo consideration during design.

A localized overheated cell or connection caused by shading, mismatch, or a failing solder joint, capable of damaging encapsulant and backsheet; bypass diodes and quality connections mitigate it.

An inspection method using a thermal camera to reveal hot cells, loose terminations, and failing diodes in an operating array, often performed during commissioning and periodic maintenance.

The documented verification at project completion that the system is installed as designed and operates safely, including visual inspection, torque checks, polarity, insulation resistance, and performance measurements.

Durable placards identifying disconnects, voltage and current ratings, the rapid shutdown switch, and shock hazards, placed where responders and service personnel can find them quickly.

The rod, plate, or concrete-encased conductor that connects a building's grounding system to earth, providing the reference point for equipment grounding and surge protection.

A conductor that electrically connects metal parts, such as module frames and rail splices, so they remain at the same potential and carry fault current safely.