NABCEP SH Associate flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Peak sun hours

Daily solar insolation expressed as equivalent hours at 1 kW/m² irradiance; numerically equals kWh/m²/day and is used to size array output.

Load analysis

Summing appliance wattage times daily hours to compute Wh/day demand, then applying system losses to size the array and battery bank.

Solar window

The portion of the day when the array receives unobstructed sunlight, determined by sun-path and obstruction survey.

Usable roof area

The portion of roof free of obstructions and fire-access pathways, used to determine maximum module count and layout.

Depth of discharge

The fraction of battery capacity that is discharged in normal use; usable capacity equals nominal capacity times DoD.

Continuous load factor

NEC requires continuous loads to be multiplied by 1.25 when sizing conductors and overcurrent protection devices.

Rapid shutdown

NEC 690.12 requirement that PV conductors near the array be reduced to 30 V or less within 30 seconds of shutdown.

Maximum system voltage

Module open-circuit voltage multiplied by the cold-temperature correction factor; must not exceed equipment voltage ratings.

OCPD sizing rule

PV overcurrent protection is sized at 1.25 times Isc multiplied by 1.25, then rounded up to the next standard rating.

Arc-flash hazard

Dangerous energy release from electrical faults; requires arc-rated PPE and incident-energy analysis before energized work.

UL 1741

Standard covering inverters and grid-support functions, including anti-islanding and interconnection requirements for grid-tied systems.

Temperature coefficient

The rate at which module power or voltage changes per degree Celsius; typically negative for power, meaning output drops as cells heat.

Cold-temperature Voc

At low ambient temperatures, module open-circuit voltage rises; use the coldest expected temperature for maximum voltage calculations.

Soiling losses

Energy lost when dust, pollen, or debris covers modules; can reach 5–20 % in arid regions and is reduced by cleaning schedules.

Off-grid autonomy

The number of days a battery bank can supply loads without sun; typically 2–5 days depending on criticality and climate.

Hybrid inverter

An inverter that manages PV, battery storage, and grid interaction, enabling backup power to critical-load subpanels.

Corrosion-resistant racking

Anodized aluminum and stainless hardware specified for coastal or marine sites to resist salt-fog degradation and galvanic corrosion.

True south azimuth

In the northern hemisphere, fixed arrays face true south (180°); deviations of 15–20° typically cost only a few percent of yield.

Optimal tilt

Tilt approximately equal to latitude maximizes annual yield; steeper tilt favors winter production and sheds snow.

Row spacing

Inter-row distance set to avoid shading between about 9 a.m. and 3 p.m. on winter solstice, based on tilt and latitude.

Flush-mount racking

Roof-parallel mounting that minimizes wind uplift and visual impact but reduces airflow and can lower cell cooling.

Clamp zones

Manufacturer-specified locations on module frames where mounting clamps may be attached; clamping elsewhere voids warranty.

Equipment grounding

Bonding module frames and racking to a continuous grounding conductor with listed hardware to clear ground faults safely.

String combiner

A box that parallels multiple PV strings with per-string fuses and a DC disconnect before the inverter.

MPPT controller

Maximum power point tracking charge controller that adjusts operating voltage to harvest maximum array power, especially in larger systems.

DC-rated disconnect

A switch rated for direct-current PV circuits, required because DC arcs do not self-extinguish at zero crossing like AC.

DC/AC ratio

The ratio of array DC nameplate to inverter AC rating; typically 1.0–1.3, allowing clipping but improving low-light output.

PV-rated conductor

Sunlight-resistant, wet-rated wire suitable for outdoor PV circuits, often used with UV-rated conduit and proper strain relief.

Soiling inspection

Scheduled visual check for dust, pollen, and bird droppings; cleaning with water and soft brushes restores output without abrasion.

Hot spot detection

Thermal imaging reveals localized overheating from cell defects, bypass-diode failures, or loose terminations not visible to the eye.

Performance ratio

The ratio of actual to theoretical energy yield; tracking it over time reveals degradation and maintenance needs.

Maintenance log

A record of inspection dates, findings, and corrective actions that supports warranty claims and performance trend analysis.