Core Knowledge (20%)

PVA · 60 questions

• A homeowner with a 6-kW rooftop system wants phone alerts for low production and a monthly energy report, while the installer wants remote fault codes without a site visit. The site has Wi-Fi and a revenue-grade meter on the inverter. Which monitoring equipment function best meets both needs for this home?
• A training lab has four small demo boards: a fan wired straight to a module, a shed light with battery and no grid, a house array that shuts off with the grid, and a house array with battery backup. Which statement correctly distinguishes PV direct, stand-alone, grid-tied, and multimode systems?
• A homeowner has reliable grid power, wants daytime bill savings with net metering, has no batteries, and needs shutdown when the grid fails for lineworker safety. The trainee must label the design file correctly. Which system type label describes this battery-free grid-linked configuration?
• A new residential PV owner reports high bills despite a working inverter display showing power today. The O&M tech needs remote history of energy, alerts, and string trends to diagnose without a site visit. Which description best states the role of monitoring equipment in this system?
• A trainee confuses a fan wired straight to a module, a cabin with batteries and no grid, a suburban net-metered roof, and a suburban roof with backup batteries. Which concept check distinguishes PV direct, stand-alone, grid-tied, and multimode systems by storage and grid ties?
• A new O&M helper checks a 20-kW commercial rooftop where the owner wants phone alerts for low output, string-level fault location, and proof of monthly savings without opening electrical gear. Which monitoring equipment description best meets these visibility needs?
• On a ground-mount service call, an apprentice sees bare copper to frames, a lug to a ground rod, and a jumper between metal boxes and asks what each part does for fault safety. The lead must clarify paths without quoting code text. Which answer best distinguishes grounding and bonding elements EGC, GEC, electrode, and jumper?
• On a residential rooftop retrofit, the installer bonds module frames to rails and runs a wire from the rail to the main grounding bus, which ties to a ground rod. The lead confuses the rail wire with the rod wire. Which grounding and bonding distinction correctly names EGC, GEC, electrode, and bonding jumper for this system?
• A family on a reliable grid wants lower bills plus lights and fridge through short outages, keeps a small utility link, and can house a battery in the garage. Budget allows one inverter and storage. Which system type fits this backup-plus-savings customer scenario?
• A farm family wants daytime power for a remote pump with no utility lines, no need for night use, and the lowest cost and upkeep. A vendor proposed batteries and a backup generator. Which system type match fits this customer scenario with cost and maintenance limits?
• A trainee wires a residential rooftop system where module frames must link together, the inverter case needs fault protection, and a ground rod ties the system to earth through a continuous conductor with jumpers around lugs. Which grounding and bonding element choice correctly separates EGC, GEC, electrode and jumper?
• A rural clinic needs vaccine refrigeration through frequent multi-day grid outages, has space for batteries, and can fund storage for critical loads only. Fuel delivery is unreliable. Which system type match best fits the customer scenario for backup and daily solar use?
• A rural health clinic loses grid power twice each winter for 6-10 hours and needs vaccines refrigerated and lights on. It has rooftop PV but no storage and shuts down during outages. Which system feature should the associate describe first to explain energy security through reliability and resiliency?
• A new installer asks why a silicon module makes DC power in daylight with no moving parts. You explain the cell has p-type and n-type layers forming a junction, photons strike the silicon, and meter leads read voltage and current. Which description correctly explains the photovoltaic effect behind this reading?
• A new installer asks why a silicon module makes DC power with no moving parts during a toolbox talk in Denver. The crew works with crystalline modules rated near 40 Voc and wants the physics, not sales terms. Which statement correctly explains the photovoltaic effect for this entry-level crew?
• A rural clinic director worries about multi-day storm outages spoiling vaccines and closing exam rooms. The site has a grid-tied PV array with no storage, and staff ask how solar helps security. Which explanation correctly describes reliability and resiliency for this site?
• A new helper on a 8-kW home install asks why the modules produce DC power in full sun even though they stay relatively cool to the touch in a breeze. Which explanation of the photovoltaic effect best answers that question?
• A rural clinic with frequent evening outages considers a 25-kW PV array with battery storage to keep vaccines cold and lights on. Leaders ask how solar helps security beyond lower bills. Which explanation best describes reliability and resiliency for this clinic?
• During commissioning of a 6-kW residential string in Boise you read 240 Vdc and 20 Adc at the inverter input on a clear cool morning. The lead asks you to verify expected DC power and check consistency with meter readings. Which application of Ohm's law and power relationships correctly validates the operating point?
• A first-time buyer in a suburb asks a salesperson why neighbors added rooftop PV when grid rates keep rising and wildfire smoke fills skies each August. The home has good sun and net metering. Which explanation best links predictable cost and environmental benefit?
• A trainee measures a residential string at 380 V and 9 A at midday and must verify expected power and check whether a 10-A series fuse rating leaves safe margin before calling the lead. Which application of Ohm's law and power relationships best completes this check?
• A school board hesitates on a 200-kW rooftop PV bid because utility rates rose 4% yearly and parents ask about air quality near a gas plant. The system has 25-year performance coverage. Which benefit of predictable electricity cost and environmental gain should the associate explain first?
• A school board weighs a 100-kW rooftop to stabilize a tight operating budget and meet climate goals, asking what solar delivers beyond kilowatt-hours. Which explanation best captures predictable electricity cost and environmental benefit for this school?
• During commissioning of a 6-kW string inverter you measure 240 volts AC at the point of connection while the system exports 24 amps to a resistive test load. The lead wants power and circuit resistance confirmed from these readings. Which Ohm's law and power calculation gives the correct values?
• A homeowner with a 5-kW rooftop system says the monitoring app showed 4 kW at noon and 20 kWh for the day, and asks why the two numbers differ when both describe system output on a clear day with no outage. Which explanation correctly distinguishes power (W) from energy (Wh) for this PV system?
• A homeowner sees a 6-kW array rating and a monitor showing 24 kWh made Tuesday, and asks why the numbers differ while comparing a 300-W panel to a battery storing 10 kWh. Which statement correctly distinguishes power (W) from energy (Wh) for this customer?
• A suburban homeowner with high daytime air-conditioning use and frequent evening outages asks how a 7-kW rooftop system without storage helps bills and the grid on sunny afternoons. Which description should the associate give to explain economic benefits and distributed generation?
• A homeowner asks why rooftop solar helps household bills and the local grid when a large distant plant could make cheaper power. She has high afternoon peak rates and frequent summer congestion. Which economic benefit best describes distributed generation for this customer?
• A homeowner asks why rooftop solar plus staying tied to the grid helps household bills and the local feeder with evening peaks and daytime solar surplus. Which description of economic benefits and distributed generation answers correctly?
• A new salesperson tells a homeowner with a 400 W module quote that the system will make 6,000 W per day, mixing ratings and bills that show kWh use. The manager asks for a correction before proposals go out. Which statement correctly distinguishes power (W) from energy (Wh)?
• A new hire asks why a 400-W glass-backsheet module on rails needs clamps at set zones and a small gap to the roof. Which description should the trainer give to describe PV modules and mounting structures?
• A sales designer must explain to a client why two same-wattage quotes differ when one uses glass-backsheet modules on rail mounts and the other uses glass-glass modules on shared-rail low-slope mounts. Which description of PV modules and mounting structures is correct?
• A ground-mount client worries about wind uplift, module cracking, and future swaps, asking how panels and racks share loads and allow service. Which description of PV modules and mounting structures answers best?
• During a rooftop O&M visit, one string in a 24-module array reports zero current at the combiner while its neighbors read normal. The array is in full sun with the DC disconnect closed, and a meter across that string's inline fuse reads a distinct voltage while the same test across a healthy fuse reads almost nothing. Which fault do the readings pinpoint at that fuse?
• A technician measures a residential string at midday and reads 410 V open-circuit as expected, but voltage sags sharply when loaded and one connector feels warm. Resistance across that section reads high. Which interpretation of voltage, current, resistance and impedance measurements best explains the readings?
• An apprentice checks two identical inline fuse holders on a DC string carrying 9 A at midday: across one the meter reads 0.02 V and across the other 2.8 V, while both points read 0 V after sunset when the array produces nothing. Which interpretation of these voltage-drop readings is best supported?
• A homeowner has partial chimney shade, wants panel-level monitoring, and may add batteries later for backup. The sales rep offers string, central, micro, and multimode choices. Which inverter comparison should the associate present to match shade tolerance and future battery backup?
• A developer compares options for a 600-kW open-field plant on one flat site with uniform sun, three-phase service, and a central electrical room for easy service access. Which inverter comparison correctly matches string, micro, multimode, and central inverters to this project?
• A new sales rep shadows you on a home with rooftop DC strings feeding an inverter that exports AC to the panel, asking why both types exist. The inverter display shows DC volts in and AC volts out. Which comparison of AC and DC behavior should the associate give to explain solar power flow?
• A trainee sees DC from modules entering a string inverter and AC leaving to a home panel, the crew debates why an inverter is needed, and the foreman asks for a clear distinction for safety and metering. Which statement comparing AC and DC best guides safe handling and system understanding?
• An entry-level tech is checking a working rooftop string wired to a string inverter that feeds a home panel. Morning readings show steady polarity at the module leads and a cycling sine at the panel feed. The lead asks why two meters are needed for one sun source. Which electrical comparison of AC and DC correctly explains the readings and test approach?
• A builder is comparing bids for eight townhomes with mixed roof faces, light chimney shade, and a request for panel-level data with no batteries and minimal single-point outage risk. The lots share one service trench. Which inverter comparison should the designer present to match string, micro, multimode, and central types to this need?
• A retrofit adds a shaded dormer string to a high-voltage residential inverter, and the local code requires module-level rapid shutdown with shade-tolerant harvest on the affected roof face. Which power electronics choice correctly explains rapid shutdown devices and DC-to-DC converters for this need?
• A trainee is assigned to a small home with a 120/240V panel and later to a shop with a 208V three-phase panel. Both sites have PV breakers, but conductor counts, neutral use, and phase relationships differ. The mentor asks what service is present before landing wires. Which circuit comparison among single-phase, split-phase, and three-phase best identifies each service?
• An associate must explain service options to a homeowner with 120-V lights and 240-V well pump, and to a shop with 208-V motors fed from three hot legs. The meter tags are unclear. Which circuit comparison of single-phase, split-phase, and three-phase supply should the associate give to guide equipment choice?
• A service tech is upgrading a 6-kW string array that needs NEC rapid shutdown at the modules and has one chimney-shaded string losing morning output, with no batteries planned and the existing inverter kept. Which power electronics choice explains rapid shutdown devices and DC-to-DC converters for this retrofit?
• A junior designer reviews three services: a small cabin with 120 V lighting, a suburban home with 120/240 V appliances, and a warehouse with 208 V motors, and must explain wiring and power differences to the crew. Which comparison of single-phase, split-phase and three-phase circuits best fits each site?
• A rooftop crew wires a 12-module string to a string inverter where the plan calls for module-level rapid shutdown and one shaded module needs voltage boosting. Which power-electronics choice should the associate verify to meet shutdown and DC-to-DC conversion needs?
• A trainee tests a small off-grid demo with four identical 40-V, 10-A modules. First all four are wired in series, then rewired as two series strings of two modules in parallel. Which paired circuit value correctly shows the series versus parallel result for comparison?
• A small farm shop runs a grid-tied solar array with a battery bank and a smart panel for freezers and well pumps. The owner asks why power stays on after sunset and why freezers stay cold while shop tools shut off during a low-charge event. Which statement best describes energy storage and load control roles?
• You wire four identical 42-V open-circuit, 11-A short-circuit modules for a small off-grid test, first all in series then all in parallel, using ideal values and ignoring losses. The charge controller has strict voltage and current limits. Which calculated result correctly shows series versus parallel circuit values?
• A homeowner's hybrid inverter provides backup to part of a 200 A main panel from a fully charged battery with 10 kWh usable capacity, and the budget leaves no room for extra battery capacity. During evening outages the inverter carries the 4.5 kW water heater and 7 kW EV charger without any power limit, yet the battery runs dry in about an hour and the fridge goes dark. The fridge, lights, and router together average 0.5 kW, and outages typically last 10 hours until sunrise. Which load-control change will keep the fridge and other critical loads powered until sunrise?
• On a shed demo board a trainer has three identical 42-V open-circuit, 9-A short-circuit modules feeding one fused homerun. Trainees must predict meter readings before covering and uncovering modules. Which series versus parallel circuit calculation correctly predicts total voltage and current for the demo?
• A rural clinic wants lights and vaccine refrigeration to ride through nightly outages, with daytime PV often exceeding demand and staff forgetting to turn off extra loads. The designer proposes batteries plus automated switching. Which energy storage and load control role description should the associate use to explain system functionality?
• An apprentice wires a small grid-tied rooftop system from array to main service and asks what each box and run does. The run uses roof conduit to a fused disconnect, then to the main panelboard with a backfed breaker and an overcurrent device sized for the wire. Which description correctly identifies balance-of-system parts?
• During a class demo an instructor faults a 48-V battery rack where the grounded conductor and the metal case bonds look identical to students. Which explanation correctly distinguishes system grounding from equipment grounding and bonding for this setup?
• You explain to a new installer why a small string-inverter home has a grounded DC conductor tied to earth and also green equipment wires bonding frames, rails, and enclosures. The site has lightning exposure and a service grounding electrode. Which explanation correctly distinguishes system versus equipment grounding and bonding?
• An associate is labeling a residential supply-side job with modules, inverter, and battery already tagged, and must identify the remaining balance-of-system parts for the as-built: main panelboard, fused disconnect, metal conduit run, PV conductors, and breaker protection. Which statement best identifies balance-of-system parts and their roles?
• A helper is kitting parts for a 20-kW rooftop to inverter run and asks which items count as balance-of-system beyond modules and inverter. The run needs a main tie-in, service isolation, raceway, wiring, and fault protection. Which balance-of-system grouping should the lead identify for panelboards, disconnects, conduit, conductors, and overcurrent devices?
• During a walk-through at a small warehouse PV system with a grounded DC array, a trainee traces two conductors landing on the grounding bar at the system's designated bonding point: a green wire from the metal combiner enclosure, and the array's negative conductor, marked with white tape. The electrician says one connection is equipment grounding and the other is system grounding. Which statement correctly describes what each connection does for safety and normal operation?