CSLB C-46 Solar (Trade Exam) — All Questions

What can a grid-forming inverter do that a conventional grid-following inverter cannot?

• a.Operate without any DC source
• b.Ignore the utility's interconnection rules
• c.Restart a grid that went down✓
• d.Raise module efficiency above 40 percent

DOE explains that grid-forming inverters can start up a grid if it goes down, a process called black start, while grid-following inverters need a signal from the grid to match.DOE, Solar Integration: Inverters and Grid Services Basics

Which grid service does DOE say modern inverters can provide?

• a.Converting AC back into sunlight
• b.Raising the utility's retail rate
• c.Providing and absorbing reactive power✓
• d.Storing energy without a battery

DOE notes that modern inverters can both provide and absorb reactive power to help grids balance that resource, one of several grid services advanced inverters can supply.DOE, Solar Integration: Inverters and Grid Services Basics

Which item must appear on an energy storage system's nameplate under the 2022 CEC?

• a.The homeowner's name
• b.Available fault current at the output terminals✓
• c.The date of the next utility bill
• d.The installer's license number

CEC 706.4 requires a nameplate plainly visible after installation, marked with items including the manufacturer, rated frequency, rating in kW or kVA, available fault current at the output terminals, maximum currents and voltages, and utility-interactive capability.County of Lake 2022-code excerpt (CEC 706.4)

Article 706 of the 2022 CEC applies to energy storage systems above what capacity?

• a.More than 20 kWh
• b.More than 1 kWh✓
• c.More than 80 kWh
• d.More than 100 Wh

Article 706 applies to all energy storage systems having a capacity greater than 3.6 MJ (1 kWh). The 20 kWh and 80 kWh figures are residential unit and location limits in the CRC.County of Lake 2022-code excerpt (CEC 706.1)

A new single-family home uses the busbar option to meet the 2022 Energy Code's storage-ready rule. What minimum main panelboard busbar rating applies?

• a.400 amps
• b.100 amps
• c.225 amps✓
• d.150 amps

The 2022 Energy Code's ESS-ready provisions include a main panelboard with a minimum busbar rating of 225 amps, along with other storage-ready measures such as backed-up circuits and space for a transfer switch.County of Lake 2022-code excerpt (Energy Code 150.0(s))

An ESS technology can release toxic gas during normal charging and discharging. Where does the 2022 CRC prohibit it?

• a.Nowhere, if a detector is installed
• b.Within Group R-3 or R-4 occupancies✓
• c.Only on rooftops
• d.Only in commercial warehouses

The 2022 CRC states that ESS with the potential to release toxic or highly toxic gas during charging, discharging and normal use shall not be installed within Group R-3 or R-4 occupancies.County of Lake 2022-code excerpt (CRC R328.12)

Besides converting DC to AC, what does DOE say a household inverter often does?

• a.Monitors the system and communicates data✓
• b.Replaces the need for a disconnect
• c.Stores excess energy for the night
• d.Measures the roof's structural load

DOE notes that a household inverter can monitor the system and provide a portal for communication with computer networks, in addition to converting solar energy into AC power.DOE, Solar Integration: Inverters and Grid Services Basics

Which requirement applies to a power source disconnecting means under 2022 CEC 705.20?

• a.It must be operable only with a tool
• b.It must be hidden inside the inverter
• c.It must plainly show open or closed✓
• d.It must open only the grounded conductor

CEC 705.20 requires the power source disconnect to plainly indicate whether it is in the open (off) or closed (on) position, to open all ungrounded conductors simultaneously, and to be readily accessible and externally operable.County of Lake 2022-code excerpt (CEC 705.20)

Residential ESS installations that exceed the CRC's individual or aggregate energy ratings must follow which code section?

• a.California Fire Code Section 1207✓
• b.California Plumbing Code Chapter 5
• c.The utility's Rule 21 tariff
• d.CEC Article 690 only

The 2022 CRC states that ESS installations exceeding the permitted individual or aggregate ratings shall be installed in accordance with Section 1207 of the California Fire Code.County of Lake 2022-code excerpt (CRC R328 and R328.10)

Which passive solar water heating system stores the water inside the collector itself?

• a.Indirect active system
• b.Integral collector-storage (batch)✓
• c.Evacuated-tube active system
• d.Direct active system

DOE describes integral collector-storage systems as a storage tank covered with transparent material so the sun heats the water in it. Active systems use pumps; ICS systems suit mild-freeze climates.DOE Energy Saver, Solar Water Heaters

In a one-tank solar water heating system, where is the backup heater?

• a.On the roof beside the collector
• b.In a separate tank downstream
• c.There is no backup in one-tank systems
• d.In the same tank as solar storage✓

DOE explains that in one-tank systems the backup heater is combined with the solar storage in one tank; in two-tank systems the solar tank preheats water for a conventional heater.DOE Energy Saver, Solar Water Heaters

How many Btu does it take to heat 40 gallons of water from 60 °F to 120 °F, using DOE's 8.35 pounds per gallon?

• a.About 20,040 Btu✓
• b.About 334 Btu
• c.About 2,400 Btu
• d.About 40,080 Btu

DOE's formula is gallons × 8.35 × temperature rise: 40 × 8.35 × 60 = 20,040 Btu. Leaving out the 8.35 pounds per gallon gives 2,400, which treats water as weighing one pound per gallon.DOE Energy Saver, Estimating the Cost and Energy Efficiency of a Solar Water Heater

What range of collector area does DOE give for solar pool heating, relative to the pool's surface area?

• a.150 to 200 percent of the surface area
• b.Exactly equal to the pool's volume in gallons
• c.50 to 100 percent of the surface area✓
• d.10 to 25 percent of the surface area

DOE says the surface area of the solar collector should equal 50 to 100 percent of the pool's surface area, more in cooler and cloudier areas and less with a pool cover.DOE Energy Saver, Solar Swimming Pool Heaters

How can a solar pool heating system help cool a pool in a hot climate?

• a.By adding glycol to the pool loop
• b.By reversing the pump at noon
• c.By circulating water through them at night✓
• d.By draining the collectors during the day

DOE notes that in hot climates the collectors can cool the pool during peak summer months by circulating water through them at night.DOE Energy Saver, Solar Swimming Pool Heaters

A pool holds 1,500 cubic feet of water. About how many gallons is that?

• a.About 11,220 gallons✓
• b.About 55 gallons
• c.About 1,500 gallons
• d.About 200 gallons

NIST defines a gallon as 231 cubic inches and a cubic foot as 1,728 cubic inches, so one cubic foot is about 7.48 gallons: 1,500 × 7.48 ≈ 11,220 gallons. Fifty-five is the volume in cubic yards.NIST Handbook 44 Appendix C

Which collector has parallel rows of transparent glass tubes and is used more often in U.S. commercial applications?

• a.Thermosyphon batch tank
• b.Evacuated-tube collector✓
• c.Unglazed flat-plate collector
• d.Integral collector-storage unit

DOE describes evacuated-tube collectors as parallel rows of transparent glass tubes, each with an absorber tube and fin, and says they are used more frequently for U.S. commercial applications. Unglazed collectors are typical for pools.DOE Energy Saver, Solar Water Heaters

What median annual degradation rate did NREL's review of nearly 2,000 measured PV rates find?

• a.0.5 percent per year✓
• b.0.05 percent per year
• c.2 percent per year
• d.5 percent per year

NREL's review of nearly 2,000 reported degradation rates found a median of 0.5 percent per year and a mean of 0.8 percent per year, with 78 percent of rates below 1 percent per year.NREL, Photovoltaic Degradation Rates — An Analytical Review

What does NREL say measured PV performance must be compared against to be meaningful?

• a.The installer's sales brochure
• b.A neighbor's electric bill
• c.The module's shipping weight
• d.Expected-performance modeling✓

NREL states that measured performance is meaningful only when compared to a model of expected performance, and lists wire losses, module rating, mismatch, shading, soiling and degradation as factors affecting that model.NREL Best Practices for O&M of PV and ESS

A pyranometer used to calculate a site's performance ratio is covered in dust. What effect does NREL describe?

• a.It has no effect on any calculation
• b.It exaggerates the performance ratio✓
• c.It lowers the array's actual output
• d.It raises the modules' voltage

NREL notes that dirt on a pyranometer will exaggerate the performance ratio, because the sensor under-reports sunlight. The array's actual output is not changed by a dirty sensor.NREL Best Practices for O&M of PV and ESS

What maintenance does NREL recommend for PV modules when cleaning is needed?

• a.Follow the maker's cleaning recommendations✓
• b.Pressure-wash at close range
• c.Use a strong solvent to cut grime
• d.Use abrasive pads to remove film

NREL says to follow the PV module manufacturer's recommendations for any array cleaning, and to clean with plain demineralized water and a mild detergent the manufacturer recommends.NREL Best Practices for O&M of PV and ESS

NREL describes wire management failures on PV arrays. Which cause is named?

• a.Modules that face true south
• b.Plastic ties that break or pinch✓
• c.Conductors that are too large
• d.Inverters that are listed to UL 1741

NREL notes that wire management depends on plastic ties and grommets that can break or pinch wires, and on exposure to sunlight, wind, ice and chewing rodents.NREL Best Practices for O&M of PV and ESS

What does NREL say is a common cause of a ground fault on a PV array?

• a.A wire rubbing a module frame✓
• b.A module facing the wrong direction
• c.A clean irradiance sensor
• d.Too few modules in a string

NREL describes corrective maintenance as finding and repairing ground faults, such as a wire scraping against a module frame, and arc faults caused by a broken wire or loose connection.NREL Best Practices for O&M of PV and ESS

Over a PV array's 25-year life, how many inverter replacements does DOE expect?

• a.One every two years
• b.Exactly five
• c.None
• d.At least one✓

DOE states that inverters are expected to need replacement at least once in the 25-year lifetime of a PV array, which belongs in long-term cost planning.DOE, Solar Photovoltaic System Design Basics

A solar water heater's pump runs during the day but not at night, and hot water production is normal. What does this show?

• a.The collector sensor is shorted
• b.The tank sensor is open
• c.The starting capacitor has failed
• d.The delta-T control is working✓

DOE explains that the delta-T controller starts the pump when the collector is hotter than the tank and stops it otherwise, so daytime-only operation is normal. A pump running at night points to sensor faults.DOE Energy Saver, Solar Water Heating System Maintenance and Repair

A temperature sensor on a solar collector outlet reads far too low. What common problem does DOE point to?

• a.The collector glazing is too clean
• b.The pool cover is missing
• c.The glycol has turned into ethylene glycol
• d.The sensor fell off its surface✓

DOE says a common problem is temperature sensors simply falling off the surface they are meant to measure, and recommends fastening them with a lug or stainless steel clamp.DOE Energy Saver, Solar Water Heating System Maintenance and Repair

What does DOE recommend to remove sediment from a solar storage tank?

• a.Add more glycol to the tank
• b.Flush the tank periodically✓
• c.Raise the collector tilt
• d.Replace the tank every year

DOE recommends flushing storage tanks periodically to remove sediment, and replacing the sacrificial anode in steel tanks at the supplier's recommended interval.DOE Energy Saver, Solar Water Heating System Maintenance and Repair

About how often can regular maintenance on a simple solar water heating system be scheduled, according to DOE?

• a.Every month without exception
• b.Every week
• c.Never; they need no maintenance
• d.Every 3 to 5 years✓

DOE says regular maintenance on simple systems can be as infrequent as every 3 to 5 years, preferably by a solar contractor, and that systems with electrical components usually need a replacement part or two after 10 years.DOE Energy Saver, Solar Water Heaters

A commercial building's 100 kWh lithium-ion ESS is replaced with a new model. How does the 2022 California Fire Code treat the replacement?

• a.As exempt from the fire code
• b.As routine maintenance
• c.As a new ESS installation✓
• d.As a repair needing no permit

The 2022 CFC states that replacements of ESS shall be considered new ESS installations and must meet the section's provisions for new ESS; repairs with non-identical parts are treated as retrofits. These general provisions cover ESS above the 20 kWh lithium-ion threshold outside dwellings; home batteries follow the Fire Code's residential section.County of Lake 2022-code excerpt (CFC 1207.3.8)

What record-keeping does the 2022 CEC require for an energy storage system?

• a.Only a photo of the nameplate
• b.A written maintenance and repair record✓
• c.A monthly utility bill copy
• d.None, if the system is under warranty

CEC 706.7 requires ESS to be maintained in proper and safe condition and requires a written record of system maintenance, including repairs and replacements.County of Lake 2022-code excerpt (CEC 706.7)

An inverter's heat sink is caked with dust. What does NREL's sample annual service schedule include for this?

• a.Clean the heat sinks per the maker✓
• b.Nothing; dust does not affect inverters
• c.Paint the heat sink black to shed heat
• d.Remove the heat sink to improve airflow

NREL's sample schedule includes cleaning dust from inverter heat sinks and cleaning or changing air filters per the manufacturer's warranty requirements, once a year or more often in dusty conditions.NREL Best Practices for O&M of PV and ESS

A solar water heater in a dusty rural area delivers less heat each summer. What simple cause does DOE point to?

• a.Sunlight is weaker in rural areas
• b.Dusty or soiled collectors perform poorly✓
• c.The storage tank is too well insulated
• d.Glycol makes collectors too hot

DOE notes that dusty or soiled collectors perform poorly and that periodic cleaning may be needed where rain does not rinse them, such as near plowing dust or birds.DOE Energy Saver, Solar Water Heating System Maintenance and Repair

What is the maximum arresting force a personal fall arrest system may put on a worker wearing a body harness?

• a.5,000 pounds
• b.3,000 pounds
• c.900 pounds
• d.1,800 pounds✓

Section 1670 limits the maximum arresting force on an employee to 1,800 pounds when used with a body harness. Five thousand pounds is the anchorage strength per employee, not the force on the body.Cal/OSHA Title 8 section 1670(b)

What is the maximum deceleration distance a personal fall arrest system may allow once it begins to stop a fall?

• a.2 feet
• b.10 feet
• c.6 feet
• d.3.5 feet✓

Section 1670 requires a PFAS to bring the worker to a complete stop and limit the deceleration distance to 3.5 feet. Six feet is the maximum free fall before the system engages.Cal/OSHA Title 8 section 1670(b)

How far may a worker free fall when using a positioning device system?

• a.No more than 2 feet✓
• b.No more than 4 feet
• c.No limit, since it is not fall arrest
• d.No more than 6 feet

Positioning device systems must be rigged so that an employee cannot free fall more than 2 feet. The 6-foot limit applies to personal fall arrest systems.Cal/OSHA Title 8 section 1670(c)

A worker shows up with a body belt instead of a full harness for fall arrest on a steep roof. What does Section 1670 say?

• a.Body belts are allowed if the lanyard is short
• b.Body belts are preferred on roofs
• c.Belts may not be used for fall arrest✓
• d.Body belts are allowed below 20 feet

Section 1670 states that body belts shall not be used as part of a personal fall arrest system; they may be used for restraint and positioning within the section's limits.Cal/OSHA Title 8 section 1670(b)

A crew wants to use a spare fall-arrest harness and lanyard to lift a bundle of rails to the roof. Is that allowed?

• a.Yes, if a second worker holds the line
• b.Yes, if the load is under 100 pounds
• c.Yes, if the harness is new
• d.No; harnesses are for employee protection only✓

Section 1670 states that body belts, harnesses and components shall be used only for employee protection and not to hoist materials.Cal/OSHA Title 8 section 1670(b)

Workers are re-roofing a house with a 9:12 roof before a solar installation. At what height must they be protected from falling?

• a.Only above 20 feet
• b.Only above 6 feet
• c.Only above 7 1/2 feet
• d.At any height✓

Section 1731 requires protection on residential roofs steeper than 7:12 regardless of height; the 6-foot trigger applies to roofs of 7:12 or less.Cal/OSHA Title 8 section 1731 (operative July 1, 2025)

When roof jacks support planks on a steep roof, what is the maximum span between jacks?

• a.16 feet
• b.20 feet
• c.6 feet
• d.10 feet✓

Section 1724 states that intervals (spans) between roof jacks shall not exceed 10 feet, and the supported planks must be at least 2-by-6 material or equivalent.Cal/OSHA Title 8 section 1724

What minimum size does Cal/OSHA set for crawling boards used on a roof?

• a.8 inches wide with no cleats
• b.10 inches wide and 1 inch thick✓
• c.6 inches wide and 1/2 inch thick
• d.12 inches wide and 2 inches thick

Section 1724 requires crawling boards not less than 10 inches wide and 1 inch thick, with cleats at intervals not over 24 inches, secured to the roof by ridge hooks or other effective means.Cal/OSHA Title 8 section 1724

At what elevation does Cal/OSHA call for safety nets when fall arrest, restraint and other conventional protection are clearly impractical?

• a.100 feet or more
• b.6 feet or more
• c.25 feet or more✓
• d.10 feet or more

Section 1671 requires safety nets where the elevation is 25 feet or more above the level below and personal fall protection or more conventional protection is clearly impractical.Cal/OSHA Title 8 section 1671

A plywood cover will guard a roof opening during solar work. How strong must it be?

• a.No minimum, if it is marked
• b.At least 100 pounds per square foot
• c.400 lb or twice the load, whichever is greater✓
• d.Strong enough for one worker

Section 1632 requires covers to safely support the greater of 400 pounds or twice the weight of employees, equipment and materials that may be imposed on any square foot, to be secured, and to be marked "Opening--Do Not Remove."Cal/OSHA Title 8 section 1632

How must a worker climb a portable ladder under Cal/OSHA?

• a.Facing away, with both hands on the load
• b.Sideways, with one hand on the rail
• c.Any way, if the ladder is tied off
• d.Facing the ladder, with three points of contact✓

Section 3276 requires the user to face the ladder and maintain contact at three points at all times — two feet and one hand, or two hands and one foot.Cal/OSHA Title 8 section 3276

A worker wants to carry a PV module up a ladder with both hands. What does Cal/OSHA say?

• a.It is allowed if someone steadies the base
• b.It is allowed if the module is under 50 pounds
• c.It is allowed on extension ladders only
• d.Carrying loads that prevent safe ladder use is prohibited✓

Section 3276 prohibits employees from carrying equipment or materials that prevent the safe use of ladders; materials should be lifted by other means.Cal/OSHA Title 8 section 3276

According to the heat illness standard, how long does acclimatization to heat typically take to peak?

• a.One to two hours
• b.One full summer
• c.Four to fourteen days✓
• d.Six to eight weeks

The standard defines acclimatization as temporary adaptation to heat that peaks in most people within four to fourteen days of regular work for at least two hours a day in the heat.Cal/OSHA Title 8 section 3395

During a heat wave, which employees must be closely observed by a supervisor or designee?

• a.Only employees new to the company
• b.Only employees over age 50
• c.All employees✓
• d.Only employees who report symptoms

The heat standard requires all employees to be closely observed by a supervisor or designee during a heat wave, defined as a predicted high of at least 80 °F and at least 10 °F above the prior five days' average high.Cal/OSHA Title 8 section 3395

What form must an employer's Injury and Illness Prevention Program take?

• a.It may be oral in all cases
• b.It is needed only after an injury
• c.It is kept by the customer
• d.It must be in writing✓

Section 3203 requires every employer to establish, implement and maintain an effective IIPP, and the program shall be in writing. Employers with fewer than 10 employees may communicate safe work practices to employees orally.Cal/OSHA Title 8 section 3203

What written document must a construction employer adopt in addition to its IIPP?

• a.A written Code of Safe Practices✓
• b.A copy of the building code
• c.A marketing plan for new customers
• d.A list of approved suppliers

Section 1509 requires every construction employer to adopt a written Code of Safe Practices relating to its operations, posted at the job site office or provided to each supervisor.Cal/OSHA Title 8 section 1509

When do flooded lead-acid batteries produce hydrogen gas, according to Sandia's NEC guide?

• a.Only when completely discharged
• b.At high charge rates or high cell voltage✓
• c.Never; hydrogen is produced only by lithium
• d.Only when frozen

Sandia's guide says flooded, non-sealed lead-acid batteries produce hydrogen when charged at high rates or when terminal voltage reaches about 2.3 to 2.4 volts per cell; confined and unvented, it is explosive.Sandia, PV Power Systems and the NEC: Suggested Practices

When may insulating gloves and insulated tools be omitted for work on exposed energized parts?

• a.Below 250 V, in all cases
• b.Whenever the work lasts under a minute
• c.When the worker is standing on a dry surface
• d.Below 50 V, after a qualified no-hazard determination✓

Section 2320.2 allows omitting approved gloves or insulated tools for parts energized at less than 50 volts only after a qualified person conclusively determines there will be no exposure to shock, burns, explosion or arc hazards.Cal/OSHA Title 8 section 2320.2

A crew runs a portable generator for tools at a job site. Where must it be operated?

• a.Outdoors, at least 5 feet from openings✓
• b.Under the eave, next to a window
• c.Inside the garage with the door open
• d.Anywhere, if it is fueled while running

The 2022 California Fire Code requires portable generators to be operated only outdoors at least 5 feet from building openings such as windows, doors or air intakes, and prohibits refueling while operating.2022 CFC 1204.5 (County of Lake excerpt)