100+ Free C-46 Solar Practice Questions

Explanation: For fixed-tilt PV systems in California, tilting modules at an angle approximately equal to the site latitude (38.5° in Sacramento) facing due south maximizes annual solar energy production. Adjusting tilt higher (latitude + 15°) optimizes winter production, while lower tilt (latitude - 15°) optimizes summer production. Facing south captures peak solar irradiance throughout the year.

Explanation: California Title 24 Joint Appendix JA2 specifies that a solar zone on a building roof must have an unshaded Solar Access Fraction (SAF) of at least 70%. The SAF represents the percentage of total annual solar insolation available at the site compared to an unshaded location. Shading analysis tools like solar pathfinders or digital shade meters are used to verify compliance.

Explanation: Standard flush-mounted residential PV module and racking installations add approximately 2.5 to 4.0 lbs/sq ft of dead load to the roof structure. The California Building Code (CBC Chapter 16) requires contractors to verify that existing roof rafters or trusses can support this added dead load along with applicable live, wind, and seismic loads without structural retrofit.

Explanation: The DC-to-AC ratio (also called inverter loading ratio) is calculated by dividing total DC array capacity by inverter AC power rating: 10.0 kW DC / 7.6 kW AC = 1.315 (rounds to 1.32). Designing with a DC/AC ratio between 1.15 and 1.35 is common practice in solar design to maximize inverter energy production during low-light hours despite minor peak clipping.

Explanation: CEC Section 690.8(A)(1) requires maximum current to be calculated as 125% of module Isc (10.0 A x 1.25 = 12.5 A). Section 690.8(B)(1) then requires conductor ampacity and OCPD sizing to be at least 125% of that maximum current (12.5 A x 1.25 = 15.625 A, or 156.25% of Isc). Therefore, 10.0 A x 1.5625 = 15.63 Amps.

Explanation: Per CEC 690.7, maximum PV voltage must account for lowest ambient temperature. Temperature difference is 25°C - (-5°C) = 30°C drop. Voltage increase percentage is 30°C x 0.30%/°C = +9.0%. Maximum Voc = 40.0 V x (1 + 0.09) = 43.60 V per module. This corrected voltage ensures string Voc will not exceed inverter or equipment voltage ratings.

Explanation: California's Net Billing Tariff (NEM 3.0) significantly reduced export credit values compared to retail rates. This change incentivizes pairing PV systems with Energy Storage Systems (ESS) so customers store excess daytime solar energy for self-consumption during peak evening hours rather than exporting low-value power to the grid.

Explanation: CEC Section 705.12(B)(2) (the 120% rule) permits total breaker ratings supplying a busbar to equal 120% of busbar rating: 200A x 1.20 = 240A total. Subtracting the 200A main breaker leaves 240A - 200A = 40A maximum allowable PV backfeed breaker rating at the opposite end of the busbar.

Explanation: For solar domestic hot water systems in California, rule-of-thumb sizing allocates approximately 10 to 15 square feet of flat-plate collector area per household occupant. For a family of 4, a total collector area of 40 to 60 sq ft paired with an 80-gallon storage tank provides 60% to 80% annual solar fraction.

Explanation: Most manufacturer engineering guidelines for residential flush-mount racking permit attachment spacing on every other rafter (48 inches on center) under typical California wind speeds (110 mph exposure B/C). High-wind or snow load zones may require 24-inch spacing, but 48-inch spacing is standard for estimating lag screw attachment layout.