Solar Energy System Design & Installation Flashcards

Which type of PV module technology generally has the highest conversion efficiency in standard laboratory and commercial production today?

Answer: Monocrystalline silicon (mono-Si)

Monocrystalline silicon modules currently achieve the highest commercial conversion efficiencies, typically 20–24% for premium products.

What is the purpose of a PV system's 'interconnection agreement' with the utility?

Answer: It establishes technical and contractual terms under which the PV system may connect to and operate in parallel with the grid

An interconnection agreement specifies the technical requirements, protective functions, and legal terms governing the parallel operation of a distributed generation system with the utility grid.

A homeowner reports that their 6 kW PV system produced 7,200 kWh in its first year. What is the system's capacity factor?

Answer: 13.7%

Capacity factor = 7,200 kWh / (6 kW × 8,760 hours/year) = 7,200 / 52,560 ≈ 13.7%.

Under NEC 690.64, when a PV system is connected to the load side of a service panel, what rule governs the maximum allowed inverter breaker size relative to the bus bar rating?

Answer: The sum of all supply-side breaker ratings must not exceed 120% of the bus bar rating

NEC 690.64(B) allows the sum of all overcurrent device ratings feeding the bus to reach 120% of the panel's bus bar rating when the PV breaker is at the opposite end from the main breaker.

What is the main function of a maximum power point tracker (MPPT) in a PV inverter?

Answer: To continuously adjust the electrical operating point of the PV array to extract maximum power under varying conditions

An MPPT algorithm dynamically varies the array's operating voltage to find the point on the I-V curve where power output is maximized under current irradiance and temperature.

Which of the following best describes the purpose of a 'system design pressure test' for a solar thermal (not PV) collector loop?

Answer: Confirming that all piping joints are leak-free by pressurizing the system above operating pressure

A pressure test applied above normal operating pressure checks all pipe joints, fittings, and connections for leaks before the system is filled with heat-transfer fluid.

When using a string inverter on a roof with multiple orientations, which design approach best minimizes production loss due to mismatched strings?

Answer: Use a multi-MPPT inverter and connect strings of the same orientation to separate MPPT inputs

A multi-MPPT inverter allows each orientation's string to operate at its own independent maximum power point, preventing a well-exposed string from being dragged down by a shaded or differently oriented string.