Solar Energy Systems Flashcards

What is the primary function of a bypass diode in a photovoltaic module?

Answer: Prevent reverse current flow through shaded cells

Bypass diodes allow current to flow around shaded or damaged cells, preventing hotspot damage and maintaining power output.

Which solar resource metric best represents the equivalent number of peak sun hours at a site?

Answer: Plane of Array (POA) irradiance

Plane of Array irradiance accounts for panel tilt and orientation and is the most directly relevant metric for estimating energy yield from a fixed PV system.

A string of 12 PV modules each rated at 40V open-circuit voltage is connected in series. What is the maximum string open-circuit voltage?

Answer: 480 V

Series-connected modules sum their voltages, so 12 × 40 V = 480 V open-circuit voltage.

What does a solar inverter's 'anti-islanding' protection do?

Answer: Shuts down the inverter when grid power is lost

Anti-islanding protection automatically disconnects the inverter from the grid during an outage to protect utility workers from unexpected energized lines.

In a grid-tied PV system, what component is responsible for maximum power point tracking (MPPT)?

Answer: Inverter or charge controller

The inverter (in grid-tied systems) or charge controller (in off-grid systems) performs MPPT to continuously extract maximum power from the array.

Which orientation yields the highest annual energy production for a fixed-tilt PV system installed in the continental United States?

Answer: South-facing at latitude angle

South-facing at a tilt approximately equal to the site's latitude maximizes annual solar capture in the northern hemisphere.

What is the purpose of a combiner box in a large PV array?

Answer: Combine multiple string circuits and provide overcurrent protection

A combiner box aggregates multiple PV strings into a single DC output and houses fuses or breakers to protect each string.