Practice Test Geeks(REP) Certified Renewable Energy Professional Practice Test
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Storage and Grids Flashcards

7 cards from real REP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What is the primary function of a Battery Management System (BMS) in a grid-scale BESS?

    Answer: Monitoring cell-level voltage, temperature, and state of charge to protect battery health

    The BMS monitors and balances individual cell parameters (voltage, temperature, SOC, SOH) to prevent overcharge, over-discharge, and thermal runaway.

  2. Which metric describes the ratio of actual energy delivered by a storage system over its lifetime to the total energy input over the same period?

    Answer: Round-trip efficiency

    Round-trip efficiency (RTE) is cumulative energy out divided by cumulative energy in over the system's lifetime, capturing all conversion and parasitic losses.

  3. A utility operates a grid with high solar PV penetration. Which grid challenge most commonly emerges during the transition from midday high-solar to evening high-demand periods?

    Answer: Steep ramping requirement known as the duck curve

    The duck curve describes the steep net-load ramp that occurs in the late afternoon as solar generation drops while evening demand peaks, requiring fast-ramping resources.

  4. In FERC Order 841, what action did the Federal Energy Regulatory Commission take regarding energy storage?

    Answer: Required grid operators to allow energy storage to participate in all capacity, energy, and ancillary services markets

    FERC Order 841 (2018) directed RTOs/ISOs to remove barriers and establish rules enabling electric storage resources to participate fully in wholesale electricity markets.

  5. What is the purpose of reactive power compensation provided by grid-tied inverters in renewable energy systems?

    Answer: Maintaining voltage stability by supplying or absorbing reactive power (VARs)

    Reactive power (VARs) support from smart inverters helps maintain voltage within acceptable limits, especially on long distribution feeders with high renewable penetration.

  6. Which type of compressed air energy storage (CAES) plant uses the heat generated during compression to improve round-trip efficiency?

    Answer: Adiabatic CAES

    Adiabatic CAES captures and stores compression heat in a thermal energy storage medium and reuses it during expansion, significantly improving efficiency over diabatic designs that vent the heat.

  7. What grid topology connects multiple microgrids and distributed energy resources through a shared medium-voltage backbone, enabling both islanded and grid-connected operation?

    Answer: Networked microgrid

    A networked microgrid architecture interconnects individual microgrids at a shared bus, allowing power sharing among nodes and collective islanding from the utility grid.