Here is a summary of commonly used terms related to photovoltaics (PV) and energy storage:

PV-related terms

• Photovoltaic Cell: The core component of a photovoltaic (PV) power generation system, capable of converting solar energy into direct current (DC) electricity, operating through the photovoltaic effect.

• Photovoltaic Module: A collection of multiple PV cells connected in series or parallel; the basic unit of a PV power generation system.

• Inverter: A device that converts DC power into AC power. In a PV power generation system, it is used to convert the DC power generated by the PV module into AC power that meets grid requirements.

• Maximum Power Point Tracking (MPPT): A technology used to adjust the operating point of a PV module in real time, ensuring it always maintains maximum power output.

• Grid-connected: The PV power generation system is connected to the public power grid, injecting the electricity generated by the PV system into the grid for grid-connected power supply.

• Off-grid: The PV power generation system operates independently of the public power grid, typically used in remote areas or areas without a power grid.

• Standard Test Conditions (STC): Ambient temperature 25℃, atmospheric mass AM1.5, wind speed 0m/s, 1000W/㎡ conditions. Primarily used for laboratory testing of photovoltaic module performance.

• Rated Cell Operating Temperature (NOCT): The temperature reached when the solar module or cell is in an open-circuit state, under the conditions of (cell surface light intensity = 800W/㎡, ambient temperature = 20℃, wind speed = 1m/s). The NOCT for normal modules is 45℃±2℃.

• Building Integrated Photovoltaics (BIPV): Integrating solar cells with building materials, directly applying them to the building envelope such as roofs and walls, serving not only a power generation function but also a building function.

Energy Storage Related Terms

• Energy Storage System (ESS): A system used to store and release electrical energy. Common energy storage devices include batteries and supercapacitors.

• Battery Energy Storage System (BESS): A system that uses lithium-ion or lead-acid batteries as energy storage carriers to store and supply electrical energy for a certain period of time. It features functions such as smoothing transitions, peak shaving and valley filling, and frequency and voltage regulation.

• Battery Cell: A single battery cell, the smallest unit of a battery system.

• Battery Module/Pack: A standard package of a series of individual batteries.

• Battery Rack/Cluster: An energy storage unit composed of a series of battery modules.

• Battery Collection Panel (BCP): Located between the battery rack and the energy storage inverter, similar to a photovoltaic DC combiner box.

• Power Conversion System (PCS): A bidirectional DC-AC inverter, the core component that enables bidirectional flow of electrical energy between the energy storage system and the grid. It controls the charging and discharging process of the batteries, performing AC-DC conversion.

• Battery Management System (BMS): Intelligently manages and maintains individual battery cells, preventing overcharging and over-discharging, extending battery life, and monitoring battery status.

• Energy Management System (EMS): An intelligent system integrating hardware and software, used to monitor, control, and optimize energy flow and consumption in energy systems. Based on data acquisition, analysis, and decision support technologies, it can monitor the operating status of energy equipment, energy consumption, and environmental conditions in real time, thereby achieving efficient energy management and optimization.

• Cycle Life: The lifespan of a battery during charge-discharge cycles, usually measured by the number of charge-discharge cycles or the depth of cycles. Batteries with high cycle life can be used for a longer period, reducing the cost and time of battery replacement.

• Thermal Runaway: Battery damage caused by uncontrolled internal temperature during charge-discharge processes.

• Charge/Discharge Rate (C-Rate): The discharge rate refers to the current required to discharge its rated capacity within a specified time; it is numerically equal to a multiple of the battery's rated capacity. That is: Charge/discharge current (A) / Rated capacity (Ah), typically measured in C (short for C-rate), such as 0.5C, 1C, etc.

• Guaranteed Power Capacity (GPC): The minimum capacity released by the energy storage system within a specified usage period.

• Round-trip Efficiency (RTE): The ratio of the total amount of electricity released from the AC terminal when the battery is fully charged to the amount of electricity required to fully charge the AC terminal, after considering equipment losses and self-consumption during charging and discharging.

Related Terms for Photovoltaic + Energy Storage Systems

• Residential Energy Storage: An energy storage system used by residential users, usually installed in conjunction with a residential photovoltaic system to provide electricity to the household. Its working principle is that during the day, photovoltaic power is prioritized for use by the load, and excess energy is stored in batteries. If there is still surplus electricity, it can be selectively fed into the grid. At night, when the photovoltaic system is not operating, the battery discharges to supply local loads.

• Dynamic Capacity Increase: By installing energy storage systems, energy is stored and discharged during transformer overload periods, reducing transformer load and thus lowering the cost of transformer capacity expansion. Energy storage systems not only significantly reduce costs but also increase revenue through peak-valley arbitrage.

• Photovoltaic-Storage-Direct-Flexible (PEDF): This technology applies four technologies to the building sector: photovoltaics, energy storage, direct current distribution, and flexibility.

• Virtual Power Plant (VPP): This technology aggregates various distributed adjustable power sources and loads, forming a virtual "power plant" for unified management and dispatch, while also participating in the electricity market. Virtual power plants are well-developed in developed countries in Europe and America.

• Vehicle to Grid (V2G): This technology enables interaction between electric vehicles and the power grid, allowing electric vehicles to absorb energy when grid load is low and release energy when grid load is high.

These terms cover the main technologies and concepts of photovoltaic and energy storage systems, helping to better understand the principles and operation of photovoltaic + energy storage systems.