This article will focus on the common types and characteristics of residential photovoltaic (PV) + energy storage systems.
1. Hybrid Residential PV + Energy Storage Systems
System Introduction
Hybrid PV + energy storage systems generally consist of photovoltaic modules, lithium batteries, hybrid inverters, smart meters, current transformers (CT), the grid, grid-connected loads, and off-grid loads. This system can allow direct charging of the battery via DC-DC conversion from photovoltaic power, as well as bidirectional DC-AC conversion for charging and discharging the battery.
Operating Logic
During the day, photovoltaic generation first supplies the load, then charges the battery, and any excess power can be fed into the grid. At night, the battery discharges to supply the load, while any shortfall is supplemented by the grid. In the event of a power outage, both the photovoltaic system and lithium batteries will only supply power to off-grid loads, and the grid-connected loads will not be available. Additionally, this system supports user-defined charging and discharging times to meet energy needs.
System Features
Highly integrated system, significantly reducing installation time and cost.
Enables smart control to meet user energy demands.
Provides reliable power assurance during grid outages.
2. Coupled Residential PV + Energy Storage Systems
System Introduction
Coupled PV + energy storage systems, also known as AC-modified PV + energy storage systems, generally consist of photovoltaic modules, grid-connected inverters, lithium batteries, AC-coupled storage inverters, smart meters, current transformers (CT), the grid, grid-connected loads, and off-grid loads. In this system, the photovoltaic power is converted into AC through the grid-connected inverter, and any excess electricity is stored in batteries as DC after being converted by the AC-coupled storage inverter.
Operating Logic
During the day, photovoltaic generation first supplies the load, then charges the battery, and any excess power can be fed into the grid. At night, the battery discharges to supply the load, while any shortfall is supplemented by the grid. In case of a power outage, only the lithium batteries will supply power to off-grid loads, and grid-connected loads will not be available. This system also allows users to set their own charging and discharging times according to energy needs.
System Features
Existing grid-connected PV systems can be transformed into storage systems, offering lower investment costs.
Provides reliable power assurance during grid outages.
Compatible with grid-connected PV systems from different manufacturers.
3. Off-Grid Residential PV + Energy Storage Systems
System Introduction
Off-grid residential PV + energy storage systems generally consist of photovoltaic modules, lithium batteries, off-grid storage inverters, loads, and diesel generators. This system can charge the battery directly via DC-DC conversion from the photovoltaic source and allows bidirectional DC-AC conversion for battery charging and discharging.
Operating Logic
During the day, photovoltaic power first supplies the load and then charges the battery. At night, the battery discharges to supply the load, and if the battery is insufficient, the diesel generator can supply power to the load.
System Features
Meets daily energy needs in areas without a power grid.
Can be combined with diesel generators for powering loads or charging batteries.
Most off-grid storage inverters lack grid certification, making it impossible to connect to the grid even if it is available.
4. PV Energy Storage Management Systems
System Introduction
PV energy storage management systems generally consist of photovoltaic modules, grid-connected inverters, lithium batteries, AC-coupled storage inverters, smart meters, current transformers (CT), the grid, and control systems.
System Features
The control system can receive and respond to external commands, adjusting to system energy demands and enabling real-time control and dispatch.
Can participate in optimizing grid operations for more efficient and economical energy use.
Summary
This article has introduced several types of residential energy storage systems currently in common use. With policy support and changing public attitudes, it is believed that more types of energy storage systems will appear in our lives.
