What is on-grid solar power system and off-grid solar power system

1.Diagram of solar off-grid power generation system

Solar off-grid power generation system

The application scope of solar off-grid power generation system is to provide you with all needed life electricity, especially suitable for mountain villages without electricity, schools, hospitals, private houses, islands in frontier defense, team and field operation, etc.

Components and Functions of a Solar Off-Grid Power Generation System

A solar off-grid power generation system consists of solar panels, a solar controller, and a battery (bank). If the output power is AC 220V or 110V, an inverter must also be installed. The functions of each component are as follows:

• Solar panels: Solar panels are the core component of a solar power generation system. Their function is to convert solar energy into electrical energy, either storing it in the battery bank or powering the load.
• Solar Controller: The solar controller regulates the system's operational status and provides overcharge protection and over-discharge protection for the battery bank. It also features temperature compensation functionality. Additional features may include light-controlled switches and time-controlled switches.
• Battery Bank: Typically lead-acid batteries, their function is to store the electrical energy generated by the solar panels during daylight hours and release it when needed.
• Inverter: When providing 220VAC or 110VAC AC power is required, since the direct Output Of Solar Panels is typically 12VDC, 24VDC, or 48VDC, a DC-AC inverter is needed to convert the DC electricity generated by the solar power system into AC electricity to supply power to 220VAC appliances. In certain situations where multiple voltage loads are required, a DC-DC inverter is also needed, such as converting 24VDC power into 5VDC power (note that this is not a simple voltage reduction).

When designing a solar power generation system, it is essential to consider multiple key factors comprehensively to ensure the system's efficiency and reliability. First, it is necessary to identify the specific region where the system will be deployed (including country, state, and city), and obtain the latitude and longitude information of that region. This will help determine the intensity and duration of solar radiation, which in turn will influence the system design and capacity. Next, the total amount of electricity the system needs to provide daily must be calculated, typically measured in kilowatt-hours (kWh) or watt-hours. This will directly impact the number and configuration of solar panels. Additionally, the system's maximum load power must be considered, along with whether it needs to provide direct current (DC) or alternating current (AC), and the corresponding inverters and other key components must be selected. Finally, to address unpredictable weather changes, such as prolonged rainy periods, the system's batteries must have sufficient capacity to sustain power supply for several days. Overall, these factors collectively determine the design, scale, and cost of the solar power generation system.

2.Diagram of solar on-grid power generation system

Photovoltaic grid-connected power generation systems convert solar energy into electrical energy without storing it in batteries. Instead, they directly feed the electrical energy into the grid via a grid-connected inverter. Photovoltaic grid-connected power generation represents the future direction of photovoltaic power sources and is one of the most promising energy utilization technologies of the 21st century. Grid-connected inverters utilize maximum power point tracking (MPPT) technology to maximize the amount of electrical energy from photovoltaic cells that is fed into the grid.

A photovoltaic grid-connected power generation system consists of photovoltaic modules, grid-connected inverters, metering devices, and a distribution system. Solar energy is converted into direct current (DC) power by photovoltaic modules, which is then converted by the grid-connected inverter into sinusoidal current with the same frequency and phase as the grid. Part of this power supplies local loads, while the remaining power is fed into the grid.  The grid-connected inverter uses an internal power regulator to maximize the amount of electricity fed back into the grid from the solar cells. Since the grid itself can absorb a large amount of energy, the grid-connected power generation system does not require additional batteries, thereby reducing system investment and maintenance costs, and offering broad application prospects!

Components and Functions of a Solar On-Grid Power Generation System

Grid-connected photovoltaic power generation systems primarily consist of the following components:

• Photovoltaic array: including solar cell modules, support structures (such as frames and foundations), junction boxes, cables, and wires;
• DC-AC inverter equipment: including DC panels, distribution cabinets, grid-connected inverters, etc.;
• Step-up grid-connected facilities: including step-up transformers, outdoor vacuum circuit breakers, high-voltage surge arresters, etc.;
• Control and monitoring system: including system control devices, data monitoring, processing, and display systems, remote information exchange equipment, etc.;
• Auxiliary facilities: lightning protection and grounding protection devices, photovoltaic field cleaning equipment, workshops and offices, protective fences, pathways, and roads, etc.