Detailed explanation of photovoltaic off-grid system solutions
1、Low-cost small off-grid system solutions
Small off-grid system, the main users are from impoverished areas without electricity, remote mountainous areas, herdsmen and tourists, mainly to meet the needs of lighting, mobile phone charging, etc.; the system consumes less than 5 degrees of electricity per day, and the load power is less than 1kW; users The demand for electricity is not very urgent, and the demand for products is simple and reliable, and the price is cheap. Therefore, it is recommended to use a PWM controller and an inverter to correct the wave, and integrate the controller, the inverter and the battery. This method has a simple structure, high efficiency, convenient wiring, and low price. It can drive light bulbs, small TVs, small There is no problem with the fan.
2、Small and medium practical off-grid system solutions
The main users of small and medium-sized off-grid systems come from relatively affluent power-deficient areas, such as herdsmen, island residents, medium-sized fishing boats, relatively remote scenic areas, and some communication and monitoring base stations. It mainly solves the basic needs of life such as lighting, TV sets, fans, and air conditioners; the daily electricity consumption of the system is below 50 kWh, and the total load power is below 20kW; users have certain needs for electricity consumption, and their demands for products are practical and reliable, Inexpensive.
(1) If the user has few inductive loads, it is recommended to use the MPPT controller plus the high-frequency isolation inverter, which is light in weight and cheap; if the user has many inductive loads, it is recommended to use the MPPT controller to process the frequency isolation inverter. The solution is reliable in electricity consumption and can carry shock loads.
(2) If the user’s load power is relatively small, but the electricity consumption time is very long, it is recommended to choose the controller and inverter split scheme, you can choose to use a larger controller and a smaller inverter to increase the power generation, Reduce the system cost; if the user’s load power is relatively large, but the electricity consumption time is not long, it is recommended to choose the integrated solution of the controller and the inverter, and the system wiring is simple.
3、Medium and large-scale reliable off-grid system solutions
Medium and large off-grid systems are mainly used in industrial and commercial areas, scenic areas and other occasions where frequent power outages, high electricity prices, large peak-to-valley price differences, and photovoltaics cannot be connected to the Internet. Main; the system load power is above 20kW and below 250kW, and the daily electricity consumption is below 500 kWh. There are various solutions for small and medium-sized off-grid systems.
For systems above 20kW and below 60kW, you can choose the scheme of connecting multiple single-phase small off-grid inverters in parallel. Relatively speaking, this scheme is more complicated in wiring and debugging, but the price is relatively cheap and the flexibility is high. There is an inverter failure, the system can continue to run. You can also choose the controller and inverter split scheme and the controller and inverter integrated scheme, using a medium and large single inverter, the system wiring is simple, the debugging is convenient, and it can form a hybrid power supply system with the fuel generator set. Compared with pure off-grid photovoltaics, it can save a lot of expensive batteries, and the comprehensive power generation cost is low. For systems above 60kW, there are currently two topologies: DC coupling “DC Coupling” and AC coupling “AC Coupling”, which can be selected according to the power consumption.
