Home »Blog» Optimizing solar photovoltaic power supply systems and petroleum generators
In some parts of the world, the power grid may fail or shut down due to unstable power supply or planned shutdown through procedures such as "load shedding", and may last for an unknown period of time. During this period, the standard grid-connected solar photovoltaic system will also be closed. How do we ensure that solar photovoltaic systems continue to work during these temporary but usually long power outages?
This Solis seminar brings you a solar photovoltaic + diesel generator complementary system. We will study the actual installation and how it works.
Solution 1: A power system with low capacity, stable load and no sudden high demand period.
The operation of the generator can be managed through the inverter's own settings and intelligent adaptability.
The system topology is shown in Figure 2. The inverter manages a virtual grid composed of diesel generator systems through self-adaptation and adjustment capabilities. The solution is simple and stable, and does not require additional equipment or cost.
The setting and adjustment of the inverter are as follows:
In order to promote green energy production and gradually realize the mission of “carbon peak and carbon neutrality”, China will implement strict electricity curtailment measures in 2021, and many high-energy-consuming factories will be affected.
The example here is an electrical appliance manufacturer based in Ningbo, Zhejiang Province. The company has a 1MW solar photovoltaic power station, using 17 Solis 60kW 4G grid-connected inverters, and they are connected to the grid at 4 grid-connected points.
Affected by limited power, some power plants were out of power, and grid-connected photovoltaic systems were shut down. This affects the power supply demand of the assembly line workshop by approximately 270kW. Solis engineers worked with the company to directly install a 350kW diesel generator system using 3 x 60kW inverters for independent work on site. The output power of the photovoltaic + power generation system is 150kW, and the maximum photovoltaic utilization rate of the load reaches 50%, achieving the goal of saving fuel costs.
This solution can reduce the electricity cost per kilowatt-hour in the form of photovoltaic + generator through the adaptive adjustment capability of the inverter. However, there are scenarios where the ratio of photovoltaic capacity should not be too large and the load must be constant. This scheme is not suitable for situations with large load fluctuations. The photovoltaic capacity ratio needs to be less than 40% of the total power supply to ensure the stability of the system.
Solution 2: Power system with large burst load
These usually require a high proportion of on-site photovoltaic capacity (above 70%), and need to introduce system control and communication equipment to adjust the balance between solar photovoltaic, generator and load.
The solution uses DEIF's AGC controller and Solis inverter for coordinated control. It supports up to 16 380V low-voltage grid-connected solar inverters and 1 or 2 diesel generators. It can support multiple working modes such as on-grid, off-grid/on-grid combination, etc. Therefore, it has greater scalability and flexibility, and is the system choice for many remote areas, island areas, and areas with little or no stable power grids.
This example is located in Brazil and uses DEIF's AGC_150 hybrid controller to integrate and control a 500kW solar photovoltaic system. The solar system uses Solis 25kW low-voltage inverters, and then merges into a virtual grid composed of a 500kW diesel generator system to supply power to the factory's 430kW load.
In the case of sufficient sunlight, solar photovoltaic can provide up to 360kW of electricity, accounting for more than 70%.
This solution can effectively coordinate and manage the output of inverters and generators in the system by introducing additional controllers to meet load power consumption. It can also maximize the use of the energy generated by the photovoltaic system to reduce fuel energy consumption. Therefore, the system is more stable and can adapt to the application scenarios of sudden load changes. The solar photovoltaic capacity can provide 70% to 80% of the total power, which can realize a megawatt-level power supply system.
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