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In some remote mountainous areas, scenic spots and islands far away from the large power grid, people often use fuel generators to provide power for the convenience of life. In recent years, with the price of photovoltaic modules, batteries, inverters and other equipment falling, the cost of photovoltaic system has been decreasing year by year, while the fuel price is rising year by year. The installation of photovoltaic power generation system has been the first choice. Photovoltaic power generation and fuel power generation have their advantages and disadvantages. Photovoltaic power generation is environmentally friendly, noise free, low cost of single Watt, but the initial investment is high and affected by weather; The initial investment of fuel power generation is low, it is not affected by weather, but it is not environmentally friendly, and the cost of single watt is high, and there is noise pollution problem, which affects the quality of life. The practice shows that the photovoltaic power generation is the main power generation, fuel power generation is the auxiliary, and the appropriate energy storage system is used, which has better economic and practical.

1-cost analysis of photovoltaic power generation and fuel power generation

The life cycle cost of off grid photovoltaic power generation system = investment cost + operation and maintenance cost + financial cost, and investment cost of off grid photovoltaic system, including purchase cost and installation cost of equipment and materials such as photovoltaic module, battery, inverter, distribution cabinet, support, cable, etc; The operation and maintenance expenses include the salary of operators, maintenance fees for electrical equipment such as inverters, cleaning fees of photovoltaic modules, etc. the operation period of photovoltaic system is generally 20-25 years. The input energy of photovoltaic system comes from the sun. During the operation period, the photovoltaic system does not need other energy, nor generates any residual. There is no vulnerable rotating parts in the photovoltaic system, and the service life of main electrical equipment such as modules is over 25 years, and the maintenance workload of the system is very small, and the annual maintenance cost accounts for about 5% of the system cost. However, photovoltaic power generation is very affected by weather, and cannot be generated in rainy days. Therefore, local weather should be considered in system design. For users who have requirements for power consumption, the days of continuous rainy days shall also be considered.

The life cycle cost of fuel power generation is: the investment cost of diesel power generation mainly includes the purchase cost and engineering cost of diesel generator set and supporting facilities; Fuel cost during the life cycle; The operation and maintenance cost of the unit life cycle mainly includes maintenance cost, oil and other consumables cost in the life cycle of the unit. Among all costs, fuel cost accounts for a relatively large proportion. Generally, the conversion efficiency of fuel generator set generation is about 31%, and the conversion rate group can generate about 3 degrees of electricity for 1 litre diesel oil.

2-10kw oil optical complementary system design case

example

Customer power demand and lighting

The installation site is located on the island, with the main load of lighting, fans and desalination equipment. The load power is 5kW, including 2kW inductive load, 25 degree power consumption in daytime and 15 degrees in the evening. The customer has high requirements for power consumption, and it can ensure that the electricity is available for 5 days in rainy days. The average peak sunshine was 5 hours.

In order to compare the advantages and disadvantages of the optical oil storage system and the optical storage system, we first design a optical storage system, and then design an oil optical storage system to compare the cost.

01

Design of 10kW off grid photovoltaic power generation system

According to the load power of 5kW, 10kW off grid integrated machine is selected for inverter. The customer requires to ensure that the continuous rainy day is 5 days and the daily power consumption is 40 degrees. Therefore, the battery shall use at least 200 degrees of available power. According to the discharge depth of 0.9, the battery needs 220 degree capacity. The components shall meet the demand of 40 degrees per day, and the standby battery shall be charged. According to the local weather conditions, the interval between two consecutive 5 days of rainy days is about 30 days. Therefore, 5 degrees is reserved for the standby battery. The efficiency of the off grid system is about 0.8, and the component needs 12KW. The installation component of the off grid integrated machine itself is 10kW, A 2kW photovoltaic controller is also required.

Cost calculation: 36 340W components, cost 20000 yuan, 10kW off-line integrated machine 10000 yuan, 48v50a controller 2000 yuan, 220 degree lithium battery 400000 yuan, support, cable, installation cost about 16000 yuan, total price of about 450000 yuan.

02

Design of 10kW off grid oil optical complementary power generation system

According to the load, 10kW off grid integrated machine is selected for inverter, fuel generator is used in rainy days for 5 days to ensure power consumption. 12KW diesel generator is used, and 100 liters of diesel oil is reserved. The battery only needs to meet the power consumption at night and 30 degrees of power distribution. The components meet the demand of customers by 40 degrees of electricity consumption in a day. 30 340W components are designed to meet the requirements of customers.

Cost calculation: 30 340W components, cost 18400 yuan, 10kW off grid integrated machine 10000 yuan, 30 degree lithium battery 60000 yuan, support, cable, installation cost about 15000 yuan, diesel generator price 18000, diesel about 600 yuan, total investment about 104000 yuan.

3- scheme design and commissioning

Through comparison, in the area without power grid, photovoltaic system is mainly used in the case of high demand for power consumption and rainy days, and fuel generator is the auxiliary hybrid power supply system. Compared with pure off grid photovoltaic, a lot of expensive batteries can be saved and the power consumption cost can also be reduced a lot. Therefore, the off grid oil optical complementary generation system is designed.

The module is 30 pieces, which is connected to the inverter by 3 strings and 10. The battery bank, load and fuel generator are connected to the corresponding interfaces of the inverter respectively.

During equipment commissioning, the output dry contact function of inverter shall be set as starting generator. When the battery is not enough, the fuel generator shall be started through the dry contact of inverter, and the load shall be supplied by inverter bypass switch.