Home of Photovoltaic Storage | Typical Design of International Medium-Sized PV Microgrid System

Opening remarks: With the national "double carbon" goal, and the construction of new energy as the main body of the new power system and other major development strategies put forward, the new energy industry into a new stage of development. As a "veteran" rooted in the industry for many years, Zonergy will seize this historic development opportunity, accelerate independent research and innovation, and make every effort to create safe and reliable products and solutions, while sharing our thoughts with industry partners and customers. "Every Friday, we will publish our thoughts on the industry and introduce our project design, selection, construction and operation and maintenance cases.

Electricity is an energy source powered by electricity, invented in the 1870s, the invention and application of electricity set off the second industrialization climax. It became one of the three technological revolutions that have occurred in the world since the 18th century of human history, and since then technology has changed people's lives. However, due to the difference in the level of economic development of each country, until today, in some less developed countries and regions, such as Africa and Southeast Asia, remote mountainous areas and islands, far from the large power grid, have not solved the basic electricity problem and cannot enjoy the convenience brought by modern civilization. People often use oil-fired generators to provide power in order to obtain electricity and provide convenience in daily life. With the cost of photovoltaic and energy storage decreasing year by year in recent years, and the price of fuel tends to rise as well as environmental protection factors, PV off-grid power generation system starts to enter people's vision. It is proved that the micro-grid power generation system composed of PV off-grid power generation system and fuel generator set has better environmental protection and economy.

International PV micro-grid project characteristics: With social progress, various countries pay more attention to solving the problem of poor people's demand for electricity, and began to be led by the government, the establishment of photovoltaic micro-grid power station, to solve the problem of electricity, especially large grid imperfect countries, international PV micro-grid project demand is more, the price and payback is usually better. Of course the difficulties are also more: First, the installation site is mostly remote, inconvenient traffic, the transportation and maintenance of products is not easy. Second, there are fewer local PV technicians and training is needed. Third, the customer's electricity equipment situation is complex, the reliability of the product requirements.

The following describes Zonergy's design process for a medium-sized microgrid energy storage in Pakistan.

1、User requirements.

The project is located in a small mountainous village in Pakistan, the power supply radius is about 300 meters, a village is calculated by 100 households, household single-phase 240V/50Hz, the maximum load demand per household is 1kW, the peak load is 1.2kW, the daily electricity consumption is 3kWh; public equipment 415V/50Hz, the load is 10kW, the peak load is 20kW, the daily electricity demand is 30kWh, the average local Sunshine time is 4.2 hours, 30% of electricity is used during the day and 70% at night.

2. Demand analysis.

The total power of household load is 100kW, the spike is 120kVA, judged to be basically resistive load, public equipment 10kW, spike load 20kVA, judged to be partly inductive load, taking into account that the load cannot be turned on at the same time, the maximum spike load of the system is at 120kVA, and the daily electricity consumption is about 330kWh.

3、System design.

The power of micro-grid inverter should be confirmed according to the user's load type and power. The maximum spike load of the system is at 120kW, considering the growth of subsequent users, the inverter adopts the light storage integrated machine with rated power of 150kW, and the output power is 165kVA/150kW, which can meet the customer's demand of 20% growth.

The component power should be confirmed according to the user's daily power consumption, which is about 330kWh per day, and the local average sunshine time is 4.2 hours. Considering the system loss, the design adopts 190 pieces of 540W monocrystalline components, with a total system capacity of 102.6kW and a system efficiency of about 0.8, which can generate 102.6*4.2*0.8, about 345 degrees of electricity per day on average, basically meeting the The current stage of electricity demand, storage inverter PV input using two 50kW charging module, the maximum support for three charging module 150kW PV modules, can support the subsequent customer growth of 50% of electricity demand.

The battery capacity is determined according to the user's electricity consumption when there is no light, because the photovoltaic power generation during the day can be used directly to the load without passing through the battery, the customer's average electricity consumption at night is about 230 degrees, taking into account the safety of the system, and the special weather such as rainy days do not generate electricity, the battery uses 300kWh lithium iron phosphate battery.

4. Electrical scheme design.

540W monocrystalline modules, open circuit voltage 49.5V, operating voltage 41V, operating current 13A, energy storage inverter 150kW, the maximum voltage of 1000V at the PV input, the operating voltage range is 200-850V, lithium battery is rated voltage is 730V, voltage range 570~820 V. The modules are 19 strings of 10 and the string operating voltage is 779V. Close to the lithium battery is the rated voltage, the inverter efficiency is high, using two 5 into 1 out of the sink box, access to the energy storage inverter.

System design features: the use of frequency off-grid inverter control machine, reliable operation, simple wiring, with inductive load capacity. It can reduce the battery configuration and reduce the initial investment. The inverter has 100% unbalanced load carrying capacity, which is convenient to drive single-phase load. Monitoring the voltage, current and insulation resistance of each string, as well as the voltage, current, temperature and remaining power of the energy storage battery, the system operation can be viewed at any time to reduce the generation of faults.

Social benefits: The micro-grid project is invested by the Pakistani government, designed, constructed and operated by Z. The government sells it to residents at a cost price of 0.6 yuan/kWh, which can save residents an average of 62,000 yuan per year in electricity expenses compared to fuel power generation. And PV power generation is stable, no noise and environmental pollution, and lower maintenance cost.

Author：Liu Jimao & Guo Jun

Company Profile

Founded in 2007, Zonergy is a world-renowned provider of integrated solutions for smart microgrids and a national high-tech enterprise. The company is committed to providing first-class smart microgrid solutions for global customers, including technology development and product production, sales and trade, engineering design and implementation, energy management and optimization of wind, water, storage and charging multi-energy complementarity and synergy. After years of development, the company has accumulated strong technical strength, rich engineering experience, formed a first-class technical research and development, engineering implementation and market development team to ensure the development of the company's business in all aspects, the market spreads across most of the domestic regions and overseas countries along the "Belt and Road" and the European market, to provide customers with high-quality solutions and services.

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