This project designs a 252kW photovoltaic ionization grid system to supply power to the living load of rural areas in the rainforest of the Republic of Suriname, South America.

The load is expected to be mainly for simple household electrical equipment such as televisions and lighting facilities, with the main electricity consumption periods expected to be 5:00-7:30, 18:00-20:00, and sporadic electricity consumption during the day.

The technical support party for this project is JDSOLAR, a Chinese brand specializing in the development of solar energy.

The project is located in the Republic of Suriname, South America, with latitude and longitude coordinates of 5 degrees 52 north and 55 degrees 14 west. Suriname has a tropical rainforest climate with an average annual temperature of 23-27 ° C and an annual rainfall of over 2000 millimeters. The local climate is divided into rainy and dry seasons. From early February to the end of April each year, it is the dry season with the lowest temperature, with an average of 22 ° C, making it the golden season; The rainy season is from the end of April to mid August; The period from mid August to early December is the major dry season, while the period from early December to early February of the following year is the minor rainy season. The northern part has a tropical grassland climate. Suriname is located outside the hurricane zone and is free from major natural disasters.

The project is located in the Republic of Suriname, South America, with latitude and longitude coordinates of 5 degrees 52 north and 55 degrees 14 west. Suriname has a tropical rainforest climate with an average annual temperature of 23-27 ° C and an annual rainfall of over 2000 millimeters. The local climate is divided into rainy and dry seasons. From early February to the end of April each year, it is the dry season with the lowest temperature, with an average of 22 ° C, making it the golden season; The rainy season is from the end of April to mid August; The period from mid August to early December is the major dry season, while the period from early December to early February of the following year is the minor rainy season. The northern part has a tropical grassland climate. Suriname is located outside the hurricane zone and is free from major natural disasters.

During the day, under sunlight, solar panels convert solar energy into direct current. After multiple solar cell arrays are gathered through a combiner box, the photovoltaic controller charges and manages the battery pack. As the load is an AC device, it is necessary to use an off grid inverter to reverse the direct current of the photovoltaic array or battery into alternating current, Then adjust the output voltage to the universal voltage level (128V~220V) in South American countries through an isolation transformer. During nighttime or rainy weather, the diesel generator set is responsible for power supply.

The design of this project adopts high-efficiency, multiple cycles, and small footprint ternary lithium batteries as energy storage modules (lead carbon batteries can be considered for later construction plan optimization, which have higher cost-effectiveness and product characteristics more suitable for the climate conditions of Suriname). The design capacity is designed for power generation on a rainy day, with a preliminary configuration of 348 12V 240AH ternary lithium batteries, with a capacity of about 1002kWh. The actual discharge capacity is about 900kWh/day.

Number of batteries=installed capacity (W) * local sunshine index (H)/discharge depth/battery voltage (V)/battery capacity (AH)=900 * 280 * 3.5/0.9/12/240=340 (nodes), combined with the voltage level of the controller and inverter, finally 348 nodes are selected for design.

Ternary polymer lithium battery: Refers to a lithium battery that uses lithium nickel cobalt manganese or lithium nickel cobalt aluminate as the positive electrode material. There are many types of positive electrode materials for lithium-ion batteries, mainly lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium iron phosphate, etc. The battery with lithium iron phosphate as the positive electrode material has a long charging and discharging cycle life, but its disadvantages are that there is a significant gap in energy density, high and low temperature performance, and charging and discharging rate characteristics, and the production cost is high. The technology and application of lithium iron phosphate battery have encountered development bottlenecks; Lithium manganese oxide batteries have low energy density。

The cycling stability and storage performance at high temperatures are poor, so lithium manganese oxide is only used as the positive electrode material for the international first generation power lithium batteries; Multivariate materials, due to their dual advantages of comprehensive performance and cost, are increasingly being paid attention to and recognized by the industry, gradually surpassing lithium iron phosphate and lithium manganese oxide as the mainstream technology route. At present, ternary battery cells have replaced the previously widely used lithium cobalt oxide battery cells and are widely used in the field of notebook batteries.

The energy is relatively high. It has a high storage energy density, reaching 460-600Wh/kg, which is about 6-7 times that of lead-acid batteries;

Long service life, with a service life of over 8 years. The battery with lithium ferrous phosphate as the positive electrode is charged and discharged at 1C (100% DOD), with a record of being able to be used 10000 times;

The self discharge rate is very low, which is one of the most prominent advantages of this battery. It can generally achieve less than 1% per month, less than 1/20 of that of nickel hydrogen batteries; Lightweight, with a weight of approximately 1/6-1/5 that of lead-acid products in the same volume; It has strong adaptability to high and low temperatures and can be used in environments ranging from -20 ℃ to 60 ℃. After processing, it can be used in environments ranging from -45 ℃.

Lead acid battery (VRLA) is a type of battery with electrodes mainly made of lead and its oxides, and the electrolyte is a sulfuric acid solution. In the discharge state of lead-acid batteries, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; In the charging state, the main component of the positive and negative electrodes is lead sulfate.

The lifespan of lead-acid batteries is greatly affected by the depth of discharge, and the focus of design considerations is on deep cycle use, shallow cycle use, or floating charge use. If shallow cycle batteries are used for deep cycle use, lead-acid batteries will quickly fail.

The deeper the discharge depth, the shorter the cycle life.

Overcharging the battery can shorten the application period.

The battery life increases with increasing temperature within a certain temperature range because the capacity increases with increasing temperature. If the discharge capacity remains unchanged, the discharge depth decreases and the solid life extends as the temperature increases.

The increase in acid density is beneficial for the capacity of the positive electrode plate, but the increase in self-discharge of the battery and the acceleration of grid corrosion also promote the loosening and detachment of lead dioxide. With the increase in acid density used in the battery, the cycle life decreases.

As the discharge current density increases, the lifespan of the battery decreases, as under high current density and high acid concentration conditions, the positive electrode lead dioxide loosens and falls off.

After comparing the performance of two types of batteries, it was found that although lithium batteries are slightly higher in unit price than lead-acid batteries, they have significant advantages in deep cycle times, cycle life, volume and weight, and have cost advantages in power station operation and maintenance.

Note: Regardless of the type of battery used, a separate battery room (or divided into areas within the mechanical and electrical equipment room) needs to be established for specialized management. Air conditioning can be used to adjust the temperature and humidity accordingly.

Based on the load situation, this project selects a single phase off grid inverter and an RF-UK33250-SPO-A model off grid inverter, which adopts advanced IGBT power devices, high-performance SPWM inverters, and rich power management software. It is a product specifically developed for new energy power generation. Suitable for areas with strict reliability requirements for power supply such as non electrified mountainous areas, pastoral areas, border defense, islands, etc., such as heat dissipation, insulation, and long-distance transportation problems caused by large temperature differences between day and night, thin air at high altitudes. Product features:

Output with isolation transformer

Digital DSP Control Technology

Powerful Chinese and English LCD display interface

Flexible networking monitoring

Reliable electromagnetic compatibility characteristics

Intelligent fan control

The utility backup function is optional, and can be set as either utility priority or solar priority

Optional high-power charging function

Allow three-phase 100% unbalanced operation

Adapts to all loads and can operate with an electric motor

According to data, Suriname is in the midst of rainy seasons for 7 months of the year, with a humid climate and a tropical rainforest climate. Based on the future maintenance work of the project, it is recommended to use ternary lithium batteries. This battery has characteristics such as long cycle life, good chemical stability, and high temperature resistance. Moreover, lithium batteries have a good undercharge cycle life and do not need to be fully charged every time after discharge, making them very suitable for off-grid power stations in this project. The Republic of Suriname in South America belongs to a tropical rainforest climate, with humid air and soft ground soil. This off grid project requires high performance indicators such as material, corrosion resistance, wind resistance, and strength of the support. In response to the above characteristics and requirements, our company has designed and selected a double column fixed bracket (LK-G-001) type hot-dip galvanized bracket (in the later construction plan, considering the strength and support of the bracket based on on-site investigation, the optimization plan can use aluminum alloy brackets, which are more suitable for the climate conditions of Suriname).

Product Description:

1. The distance between piles is 2.9 meters, the distance between adjacent groups is 1.3 meters, and the distance between intermediate piles is 4 meters;

2. The length of the C-shaped steel string is 6.13X3=18.39 meters, with a spacing of 0.31 meters between the two strings;

3. 40 battery modules in a string, with a string length of 18.24 meters;

4. The reserved size at both ends of the C-shaped steel string is 0.075 meters longer than the reserved size of the component.

5. All rods shall be hot-dip galvanized after rust removal (grade: Sa2.5 (St3)), and the thickness of the galvanized layer shall not be less than 80 μ M.

Technical parameters:

1. Installation location: outdoor ground

2. Wind resistance of 35m/s, customizable according to customer requirements

3. Design snow pressure 1.4kN/m2

4. Support material Q235B

5. Quality assurance design with a service life of 25 years and a quality assurance of 5 years

Product features:

1. The appearance is simple and atmospheric, with light unit weight and cost saving.

2. Exquisite structure, few components, convenient installation, improving on-site installation efficiency.

3. Diversified application, strong combination, suitable for various environments.

4. Maintenance free, strong wind resistance, and all types of brackets have undergone strength testing and simulated pull-out testing