98kw Solar Storage and Charging Parking Lot, Nankang District, Ganzhou City

Ⅰ. Photovoltaic Program

1. Project Overview

①Project Location

The project is located in Ganzhou City, Jiangxi Province. Ganzhou City is located in the upper reaches of Ganjiang River and in the south of Jiangxi Province. It has a typical southern subtropical monsoon climate. The geographical coordinates are between 24°29′~27°09′ north latitude and 113°54′~116°38′ east longitude. The annual average temperature is 20.6℃, the annual average daily solar radiation is 3.48kWh/㎡, and the annual solar radiation is 1270.7kWh/㎡. The solar radiation is very rich, which is suitable for laying photovoltaic systems.

This project includes three parts: photovoltaic, energy storage and charging piles. The project installation point is xx, Ganzhou City, and the address is the intersection of Nanshui Avenue and Wenhua Road, Nankang District, Ganzhou City. After on-site investigation, there are no tall buildings around the installation site, and the lighting conditions are good, which is suitable for installing photovoltaics. When there is sufficient sunlight during the day, if the electricity generated by the photovoltaic system cannot be consumed in time, the energy storage system can store the electricity in time and supply power to the charging piles at night.

②Project scale

The project plans to build a photovoltaic carport at the xx parking space, with a total of 30 parking spaces. The photovoltaic carport is paved with photovoltaic modules, and the photovoltaic modules are planned to use 545Wp photovoltaic modules.

The site plan of the parking lot is shown in Figure 1-1. The parking lot has two rows of parking spaces, a total of 30 parking spaces, of which the first row has 16 parking spaces and the second row has 14 parking spaces. The photovoltaic carport can be designed and customized according to the customer's requirements for the height, width and appearance of the carport. Figure 1-2 is a design drawing of a photovoltaic carport for reference.

The photovoltaic modules are laid according to the site plan of the xx parking lot. No maintenance channels are reserved between the photovoltaic modules. The photovoltaic modules use 545Wp photovoltaic modules. The size of each photovoltaic module is 2256*1133mm. A total of 180 photovoltaic modules can be laid, with an installed capacity of 98.1kW. The specific laying diagram is shown in Figure.

Ⅱ. Photovoltaic system solution description

1 Photovoltaic system selection and design

①Photovoltaic module selection

Taking into account the photovoltaic conversion efficiency and power density of photovoltaic modules, the 545Wp single crystal single glass module with high cost performance is selected. This series of modules has the advantages of high power generation, long life, and good reliability. The attenuation in the first year is less than 2%, and the attenuation is 0.55% per year thereafter. The output power is guaranteed for 25 years. The dimensions are shown in Figure 2-1. The detailed technical parameters of the module are shown in Table.

Based on the power requirements of the project's photovoltaic system, taking into account the daily changes in irradiation and the photovoltaic conversion efficiency of photovoltaic modules, a 100kW photovoltaic inverter is selected. This inverter can operate at 1.1 times the rated power for a long time at 45°C, operate at full load at 50°C, integrate PID nighttime repair, and increase system power generation. The specific parameters are shown in Table.

DC
Maximum input voltage	1100V
Minimum output voltage/starting voltage	195V
MPPT voltage range	180-1000V
MPPT number	10
Maximum number of input strings per MPPT	20
Maximum input current	260A (10*26A)
Maximum DC short-circuit current	400A (10*40A)
AC (grid-connected side)
Rated output power	100kW
Maximum output apparent power	110kVA
Maximum output current	132.3A
Rated grid voltage	3/N/PE, 220/380V
Rated grid frequency	50Hz
Power factor	＞0.99 (at rated power)
Total current waveform distortion rate	＜3% (at rated power)
Adjustable power factor range	0.8 leading ~ 0.8 lagging
Efficiency
Maximum efficiency	98.80%
China efficiency	98.20%
Protection
DC reverse connection protection	Yes
AC short circuit protection	Yes
Leakage current protection	Yes
Grid monitoring	Yes
DC switch	Yes
Island protection	Yes
Low voltage ride-through	Yes
String detection	Yes
PID protection and repair	Optional
Surge protection	DC secondary lightning protection/AC secondary lightning protection
General data
Dimensions	1014*567*314.5mm
Weight	82kg
Isolation method	No transformer
Protection level	IP66
Nighttime self-consumption	＜2W
Operating temperature range	-25～+60℃(＞50℃ derating)
Relative humidity	0～100%
Cooling method	Intelligent redundant air cooling
Maximum altitude	4000m
Display	LCD
DC terminal	MC4
AC terminal	OT terminal

2 Photovoltaic array installation type design

Using the internationally used photovoltaic system design software PVSYST to model and analyze the photovoltaic system in Ganzhou, the following results were obtained:

The photovoltaic components are installed in a flat manner, that is, the installation angle is 0°, and each photovoltaic array is densely arranged without maintenance channels. According to the simulation results, it can be concluded that in this case, the total annual solar radiation can reach 1270.7kWh/㎡.year.

3 PV system string design

Based on the technical parameters of the selected PV modules and the historical temperature conditions of Ganzhou (the highest temperature during the day does not exceed 39.7℃, and the lowest temperature is not lower than -8℃), the number of PV modules in series can be calculated according to the following formula:

Umppt_minVpm×1+t'-25×kv≤N≤Umppt_maxVpm×1+t-25×kv

Or

In the formula:

Kv — open circuit voltage temperature coefficient of photovoltaic module;

t — extreme low temperature under working conditions of photovoltaic module;

t′ — extreme high temperature under working conditions of photovoltaic module;

Vdcmax — maximum DC input voltage allowed by the inverter;

Vmppt max — maximum value of inverter MPPT voltage;

Vmppt min — minimum value of inverter MPPT voltage;

VOC — open circuit voltage of photovoltaic module;

Vpm — working voltage of photovoltaic module;

N — number of battery modules in series;

According to the climate environment of the project site, the actual situation of the roof, combined with the temperature correction coefficient of the battery module and the optimal input voltage of the inverter, the number of photovoltaic modules in series is taken as: N=18 after correction and calculation.

According to the above calculation results, the number of photovoltaic modules in series is designed to be 18, that is, the photovoltaic modules of this project are designed according to 18 modules/string to ensure stable operation of the system, and the system operation efficiency is high under normal working conditions. Since a total of 180 photovoltaic modules are laid in this project, a total of 10 strings can be formed,

4 Photovoltaic and electrical access design

A total of 180 545W photovoltaic modules can be laid in the photovoltaic carport of the xx parking lot, with a total installed capacity of 98.1kW. Therefore, a 100kW string inverter is selected. The number of photovoltaic modules in series is 18, and the capacity of each photovoltaic module is 545W, that is, the capacity of each string is 9.81kW. Since the maximum output power of the inverter is 110kW, the inverter can connect up to 11 strings of photovoltaic modules in parallel. The number of parallel strings of photovoltaic modules in this project is 10.

It is planned to add an AC grid-connected cabinet in the site. The grid-connected cabinet is equipped with a switch to control the inverter current. The schematic diagram of photovoltaic access is shown in Figure 2-3. In addition, when selecting cables, considering that the temperature of the outdoor parking lot is high in summer, it is necessary to select cables according to the condition of 40°C.