Integrated solution for photovoltaic power generation building

1.Introduction to solar photovoltaic buildings

1.1The application of solar photovoltaic buildings

Solar photovoltaic buildings refer to the combination of photovoltaic power generation with buildings, and the installation of photovoltaic devices on the surface of the building's peripheral structure to generate electricity, thereby generating green energy in the building. There are two ways to combine photovoltaic power generation with buildings, both of which can be connected to the public grid through grid connected inverters, control devices, and the public grid to form a grid connected power generation system.

(1)One method is to combine buildings with photovoltaic systems (as shown in Figure 1), by installing packaged photovoltaic modules (flat or curved panels) on the roofs of residential buildings or buildings to form a photovoltaic power generation system：

(2)Another approach is to combine buildings with photovoltaic devices (as shown in Figure 2), which integrates photovoltaic devices with building materials and directly replaces building materials with photovoltaic devices. This is known as photovoltaic building integration (BIPV), where solar photovoltaic cells are made into photovoltaic glass curtain walls, solar cell tiles, etc. This not only allows for the development and application of new energy, but also integrates them with decoration and beautification to achieve energy-saving and environmental protection effects, It is the trend of developing photovoltaic building integration in the future.

1.2 The advantages of solar photovoltaic buildings

From an architectural, technological, and economic perspective, solar photovoltaic buildings have many advantages, including the following：

(1)It can effectively utilize building roofs and curtain walls without occupying valuable land resources, which is particularly important for urban buildings with expensive land;

(2)It can generate electricity and use electricity in place, saving investment in power station transmission to the grid within a certain distance range. For connected household systems, the electricity generated by photovoltaic arrays can be used to supply the load of the building or sent to the power grid;

(3)It can effectively reduce building energy consumption and achieve building energy efficiency. The photovoltaic grid connected power generation system generates electricity during the daytime when sunlight is shining, which is also the peak period of electricity consumption in the grid, thereby alleviating the peak electricity demand;

(4)Photovoltaic modules are generally installed on the roof and south facade of buildings to directly absorb solar energy. Therefore, integrated photovoltaic power generation systems in buildings not only provide electricity, but also reduce the temperature rise of walls and roofs;

(5)The grid connected photovoltaic power generation system has no noise, no pollutant emissions, and does not consume any fuel. It has the concept of green environmental protection and can increase the comprehensive quality of the building。

1.3 Several installation methods combining photovoltaics with architecture

Financial subsidies will focus on supporting integrated installation of solar photovoltaic buildings and projects where power generation is mainly used to solve building energy consumption. The types of projects mainly include three categories:

One is the building materials type, which refers to the combination of solar cells with building materials such as tiles, bricks, rolls, and glass to form inseparable building components or materials, such as photovoltaic tiles, photovoltaic bricks, photovoltaic roof rolls, glass photovoltaic curtain walls, photovoltaic daylighting roofs, etc;

The second type is component type, which refers to photovoltaic components that are combined with building components or become independent building components, such as canopies and sunshade components composed of standard ordinary photovoltaic modules or customized photovoltaic modules according to building requirements;

The third type is the installation combined with the roof and wall, which refers to the installation on a flat roof, the overhead installation along the slope on a sloping roof, and the installation parallel to the wall on the wall.

2 Introduction to the design scheme of grid connected power generation system

2.1Introduction to Grid Connected Power Generation Methods

At present, the design capacity of the power generation system for solar photovoltaic buildings can range from several thousand watts to several hundred kilowatts, and even up to megawatts. Due to the various forms of photovoltaic and building integration in China, the selection of equipment needs to be optimized according to the actual situation of photovoltaic array installation (such as component specifications, installation direction, etc.), and can be roughly divided into two grid connected power generation methods.

(1)Centralized grid connected power generation

This grid connection method is suitable for installing photovoltaic arrays with the same orientation and specifications on buildings. In electrical design, a single inverter centralized grid connection power generation scheme is adopted to achieve grid connection function, as shown in Figure 3.

(2)Distributed grid connected power generation

This grid connection method is suitable for installing photovoltaic arrays with different orientations or specifications on buildings. In electrical design, photovoltaic arrays with the same orientation and specifications can be centrally connected to the grid through a single inverter for power generation, and a distributed grid connection power generation scheme with multiple inverters can be used to achieve grid connection function, as shown in Figure 4.

2.2Design of photovoltaic array convergence

In order to reduce the number of DC side cable connections and improve the power generation efficiency of the system, large-scale photovoltaic grid connected power generation systems usually require the design of photovoltaic array combiner devices. This device is to concatenate a certain number of batteries into one DC output. The solar photovoltaic power station mainly consists of photovoltaic cell arrays, combiner boxes, low-voltage DC cabinets, inverter cabinets, AC low-voltage cabinets, step-up transformers, etc. The high-voltage AC generated is directly integrated into the power grid. For the needs of power parameter detection in each link, Anker Rui Company has launched the AGF series photovoltaic current collection device, PZ series DC detection instrument, and ACR series power quality analyzer, which are respectively applied in the current collection box, DC cabinet, and AC cabinet, and achieve centralized monitoring in the background through the Acrel-2000 V8.0 photovoltaic power generation monitoring system.

2.2.1APV-M series intelligent photovoltaic combiner box

In photovoltaic power generation systems, a large number of photovoltaic cell modules are combined in series and parallel to achieve the required voltage and current values, in order to achieve optimal power generation efficiency. The main function of the APV-M series intelligent photovoltaic combiner box is to perform primary convergence on the input of the photovoltaic cell array, reducing the connection between the photovoltaic cell array and the inverter, optimizing the system structure, and improving reliability and maintainability. At the same time as providing lightning protection function for convergence, the operating status of the photovoltaic panel, current, voltage, power after convergence, lightning arrester status, DC circuit breaker status collection, relay contact output and other functions were also monitored. The device also has sensor interface functions such as wind speed, temperature, and irradiation instrument for customers to choose from. The device is equipped with RS485 interface as standard, which can upload the measured and collected data to the monitoring system.

2.2.1.1 Product features

◆ Complies with the technical specifications for photovoltaic array combiner boxes in CGC/GF002:2010

◆ The waterproof level is IP65, which meets the requirements for indoor and outdoor installation

◆ The measuring element adopts a Hall sensor to isolate and measure up to 16 inputs

◆ Photovoltaic dedicated fuse, with a withstand voltage of DC1kV and a selectable fusing current

◆ Optional voltage measurement function, with a maximum measurement voltage of DC1kV

◆ Provide external sensor input interfaces for measuring radiation, temperature, wind speed, etc

◆ Equipped with RS485 communication interface and using Modbus RTU communication protocol

◆ Multiple power supply methods (DC24V, AC/DC220V, DC880V) are available for selection, suitable for household rooftop solar energy or large-scale lighting

◆ Photovoltaic specific DC circuit breakers, photovoltaic specific DC fuses, and lightning protection from foreign manufacturers such as ABB can be used according to customer needs

2.2.1.2 Function

◆ Photovoltaic cell string open circuit alarm, status detection

◆ With switch input, used to collect the status of output air contacts of DC circuit breakers, lightning arresters, etc

◆ Equipped with relay output, can be set to jog mode, used to drive the automatic opening and closing of DC circuit breakers

◆ Provide input interfaces for temperature, irradiation, wind speed and other types of sensors

◆ Can output DC24V power supply to external sensors for power supply

◆ On site digital tube displays the input current of each channel in a loop, and has an automatic power-saving display mode that closes automatically

2.2.1.3 Technical Parameter

2.2.2 Photovoltaic power station power monitoring system

Acrel-2000 V8.0 Photovoltaic Power Generation Monitoring System is a software platform developed by Shanghai Ankorei Electric Co., Ltd. for solar power generation systems. It can monitor and control the battery arrays, combiner boxes, inverters, AC/DC distribution cabinets, solar tracking control systems, and other equipment in solar photovoltaic power stations in real time. Through various styles of charts and data, it can quickly grasp the operation of the power station. Its user-friendly interface is user-friendly The powerful analysis function and comprehensive fault alarm ensure the complete reliability and stable operation of the solar photovoltaic power generation system.

2.2.2.1Software functions of photovoltaic power generation monitoring system

● Real time monitoring of the voltage, current, and operational status of solar panels

● Collection and display of lightning arrester status and circuit breaker status

● Real time monitoring of inverter working status and monitoring of its fault information

● Display of detailed operating parameters of the system

● Fault recording and alarm

● Equipped with functions such as battery accumulation, system analysis, and historical recording

● Simple and easy-to-use parameter setting function

● System output current, voltage, instantaneous power generation, cumulative power generation, CO2 and S02 emissions reduction