Technical characteristics of solar panels

It is designed according to the requirements of IEC: 1215:1993 standard of International Electrotechnical Commission, and the processing and production process is produced in strict accordance with the standard, which can ensure the quality, electrical performance and service life requirements of solar panels.

1) The insulation strength of the solar panel is greater than 100m Ω

2) The service life of the product exceeds 25 years.

3) Operating temperature range: – 40 ℃ ~ + 85 ℃.

The surface of the solar panel is made of composite materials and laminated by a laminator. Good air tightness, weather resistance, corrosion resistance and mechanical strength. Double grid lines are adopted to improve the reliability of solar panel packaging.

When manufacturing solar cells, chemical treatment is carried out first, and the surface is made into a pile like a pyramid, which can reduce reflection and better absorb light energy.

ABS plastic junction box is adopted, with good aging resistance, waterproof and moisture-proof performance. The bypass diode can reduce the damage caused by local shadow. 36 or 72 single crystal or polycrystalline silicon solar cells are connected in series to form various types of 12V and 24V solar panels. Solar panels consist of the following materials:

1) Solar cells. High efficiency (more than 14.5%) monocrystalline silicon or polycrystalline silicon solar cell chip packaging is adopted to ensure the output power of solar panel design.

2) Glass. Low iron tempered suede glass (also known as white glass) is adopted, with a thickness of 3.2mm. The transmittance is more than 91% in the wavelength range (320 ~ 1100nm) of solar cell spectral response, and has high reflectivity for infrared light greater than 1200nm. At the same time, the glass can withstand the radiation of solar ultraviolet light without reducing the transmittance.

3) EVA、TPT. A high-quality EVA film with a thickness of 0.78mm is added to the UV resistant agent, antioxidant and curing agent as the sealant of the solar panel and the connection agent between glass and TPT. It has high transmittance and anti-aging ability.

The back of the solar cell is covered with white fluoroplastic film, which reflects the sunlight. The solar cell layers are made of double-layer EVA material and TPT composite material. The module has good air tightness, moisture resistance, UV resistance and is not easy to aging.

The solar panel using the above materials can slightly improve the efficiency of the solar panel. Because it has high infrared reflectivity, it can also reduce the working temperature of the solar panel and improve the efficiency of the solar panel.

Of course, the fluoroplastic film used should have the aging resistance, corrosion resistance and airtightness required by the solar cell packaging material. The basic requirements for solar panels are:

1) The aluminum alloy frame adopted shall have high strength and strong mechanical impact resistance.

2) Standard test conditions: (AM1.5) the irradiance is 1000W / m2 and the battery temperature is 25 ℃.

3) Insulation voltage: ≥ 600V.

4) Frame grounding resistance: ≤ 10 Ω.

5) Upwind pressure: 2400pa.

6) Filling factor: 73%.

7) Temperature coefficient of short-circuit current: + 0.4ma / ℃.

8) Open circuit voltage temperature coefficient: – 60mV / ℃.

9) Operating temperature: – 40 ℃ ~ + 90 ℃.

At present, there are two main packaging forms of solar panels. One is the “glue dropping plate” encapsulated with epoxy resin with high transparency, and the other is encapsulated with “low iron” tempered glass, which is called “laminate”. Laminated solar panels have high production costs, complex processes and long service life, and their service life in normal use is more than 25 years.

The glue dropping plate has the advantages of flexible production size, low cost, short production cycle and fast production speed. Its biggest disadvantage is that the solar cell has light effect aging, fast attenuation, poor performance stability and short service life. Although the glue dropping package has a beautiful appearance, the working life of the solar cell plate is only 1 ~ 2 years.

Key points of grid-connected solar panel array selection

The grid-connected solar photovoltaic power generation system has different characteristics from the off-grid solar photovoltaic power generation system. When there is sunlight, the solar photovoltaic power generation system feeds the power grid. When the solar photovoltaic power generation system cannot meet the power demand of the load on cloudy and rainy days or at night, the load is switched to the power grid.

In this way, there is no problem of waste of power generation in summer and insufficient power supply to load in winter due to improper selection of inclination angle. In the grid-connected solar photovoltaic power generation system, the only problem that needs to be concerned is how to select the best inclination angle to maximize the annual power generation of the solar cell array.

The selection of the best inclination angle of a solar panel array in a grid-connected solar photovoltaic power generation system shall be comprehensively considered according to the actual situation, and the restrictions on the installation location of the solar panel array shall be considered.

Especially for photovoltaic building integration (BIPV) project, the selection of inclination angle of solar panel array shall also consider the beauty of the building, the inclination angle needs to be adjusted in a small range according to the actual needs, and this adjustment should not lead to a significant reduction in solar radiation absorption.

When the grid-connected solar photovoltaic power generation system is connected to the grid, the solar panel array must realize the maximum power point tracking control, so that the solar panel array can continuously obtain the maximum power output under any current sunshine. When designing the number of solar panel arrays in series, the following points should be paid attention to:

1) The specification, type, series number, and installation angle of solar panels connected to the same photovoltaic inverter shall be consistent.

2) The temperature coefficient of the optimal working voltage (VMP) and open-circuit voltage (VOC) of the solar panel shall be considered. The VMP of the solar panel array in series shall be within the MPPT range of the photovoltaic inverter, and the VOC shall be lower than the maximum value of the input voltage of the photovoltaic inverter.

For monocrystalline silicon and polycrystalline silicon solar panels, the temperature coefficient of operating voltage (VMP) is about -0.0045 / ℃ (equivalent to 0.8 at 70 ℃); The temperature coefficient of open-circuit voltage (VOC) is about -0.0034 / ℃ (equivalent to 1.12 at – 10 ℃).

For amorphous silicon thin-film solar cells, the temperature coefficient of operating voltage (VMP) is about -0.0028 / ℃ (equivalent to 0.874 at 70 ℃); The temperature coefficient of open-circuit voltage (VOC) is about -0.0028 / ℃ (equivalent to 1.1 at – 10 ℃).