Solar Panels for Major Components of Photovoltaic Power

The solar panel assembly is made of imported (or domestically produced) monocrystalline (or polycrystalline) silicon solar cells in series and parallel, and is heat sealed with tempered glass, EVA and TPT. The periphery of the solar panel assembly is equipped with an aluminum alloy frame, which has the characteristics of strong wind resistance, hail resistance and easy installation. Solar panels are widely used in solar lighting, lamps, household power supply, highway transportation, construction and photovoltaic power stations.

 

Power generation principle

The working principle of crystalline silicon n / p-type solar cells: When a p-type semiconductor and an n-type semiconductor are tightly combined into one piece, a p-n junction is formed at the interface between the two. When photovoltaic cells are illuminated by sunlight, positive and negative charge accumulations are formed on both sides of the p-n junction, generating a photo-generated voltage and forming a built-in electric field. This is the “photovoltaic effect”. In theory, at this time, if the electrodes on both sides of the built-in electric field are drawn out and connected to a suitable load, a current will be formed and power will be obtained on the load. Solar cell modules are solid-state devices that use the electronic characteristics of semiconductor materials to achieve P-V conversion.

Component composition

Tempered glass

Low-iron tempered glass (also known as white glass), with a common thickness of about 3.2 millimeters, and a light transmittance of more than 90% in the wavelength range of the solar cell’s spectral response (320-1100NM). Reflectivity. The glass is also resistant to UV radiation and the light transmittance does not decrease.

The tempering performance complies with the national standard GB9963-88 or the package’s impact resistance meets the performance indicators specified in the national standard GB9535-88 ground silicon solar cell environmental test method.

EVA

EVA is a hot-melt adhesive with a thickness between 0.4 mm and 0.6 mm. The surface is flat, the thickness is uniform, and it contains a cross-linking agent. It is non-sticky and anti-sticky at normal temperature. After a certain price adjustment and hot pressing, fusion bonding and cross-linking and curing occur, and it becomes completely transparent. The cured EVA can withstand changes in the atmosphere and has elasticity. It will “top cover and underlay” the cell sheet, encapsulate it, and the upper protective material-glass, the lower protective material backplane (TPT, BBF, etc.), using vacuum Lamination technology is integrated. On the other hand, it can increase the light transmittance of the glass after sticking to the glass. It plays the role of anti-reflection and has a gain effect on the output of the solar panel.

Solar cells

The solar cell is the smallest unit of photoelectric conversion, and its size is generally 125 * 125 or 156 * 156. The working voltage of the solar cell is about 0.5V, which cannot be used alone as a power source. After the solar cells are packaged in series and parallel, they become solar panels, and their power is generally several watts to tens of watts, and one hundred watts to two hundred watts or more. They can be used alone as a power source.

Backplane

The back plate is the protective material on the back of the battery board. Generally there are TPT, BBF, DNP and so on. These protective materials have good resistance to environmental erosion, insulation and can be well bonded to EVA. The fluoroplastic film on the back cover of the solar cell is white, which reflects the sunlight, so it slightly improves the efficiency of the panel, and because of its high infrared emissivity, it can also reduce the operating temperature of the panel. Conducive to the efficiency of the battery board. Of course, the fluoroplastic film first has the basic requirements of aging resistance, corrosion resistance, and air tightness required for solar cell packaging.

Junction box

The junction box is generally made of ABS, and is added with anti-aging and anti-ultraviolet radiation agents, which can ensure that the battery version is not used for more than 25 years in the outdoor without aging and cracking. The terminal posts are made of highly conductive copper with nickel plating, which can ensure reliable electrical conduction and electrical connection. The junction box is bonded to the surface of the backplane with silicone.

Aluminum frame

The frame is made of hard aluminum alloy, and the thickness of the surface oxide layer is greater than 10 micrometers, which can ensure that it can be used in outdoor environment for more than 25 years without being corroded and durable.

Common specifications and power of solar panel components

1 ~ 200W Each time you increase the power, you can use 1W as the parameter. The following parameters can be used as a reference:

(1) Rated Power [Pmax] 10W; (2) Rated Power [Pmax] ± 5%; (3) Nominal Voltage 18V; (4) Design Life 25 years; (5) Production process

The first step of single-chip welding:

welding the battery cells to the interconnection strip (tin-coated copper tape) to prepare for the series connection of the battery cells.

The second step is tandem welding:

the cells are connected in series according to a certain number.

The third step of stacking:

continue the circuit connection of the battery string, and at the same time protect the battery sheet with glass, EVA film, and TPT back sheet.

The fourth step is lamination:

the battery sheet and glass, EVA film, TPT back sheet are bonded together under a certain temperature, pressure and vacuum conditions.

Step 5 Frame:

Protect the glass with aluminum frame, which is easy to install.

Step 6 Cleaning:

Ensure the appearance of the components.

The seventh step electrical performance test:

test the insulation performance and power generation of the component.

Performance parameters: electrical characteristics

(1) Temperature coefficient of short-circuit current: ± 0.05% ℃;

(2) Temperature coefficient of open circuit voltage: -0.33% ℃;

(3) Power temperature coefficient: -0.23% ℃;

(4) Temperature coefficient of working current: + 0.08% ℃;

(5) Temperature coefficient of working voltage: -0.33% ℃;

(6) Maximum system voltage: 1000V;

(7) Insulation coefficient: ≥100MOhm;

(8) Breakdown voltage: AC 2000V, DC 3000V;

(9) Wind resistance coefficient: 60m / s (200kg / sq.m);

(10) Compression resistance: 100Kg / ㎡;

(11) Impact resistance coefficient: able to withstand the impact of 227g steel balls falling from a height of 1m;

(12) Ambient temperature: ± 45 ° C;

(13) Good weather resistance: windproof and hailproof.

Power calculation

The solar AC power generation system is composed of a solar panel, a charging controller, an inverter, and a battery; a solar DC power generation system does not include an inverter. In order for the solar power generation system to provide sufficient power for the load, it is necessary to reasonably select each component according to the power of the consumer. The following uses the output power of 100W for 6 hours per day as an example to introduce the calculation method:

(1) First calculate the number of watt-hours consumed per day (including the loss of the inverter): If the inverter conversion efficiency is 90%, when the output power is 100W, the actual output power should be 100W / 90% = 111W; if it is used for 5 hours per day, the power consumption is 111W * 5 hours = 555Wh.

(2) Calculate solar panel: Calculate according to the effective daily sunshine time for 6 hours, and consider the charging efficiency and the loss during charging, the output power of the solar panel should be 555Wh / 6h / 70% = 130W. 70% of this is the actual power used by the solar panel during the charging process.

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