# What is an example of the structural design of a photovoltaic module?

What is an example of the structural design of a photovoltaic module?
Taking the design of a polysilicon battery module as an example, the technical parameters required by the module are set as: maximum power Pmax=275W, open circuit voltage VOC=38.0v, and filling factor FF=77%.

The first step: select the appropriate gear and quantity of solar cells according to the parameters required by the module. The output voltage of the crystalline silicon battery varies little with the battery area. For a 156mm×156mm or 125mm×125mm battery, the open circuit voltage is basically 0.6~0.65V. Even if the 156mm×156mm battery is cut into any size, the open circuit voltage output It is also about 0.6~0.65V, so when designing, it can be assumed that the output open circuit voltage of any size battery is 0.62V, and Vmpp is generally assumed to be 0.5V.

First, determine the number of batteries according to the voltage required by the module. Calculate the number of batteries for the module: 38V/0.62V-61.3 pieces, generally rounded according to the empirical value, and choose 60 pieces; then calculate each piece of battery according to the power required by the module and the number of batteries The required power, the power of a single cell is about 275W/60=4.58W; then the maximum power Pmax of the battery, the open circuit voltage VOC, and the filling factor FF of the component are substituted into the formula FF=Pmax/(VOC×ISC), and the short-circuit current is calculated. ISC=9.39A; Finally, determine the efficiency and gear of the required solar cell according to the above parameters. Usually, there will be some losses when the battery is packaged into a module. This loss is called Cell to Module (CTM) in the industry. Generally, the value is 98%~100%. Usually, the polycrystalline battery is 1.5% higher than the monocrystalline battery. If a special packaging material is used to increase the absorption of light by the solar cell, the output current of the module can be greatly increased, thereby increasing the output power of the module. At this time, the CTM may exceed 100%. In this example, assuming that the CTM of the module is 99%, then The required battery power is about 4.58w/0.99-4.63w, then the battery efficiency is: [4.63w/(0.15675 × 0.15675)m²]/1000 W/m²=18.8%, so choose the efficiency in the 18.8%~19.0% range bit battery.

Various batteries will have certain differences due to different process conditions.

Now the industry has basically used 156.75mm × 156.75mm silicon wafers, so if the power of this size battery needs to be calculated 156mm × 156mm, it can be calculated according to the area.

Step 2: Design component size and structure according to battery size, quantity and related electrical requirements. Generally, 3 diodes are selected for the assembly of components, 60 cells are designed into 6 strings, each string is 10 cells, and each diode is connected in parallel with two strings of cells. After the structure is determined, the distance between each component inside the module can be determined first according to the electrical requirements. Usually, the distance between each cell is 3mm, the width of the busbar is 6mm, the busbar is 3mm away from the battery, and the distance between the busbars is also 3mm. The distance between the strip and the edge of the glass is 14.5mm (it may be reduced to 12mm after accounting for the tolerance of the production process, which can also meet the IEC distance requirements), the gap between the battery strings is 4mm, and the distance between the edge of the battery and the edge of the glass is also 14.5mm . According to the above parameters, the required glass length is 156×10+3×9+3×(6+3)+14.5×2=1643(mm), and the glass width is 156×6+5×
4+14.5×2=985 (mm), the glass thickness is generally 3.2mm, so the final size of the glass is 1643mm×985mm×3.2mm.

Step 3: Design the aluminum frame according to the component size (mainly determined by the glass size). Generally, the wall thickness of the aluminum frame is 2mm, and the height is 35mm. Considering the gap between the frame and the glass edge (used to fill the silica gel), it is 1~1.5mm. Therefore, the outer dimension of the aluminum frame is based on the glass size. The length and width are increased by 7mm, so The overall size of the module is 1650mm×992mm×35mm, and the design of the crystalline silicon photovoltaic module is completed.

The crystalline silicon photovoltaic modules on this website have the following three main design schemes:
(1) 156mm×156mm polycrystalline silicon cells are used, which are composed of 6 columns and 12 rows of 72 cells in series. The module power is 315~345W, which is referred to as 72 polycrystalline silicon modules later;
(2) 156mm×156mm polycrystalline silicon cells are used, which are composed of 60 cells in 6 columns and 10 rows in series. The module power is 265~290W, which is referred to as 60 polycrystalline silicon modules in the following;
(3) 125mm×125mm monocrystalline silicon cells are used, which consist of 6 columns and 12 rows of 72 cells connected in series. The module power is 195~215W, which is referred to as 72 monocrystalline silicon modules (this type of modules is fading out of the market).

In fact, with the development of technology and the diversification of the market and changes in individual needs, various types of component products have also emerged as the times require. For the structure and design of special components, you can refer to the above design scheme.