HOW TO SOLDER SOLAR CELLS TO BUILD A RESPECTABLE LOW-COST PHOTOVOLTAIC PANEL
L'uso dell'energia solare non è stato sviluppato perché l'industria petrolifera non possiede il sole.
Ralph Nader
A bit of information that I hope will be useful for you to build a photovoltaic panel:
Photovoltaics is a technology that allows the direct conversion of sunlight into electrical energy, utilizing the so-called photovoltaic effect.
This effect is based on the property that certain appropriately treated semiconductor materials (including silicon, an element widely found in nature) have to directly generate electrical energy when struck by solar radiation, without the use of any fuel.
The most basic device capable of performing such conversion is the photovoltaic cell, which can produce about 1 to 1.5 Watts of power when exposed to a radiation of 1000 W/m² (standard irradiation conditions).
A solar cell, also known as a photovoltaic cell, is a device that converts light energy into electrical energy.
Sometimes the term solar cell is used to refer to devices that capture solar energy, while the term photovoltaic cell is used when the light source is of unspecified nature.
The solar cell, used to produce energy, has an efficiency between 13% and 22%.
Usually, the cells, made from semiconductor material like silicon, which is widely used in this field, are 0.25 mm thick and have a square shape of 125 x 125 mm (5"x5") or 156 x 156 mm (6"x6").
OPERATION
When the cell is exposed to light, if impurities are introduced into the crystalline structure of silicon, used for the construction of solar cells, an electric field is created which is then converted into energy.
Photovoltaic conversion is a physical phenomenon that allows the direct transformation of light energy into electrical energy in elementary structures, the photovoltaic cells.
These devices are made from semiconductor materials, which means materials that conduct electric current and whose resistivity decreases as the temperature increases and due to the presence of impurities.
The photovoltaic effect consists of the generation of an electrical potential difference, thanks to the integration of a flow of radiant energy with matter.
In our photovoltaic kits, which you can find in the specific category of the website, You find two types of welding wire, the TAB wire and the BUS wire. You can easily recognize them because the first one is thinner and is used to solder the cells together to form strings, while the BUS wire is used to connect the strings of cells together.
Another essential component of the KIT is the flux or rosin flux, which is used to enable proper soldering. For soldering, we recommend using a 60W/80W flat-tipped soldering iron, similar to a split screwdriver (it's very economical, costing around €10.00), and we suggest placing the cells on a smooth glass surface or other thermally insulating materials.
In the KITS, we do not provide the glass and the framework because they are easily obtainable from glassmakers or DIY stores, to avoid increasing the shipping costs which would then impact your final savings.
The solar cell, as you can see in the photo below, has the negative pole on the front side, the blue-colored one to be precise, while the positive pole is on the back side. The strips you see in the middle are called connection bands or bus bars and are used to connect the cells to each other.
Given that each solar cell has a voltage of 0.55V (0.6V Peak), to build a panel that charges a 12V battery, you will need at least 30 cells that you will have to connect in series (the positive pole of one cell goes with the negative of another) to obtain an adequate voltage. To build a solar panel, the first thing you need to take care of is the soldering of the solar cells, in a "serpentine" type layout which I provide below, where we have 3 strings of 6 solar cells connected in series. Thus, considering 0.55V per cell, you will have a photovoltaic panel with a voltage of about 10V at a current of 3.8A, for example. consideration of the solar cell 3"X6" inches (76X156 mm) 3BB (3 busbars)From:
Below we provide some sample data on the voltage-current characteristic curve measurements. of a solar cell sold in our store; we thank Prof. Alessio Piana and his team for sharing this magnificent work with us.
Circuit Diagrams
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Here below, instead, another laboratory test on an already assembled solar panel composed of the 36-cell solar kit 1"x3" inches available in our online store
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It will be very important to mount solar cells effectively to ensure the long lifespan of the panel, low risk of corrosion, and breakage. There are several options to achieve a good result, such as encapsulating the cells within a double-glazed window or using special silicone resins like QSIL 216 or Ethylene Vinyl Acetate (EVA) sheets available in our store .
In the category "Your Projects" on the siteYou can also find other more economical methods that some of our clients have used to achieve a good result, in particular You can refer to the article written by Alessandro Paglialonga.