How Solar Panels Are Made

Written by Tony Chang

June 5, 2023

How Solar Panels Are Made

Solar panels have a life expectancy of more than 25 years. Every fault or inconsistency in manufacturing solar panels will be magnified over the long, 25-year service life.

It is important to choose high-quality solar panel brands, like WINAICO, to make sure the modules can withstand the stresses from the environment throughout 25 years.

We share the secrets behind making high performance and reliable solar panels the WINAICO way, so you can distinguish the best solar modules from the rest.

Quality Solar Panel Production Starts With Reinforced Glass

At the beginning of the solar panel production line, a piece of reinforced glass is loaded onto the conveyor belt by the robot.

The reinforced glass has been chosen by WINAICO to withstand the impact of 35 mm hailstones at 100 km/h, so the solar panels can survive heavy snow and hailstorms.

solar glass
A piece of reinforced glass is placed on the conveyor belt. Not only does the glass need to be tough and resilient to withstand the weather, but a layer of Anti-Reflective Coating on the surface also reduces the amount of light reflected by the glass. This has the effect of increasing the sunlight absorbed by the glass by 3%.

Two Layers of EVA to Glue Every Component Together

Two sheets of ethylene-vinyl acetate (EVA) are required to glue the solar panel components today. One sheet is placed on top of the glass, the other one is placed over the solar cells after the stringer and layup stage.

solar panel EVA
A sheet of EVA is placed on top of the glass. WINAICO solar panels only use EVAs that are resistant to UV and waterproof. This way, the EVA layer will not turn yellow after prolonged exposure to the sun, and thus not reduce the amount of light absorbed by solar cells.

Solar Cell Halves Are Soldered With Multiple Wires Before Laid up Into Strings

Since WINAICO released the GEMINI product series, half cells have replaced full solar cells as the basis for solar cell strings.

A half-cell layout has the advantage of reducing the currents inside the solar panel by half to reduce internal conduction losses to increase module efficiency. Our solar cells also use multi busbar designs to further lower internal resistance for a power boost.

auto layup solar cells
A robot arm lines up the soldered half-cell strings into a panel layout. Once the solar cells are soldered into long strings, a robot arm lays up the strings into a solar panel layout, ready to be covered with a second layer of EVA.

A Waterproof Backsheet Completes the Laminate

A layer of backsheet goes on the back side of the solar panel to provide a waterproof cover.

solar panel backsheet
A roll of backsheet is sliced to fit the solar panel.

A top quality backsheet can withstand the stress of long term exposure to UV radiation without cracking. This waterproof layer allows solar cells to dissipate heat to maintain top performance without being damaged by moisture and condensation.

The EL Stage Before Lamination Screens Out the Cell Cracks and Poor Solder Joints

Electroluminescence (EL) works like the X-ray for solar panels, by imaging the conductivity of solar cells. By introducing a small electric current into the solar panel, the conductivity of the solar cells is directly proportional to the brightness of the image.

pre EL solar module
EL stage can screen out solar cell cracks before laminating the solar panel.

Therefore, any solar cell defects, such as microcracks, or poor solder joints, would appear on the image as dark, high resistance areas. This way, we can make sure no cracked and poorly soldered solar cells go into the laminator next.

The Laminator Fuses the Layers Into a Waterproof Solar Panel

The laminator is a temperature-controlled oven that heats up to melt the backsheet and EVA to form a waterproof laminate around the solar cells and glass.

lamination solar panel
The waterproof laminate that protects the solar cells. Then the laminate is slowly cooled in a controlled manner to allow the layers to fuse into a strong bond. A good laminate should have the backsheet and EVA melt around the edge of the glass to make sure the solar panel edges are as watertight as everywhere else.

Visual Inspection Stage Screens Out Production Defects

Cell string alignment, wire alignment, uneven solar cell gaps are examples of defects that rarely happen in production, but still need to be screened out.

So we use a robot arm that flips the solar panel laminate up for our Quality team to visually inspect the panel under the light.

solar panel visual inspection
A visual inspection to screen out production mistakes.

If our team finds any misaligned solar cells or wires, we would downgrade the solar panel and take it off the production line.

A Potted Junction Box Can Protect Solar Panels From Leakage Currents

The junction box on the back of the solar panel functions as the contacts to deliver DC currents out of the panel.

If dust or water build-up within the junction box, leakage currents can arc or cause a fire.

potted solar junction box
Potting a junction box.

We use potted, IP68 junction boxes to make sure no dust or water can trickle into the enclosure to short circuit the panel.

Aluminium Frames and Double-Sided Insulation Tape Make Solar Panels Strong and Reliable

Unlike most other solar panel brands that use silicone gel, WINAICO only uses double-sided tape to insulate the laminate during framing.

Silicone gel is notoriously unreliable as long term insulation, as the gel would stiffen and lose adhesion with frame and glass after a few years.

As a result, solar panels framed with silicone gel would deteriorate in both dry and wet insulation resistance soon after installation.

WINAICO uses double-sided tapes to insulate the solar panel edges before using the framing machine to complete the solar frames.

solar framing machine
Frames are loaded onto a framing machine.

The double-sided tape’s reliability means our solar panel frames remain intact even after suffering rain, snow and wind, year after year.

Solar Panels Are Thoroughly Cleaned Before a Final EL Stage and Flash Test

A cleaning process using isopropyl alcohol makes sure no tape or any chemical residue is left on the solar panel.

solar panel cleaning
IPA is used to thoroughly clean a solar panel.

Then a solar panel needs to pass through EL one final time to make sure only perfect solar panels are shipped to our customers.

Finally, a solar panel is flash tested to confirm the output power is correct for shipping.

Our Unique Solar Panel Packaging Protects Our Panels Through Worldwide Delivery

Once our solar panels are ready to be packaged, they are vertically placed in our unique solar package.

Our panel boxes are known to withstand around a ton of weight while empty, so our customers can rest assured that we don’t exert excess weight on panels when stacking pallets.

This way, no microcracks appear on our solar panels during transport, allowing our customers to receive perfect WINAICO solar panels every time.

To learn more about how WINAICO solar technologies can help with your rooftop energy production, please get in touch with us.










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