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5th October, 2023Story of an innovative company: Sunpower
Sunpower panels are often touted as the best solar panels in the world – but are they really? In this review, I will first briefly introduce the company and the panel. Next, I'll highlight eight potential problems with traditional panels. After that, I'll show how SunPower solved these eight problems by building a fundamentally different panel. Following this, I will provide my thoughts on SunPower's financial situation - is SunPower a risky option in today's volatile panel manufacturing climate?
The California-based solar panel company was founded in 1985 by Dr. Richard Swanson. With a record efficiency of 21 percent, SunPower has been hailed as the world's most durable panel, with the lowest degradation, the longest warranty by far, and an unprecedented expected lifespan of 40 years. No wonder SunPower has been used in some of the most interesting projects on earth.
Sunpower's panels are frequently described among the world's elite solar panels. But do they really keep their promises? In this analysis, I will first discuss the genesis of the brand and the characteristics of its products. I will then discuss the challenges faced by conventional panels and the innovative way SunPower has responded to them. I'll conclude with a reflection on SunPower's financial stability in the fluctuating landscape of solar panel manufacturers.
Founded in California in 1985 by Dr. Richard Swanson, SunPower has distinguished itself with a record efficiency rate reaching 21%. Their reputation is built on the robustness of their products, their resistance to degradation, an exceptionally long warranty and an estimated lifespan of 40 years. It is therefore not surprising to see them associated with innovative projects around the world.
The design of traditional solar panels:
Today, a typical solar panel is assembled from about 60 silicone modules, called “cells.” Each of these cells is marked horizontally with a thin layer of silver and is connected vertically by silver strips.
The montage is then framed like a work of art; these cells are preserved thanks to an EVA/polymer layer (similar to a plastic sheet), with a window on the front and a protective layer on the back. Everything is consolidated in an aluminum frame.
When sunlight hits the silicone cell, electricity is produced, passing through the screen-printed silver, along the bonding strips, to reach a junction box attached to the back of the panel. These panels interconnect using MC4 connectors.
The assembly formed by the silicone cell, the bands, the glass, the polymer material, the protective layer, the frame, the connection box, and the MC4 connections is what we call the “List of Components » or BOM;
Cheap solar panels vs Sunpower?
Obviously, producing a panel requires the use of a list of premium materials, using recent and well-maintained automated equipment. When we think of high-end solar panels, we immediately think of brands like SunPower, LG and Winaico. Others, like Canadian Solar, JA Solar and Phono, represent Chinese quality at a more attractive cost. However, among the multitude of panels available, one in particular surpasses all the others.
Why are Sunpower panels the best?
Fragile Cell vs Sunpower Cell!
Sometimes, during a meeting with a customer, I show a classic solar cell and explain how it works. Curious, they often pick it up, and within seconds it breaks. Their surprise is palpable, but I continue to feign amazement to accentuate the effect. Then, I highlight the delicate nature of conventional solar cells.
Solar panels require delicate handling. Common errors, such as improper handling or transportation, can cause micro-cracks. In addition, with technological developments and the search for cost reduction, panel components are becoming thinner and thinner, accentuating the risk. Although this risk is present even with higher quality panels, there are exceptions.
This is the case with SunPower. After the fragility demonstration, I often show a SunPower cell. The latter, reinforced by a copper base, is much more robust. By combining this robustness with the quality of the SunPower glass and frame, these cells are virtually immune to micro-cracks, even in real-world use conditions. »
Exceptional reliability:
Invest with confidence, knowing the quality of SunPower Maxeon panels is proven. In real-world field testing over 8 years and with 800 panels across 000 sites, SunPower Maxeon solar panels demonstrated the lowest degradation rates in the industry,264 representing nearly 1 times greater reliability. to her conventional panels (see PVEL 2023 test).
Tolerance and impact of shading on the Maxeon cell:
SunPower panels offer better performance in partial shading. Here is a brief explanation:
A conventional silicone cell has the positive pole on one side and the negative on the other. Because of this large electrical separation, when the cell is shaded, it generates a relatively high reverse voltage to overcome resistance. Generally, this voltage varies between 15V and 20V for a standard cell. This high voltage can cause harmful hot spots and reduce panel efficiency. If this reverse voltage becomes too high, the bypass diode, designed to protect the panel, activates. Each time one of these diodes activates, the panel's production decreases by a third. And these diodes have a limited lifespan: the more they are used, the more quickly they risk failing.
SunPower, with its Maxeon cell, has placed the two poles, positive and negative, on the back of the cell, very close to each other. So, in case of shading, the reverse voltage is only 2,5 volts (X series) or 5,5 volts (E series). The advantages of this design in shading conditions are multiple:
- The reverse voltage is reduced.
- Less heat is generated.
- More current and energy are produced.
- Bypass diodes are used less often, thus increasing their lifespan.
Do the panels have bypass diodes?
Contrary to popular belief, SunPower panels do have bypass diodes. Even though a SunPower video claims that every cell has one, that is not the case. These diodes are installed for each third of the panel. Does this mean that with SunPower panels we don't need optimizers on a shaded roof? Not quite. Under heavy shading conditions, current imbalance may still occur. However, this effect is much less marked than with a traditional panel. Optimization can therefore still be beneficial, particularly with solutions like Tigo TS4 or SolarEdge. This optimization also offers advantages such as individual panel monitoring and increased safety in the event of fire. For more information on optimizers, you can refer to the first part of this article.
Induced Degradation (“LID”)
In order to enable silicon cells to generate electricity, they undergo a “doping” process. The majority of solar panels are doped with phosphorus and boron, resulting in P-type silicon. However, this type of silicon has a weakness: it is susceptible to “light-induced degradation” or LID. This widely documented phenomenon reduces the performance of standard panels by 1 to 4% after just a few hours of exposure to light.
As for SunPower panels (and certain LG models), they use type N silicon. The latter is significantly superior in terms of performance and does not have the disadvantages of LID. And of course, it should not be confused with LSD.
Impact of temperatures on the lifespan of solar cells?
The traditional panel manufacturing process requires a very delicate method of connecting the cells together using thin ribbons. If this is done correctly, there will be enough clearance to allow for expansion and contraction due to daily temperature variations. However, even if this step is carried out correctly, this connection system remains the weak point of the panel.
SunPower panels, on the other hand, use strong, flexible copper connections, designed to accommodate changes in size.
Tolerance to extreme heat and severe climatic conditions:
Sunpower solar panels prefer cool, sunny days, not hot days like many people think. As their temperature increases, their efficiency decreases. The technical sheets for each module mention this trait under the name “thermal coefficient”. SunPower's Maxeon cells, with their copper base, actively dissipate heat, allowing the panels to better withstand high temperatures. As a result, they have a lower thermal coefficient, ensuring optimal performance even on scorching days.
High humidity can corrode solar panels. Moisture seeps into the back coating of conventional panels over time, causing corrosion of silver circuits and reducing their performance. Although this corrosion appears more slowly on high quality panels, signs of corrosion can be observed after 10 to 20 years. Studies show that hot and humid conditions reduce the performance of standard panels after just 2000 hours of exposure.
Back-contact IBC type cells:
Traditional cells use fine silver prints and thin ribbons to transfer energy from the silicon to the junction box. The major disadvantage of this design is that these elements cast a shadow on the cell, reducing its efficiency. It is obvious that putting an obstacle to light in front of a solar cell is not ideal. This brings us to the next point: roof installation limits.
In conclusion, are Sunpower panels the best on the market?
SunPower designs one of the most advanced solar panels on the market. Their cellular technology is less vulnerable to micro-cracks during the transport and installation stages and in the face of climatic hazards. These panels are more efficient in shaded conditions, better manage temperature variations and offer optimized production during heat peaks. They also have better resistance to humidity compared to many other models. In addition, their high efficiency allows optimal installation even on roofs with limited space. Although SunPower is currently experiencing financial challenges, many solar panel manufacturers are experiencing similar situations. By choosing SunPower, you are investing in cutting-edge technology, even if, in the worst-case scenario, the company faces insurmountable obstacles in the future.