Note: This article focuses on crystalline silicon (c-Si) solar panels – the most common type of cells used in the market.
Does The Solar Panel Size Matter?
The use of solar systems had gained a lot of popularity over the last three decades. We witness improvements in technology that have led to an increase in the power a panel can produce. Surprisingly in this period, solar panel size hasn’t increased all that much. The energetical gain of a single Photo Voltaic cell increased 7x which leads to greater power output. The size of each solar module making a system could be a key element to scale projects.
The following parametermine the power gain of a single panel:
- Solar panels are just collections of Photo Voltaic cells
- How many independent cells the panel contains
- The efficiency of those cells
- The dimensions (physical size) of a solar panel are an outcome of:
- the amount of Photo Voltaic cells the panel is made of,
- The size of the silicon wafers ( which are the fundamental materials used for the generation of those cells)
- The density o cells used in the panel
Popular Sizes For Solar Panels Are S, M, L, AND XL
Before we dive into the specifics, let’s set some common ground. There isn’t a formal definition of what makes a solar module a part of any size group. We’ll consider an Extra Large solar panel from a commercial shipping standpoint. A package over 8 feet is typically subject to an over-size surcharge. Our minimal threshold for XL is going to be this size. Remember we are talking about shipping, the measure is the size of an item including the packaging. As a rule of thumb usually, panels consisting of over 72 cells reach those measures.
An additional categorization we’ll do is to think about earlier designs of solar panels which are made of 36 cells as Small. The 60- and 72-cell panel modules, which are very popular in the industry for the last ten years will be considered Medium and Large respectively.
There are exceptions some exceptions to this categorization keep in mind that:
- Today a new technological method is using half-cut cells power losses. Often the latest are marketed as having 120 or 144 cells, although still having the output capacity of 60- or 72-cell modules respectively. We will fit them into our Medium or Large dimension groups.
- Surprisingly a different cell arrangement of 96-cell panels will not be longer than our criteria although they have a bigger surface area. This happens because of cell-matrix arrangements of 12×8 resulting in them not being longer than 72-cell panels, just wider.
- With new developments of larger wafers such as the M6, 72-cell panels utilizing it or larger wafers would be physically bigger than the 8 feet criteria and therefore categorized as XL solar panels.
Some Noteslimitations XL Size Solar Panels
Choosing XL solar panels has some limitations either for the installer or for you if you plan to do it on your own. f Although not widely used in systems yet XL panels are an upcoming trend. So what should you consider?
- The panels are too big for a single installer to carry around or even install on his own. Consider asking someone to help you before starting installation.
- It is impossible to fit them in a 7′ truck bed and close the tailgate, maybe consider renting a bigger truck.
- As widely discussed before those panels are subject to extra shipping charges consider it when planning your system.
- The experienced installer of M and L panels should consider the extra weight of XL panels may require a different racking.
Why are solar panels growing all of the sudden?
PhotoVoltaic cells’ efficiency has improved gradually over the last three decades. In the mid-’90s, a panel efficiency of 15% was state of the art for cell technology. Currently, we managed to reach an efficiency of 29% in laboratory conditions. The current standard for modern commercially available modules is in the low 20s range. We expect to see an increase in efficiency due to the latest technical improvements in the coming years.
The next efficiency technological barrier we are facing is the theoretical limit of single-junction c-Si based cells which is around 30% (AKA Shockley-Queisser limit).
Raw silicon is melted and shaped into long ingots, which are then sliced into paper-thin wafers that form the backbone of solar PV cells.
Cell efficiency R&D is working on many aspects of the panels, from testing new materials to different geometrical shapes for the array. An interesting one of them is related to the physical size of the cell- the silicon wafer that cells are built around. Earlier panel designs were made of wafers approx 100mm square. Whereas in the mid-’90s, 125x125mm wafers became the new standard. Those were eventually replaced by 156x156mm wafers (which were known as an “M0” wafer, which started the current naming convention for silicon wafers. Currently the wafers extend to 217×217 mm wafers also known as “M12+”).
Alongside the increase in solar cell efficiency (and size), the number of cells in an array has also increased. 36-cell arrays were the first to be the standard size. The latest are commonly used as 12V “off-grid” panels. Later on, the 60-cell arrays became the standard and are still being manufactured today. Nowadays the 72-cell arrays are developing toward becoming an additional standard. The 72-cell modules are also favored by commercial and utility-scale projects.
With our society’s ever-increasing demand for electricity, incremental improvements in solar cell power production, and the need for sustainable sources of energy solar systems of all sizes become more commonly used. Similar to any market this is good news for consumers as it can pushes system costs down and make them more affordable. As long as you carefully consider labor and shipping costs when purchasing extra large solar panels there could be a real alternative for all scales of systems.
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