From A to D: Decoding the Grades of Solar Cells

By Kami Turky

Last Updated:

When we talk about green energy, knowing the different grades of solar cells matters. 

But, why? 

Because these grades tell us how good a solar panel is at turning sunlight into electricity. 

Take the top-notch Grade A cells, for example—they’re super efficient and last a long time, so you don’t have to replace them often. 

On the flip side, the lower grades, like Grade C or D, aren’t as fancy, but they are still good for simpler setups where you don’t need as much power. 

In this guide, I’ll walk you through what each grade of solar cell offers and how choosing the right type can fit your needs and help the environment.

Key Takeaways

  • Grade A solar cells are the highest quality available, free from defects like chips or cracks, which maximizes their efficiency in converting sunlight to electricity.
  • Grade B solar cells are cheaper and have minor imperfections that slightly reduce their efficiency with a filling factor ranging from 0.4 to 0.7.
  •  Grade C solar cells show visible defects and have significantly reduced efficiency, typically no more than 12%, and are often used in less critical applications.
  • Grade D solar cells are the lowest quality, composed of broken or flawed parts that are sometimes recycled into new silicon, used where high efficiency is not necessary.
  •  To assess the grade of solar panels, inspect the smoothness of the glass surface, the integrity of the cells, the evenness of silicone application, and the quality of the panel’s construction, including its frame and junction box.

What Do Grades in Solar Cells Indicate?

1. Grade A

Grade A solar cells are the best of the best in the world of solar panels. 

But what makes them stand out? 

Well, they’re pretty much perfect—no chips, cracks, or any other flaws that you might find in other cells. 

These little defects can mess with a cell’s ability to turn sunlight into electricity, so not having them means Grade A cells work at their best.

Now, looks matter too. 

Grade A cells look flawless.

They have this even color and crystal structure that makes all the pieces look identical. 

This isn’t just about looking good—it helps the whole solar panel work smoothly and evenly.

There’s this thing called the filling factor of the Current-Voltage Characteristics (CVC), which sounds complicated, but it’s just a way to measure how good a cell is at turning solar energy into electric power. 

For Grade A cells, this factor is over 0.7, which is a fancy way of saying they’re efficient.

These cells are also built to last

They don’t wear out quickly, which means they keep on delivering great performance for a long time. 

This makes them a smart pick for anyone looking for solar panels that are going to stick around and keep doing their job well.

Only the best manufacturers, the ones who know their stuff, use Grade A cells. 

These top-tier producers are all about quality and trust their reputation for using only the best materials. 

Their solar modules not only meet the standards expected of them but often surpass them. 

They even manage to work better in heat, which is a big deal for solar panels.

2. Grade B

Grade B solar cells are a step down from the top-notch Grade A, but they still have their place in the solar panel market. 

These cells have a few quirks—like uneven colors and a bit of a rough look with their crystal structures. 

Now, you might hear some people say these are just superficial issues and don’t mess with how the cells function.  

However, that’s not quite the full story.

The performance of Grade B cells is measured by their filling factor of the Current-Voltage Characteristics (CVC), which ranges from 0.4 to 0.7

This is lower than the over 0.7 rating for Grade A. 

What this means is that Grade B cells aren’t as efficient at converting sunlight into electricity. 

They do an alright job, but they don’t produce as much power as the Grade A cells.

Because of these imperfections, Grade B cells usually come with a lower price tag. 

This makes them an appealing option if you’re looking to save some money

But it’s important to keep in mind that you often get what you pay for. 

These cells might not perform as strongly, and they tend to wear out faster than Grade A cells. 

This could mean more maintenance or needing to replace them sooner than you’d like, which might erase any initial savings.

3. Grade C

Grade C solar cells are what you find when you go a couple of notches down the quality ladder from the top grades. 

These cells are kind of the underdogs in the solar world, showing visible defects and microcracks that take a toll on how well they perform. 

Typically, their energy production efficiency caps at about 12%

Because of these significant shortcomings, you won’t find any top-tier manufacturers using Grade C cells for their premium products.

These cells are noticeably flawed—microcracks can be seen with the naked eye, and it’s not uncommon to find broken pieces among them. 

Due to these defects, Grade C cells come at a much lower price point. 

However, this doesn’t necessarily make them a bargain, especially if you’re looking for something that lasts. 

Because of their reduced efficiency and durability, these cells are not chosen by reputable manufacturers. 

Instead, they tend to end up with third-tier producers or in DIY projects where high performance is not the priority.

Now, you might be wondering, “Where can these cells be used then?” 

Well, Grade C solar cells find their niche in less demanding applications.

 They’re often used in systems that require low voltage—like those designed to charge batteries with voltages of 12V, 24V, or 48V

This makes them suitable for small, off-grid setups where budget constraints are tighter and the highest efficiency isn’t crucial.

4. Grade D

Grade D solar cells are the leftovers in the solar world. 

They’re the bits and pieces that weren’t good enough to make the grade—literally. 

These are the cells that are either broken or have major flaws. 

Usually, they end up being recycled and turned back into new silicon because they’re just not up to snuff for making good-quality solar panels. 

But, believe it or not, they still end up being used, mostly by manufacturers who aren’t too picky about the quality of the modules they’re putting together.

So, what’s up with these Grade D cells? 

Well, they’ve got a lot of the same problems you’d find in Grade B cells—things like micro-cracks or other visual flaws. 

The big difference, though, is that Grade D cells are often not whole cells at all. 

They’re more like fragments of cells that once worked fine. 

These little pieces get patched together to form solar panels that are sold super cheap to folks who are trying to cut costs, or who have very minimal power needs.

Figuring out if a solar module is made from Grade D cells isn’t too hard. 

If you look at a panel and see it’s not made up of whole, intact cells, but rather bits and pieces stuck together, that’s a dead giveaway it’s Grade D. 

Especially if these modules don’t match up to the usual sizes like 125×125 mm or 156×156 mm—they’re probably made from scraps.

These kinds of panels are usually found in setups where there isn’t a huge demand for power—like small, off-grid projects that can get by on a little less juice. 

Sure, they’re cheaper, but the downside is that you’re looking at lower efficiency and reliability. 

So, Grade D cells are for when saving money is more important than getting top-notch performance.

How Can You Assess the Grade of Solar Panels?

1. Appearance Judgment

When you’re trying to figure out the grade of solar panels, a good look at several key parts can tell you a lot. 

Here’s a simple guide on what to check:

  • Surface Examination: Start by taking a close look at the glass on top of the panel. Feel for any rough spots or leftover bits of silicone. These little flaws can mess with how well the panel turns sunlight into electricity.
  • Cell Inspection: Next, check out the solar cells themselves. Look for chips on the edges or cracks that might be hiding. Sometimes, these damaged cells are still used, which can lead to safety issues and lower the panel’s effectiveness.
  • Back Quality: Flip the panel over and examine the back. It should be smooth and free from any bubbles or wrinkles. A clean and even back usually means it’s a quality panel.
  • Edge Assessment: Now, check the edges of the panel. They should be straight and flat. If they look like they’ve been manually altered or are uneven, this could mean the panel won’t hold up as well.
  • Silicone Evaluation: Take a look at the silicone seal around the back edge of the panel. It should be spread out evenly and fill the space between the panel and its frame. This helps keep the panel working well for a long time.
  • Welding Examination: Get a close look at how the solar cells are welded together. You shouldn’t see any signs of the welds breaking or leaking, and the cells should line up neatly. Good welding helps the panel work efficiently.
  • Junction Box Inspection: Lastly, check the junction box attached to the panel. Make sure its cover is secure and the wire lock works well and can be adjusted. A solid junction box is crucial for keeping the panel connected safely.

2. Purchasing Considerations

There’s another big factor to consider beyond just the specs: where and how you buy them. 

Let’s break this down into simpler terms and focus on what matters:

  • Authorized Dealer: It’s important to get your solar panels from authorized dealers of well-known manufacturers. Why? Because these dealers carry the real deal—top-notch, Grade-A panels. Plus, they back up their sales with strong after-sales support and extended warranties. Ensure to check all the paperwork like warranty contracts and invoices. 
  • Market Awareness: The solar panel market is booming, which is great, but it comes with a catch. Some smaller manufacturers might try to save money by recycling old solar cells into new panels. While this might sound eco-friendly, these cells often end up in lower-quality Grade B and C panels that just don’t hold up well—they can start failing in just a few years. On the flip side, choosing Grade A panels from reputable manufacturers means you’re investing in quality that’s built to last—at least 25 years.

Related article: How Long Does It Take For Solar Panels To Pay For Themselves?

Related article: Advantages And Disadvantages Of Solar Energy

FAQs

What Is Solar Grading?

Solar grading is the classification of solar panels based on the quality and efficiency of their solar cells, impacting their performance and longevity.

What Is the Difference Between A-Grade and B-Grade Solar Panels?

The difference between A-grade and B-grade solar panels lies primarily in quality; A-grade panels are flawless and highly efficient, while B-grade panels may show slight visual defects and offer reduced efficiency.

How to Check Solar Panel Grade?

To check solar panel grade, inspect the solar panel for visual defects, verify uniformity in cell appearance, and check documentation for the grade certification from the manufacturer.

How to Grade Solar Panels?

To grade solar panels, we assess factors like cell condition, efficiency metrics, and manufacturing consistency, typically performed by manufacturers or certified evaluators.

Conclusion

As promised, we’ve walked through the different grades of solar cells and how to pick the right one for your needs. 

Keep in mind, though, that Grade A cells are super efficient and last longer, but if you’re watching your budget, grades like B or C are still a good choice for simpler projects. 

Here’s a tip you might not have thought of: mix and match the grades. 

For example, use Grade A for the main parts of your setup and fill in with Grade B or C where the demands aren’t as high. 

Do you still have questions about how to apply this mix-and-match strategy, or need advice on where each grade might be best used in your specific setup? 

Feel free to reach out or leave a comment below.

Kami Turky

Kami is a solar engineer with nearly a decade of experience in researching, testing, and reviewing various solar products.He has also provided technical consultation to several organizations on the best ways to incorporate solar energy into their operations.When he’s not busy helping others find the best solar solutions, Kami enjoys spending time outdoors, hiking, camping, and exploring the natural wonders of his home state.

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