Ask Solar Mango

Solar panels are the heart of a solar power system as they are the ones that generate electricity! The rest of the solar power plant is only to ensure that the electricity thus generated is converted and transported optimally.

In addition to its fundamental role, solar panels account for around 60% of the total cost of a solar power system.

The above two aspects – its critical role and its significant contribution to the cost – makes the selection of solar panels an important decision from operational & economic viewpoints.

This makes it imperative to put in sufficient time and effort in choosing solar panels.

What are metrics for comparing solar panels?

From our understanding of the market there seems to be 2 criteria based on which the quality of panels are evaluated.

1. Tier Classification – Tier 1, 2, 3

Today, we see that many module manufacturers label themselves as ‘Tier 1’manufacturers. But the odd part is that many of these so-called tier 1 manufacturers are not provided with that status by a standards body. So there is no clear definition on which panels belong to this category and why they belong to it.

But, the generally accepted characteristics of a tier 1 manufacturer are the following:

• Uses the best grade of silicon to produce solar cells (higher the silicon grade, the longer the solar cell will last and the better it will perform)
• Produces some of the best performing solar panels at reasonable price.
• Is vertically integrated, meaning they make their own cells and wafers
• Controls each stage of the manufacturing process with advanced robotic processes
• Invests heavily in R&D.
• Produces 1 GW of solar panels in a year

It is worthwhile to note that Bloomberg New Energy Finance, due to the demand for categorizing tier 1 players, has come up their own list of tier 1 manufacturers based on their bankability. This list could be referred, to get an idea of the major Tier 1 manufacturers.

Tier 2 and Tier 3 manufacturers should be lower in selection priority compared to Tier 1 manufacturers. Refer the following blog post to understand more on tiering of modules:

http://www.solarmango.com/blog/2015/11/07/what-are-tier-1-tier-2-and-tier-3-solar-panels/

2. Grading – Grade A,B,C,D

This is another method for classifying solar panels. Solar panel grading is defined more clearly and is based on the types and degrees of some of the below defects.

• Scratches on the frame and/or glass
• Excessive or uneven glue marks on glass or frame
• Gap between frame and glass due to poor sealing
• Always lower output than stated in data sheet.

Essentially, grade A panels are the best of the lot and it is advised to go for them.

For a more detailed explanation, please refer the below link on solar panel grading:

http://www.solarmango.com/blog/2015/11/06/what-are-the-different-grades-of-solar-panels/

Other Aspects to be Considered

• Temperature Effect – Temperature effect on solar panel performance also needs to be considered, as the efficiency of solar panels drop with increase in temperatures. You hence need to choose solar panels with low temperature coefficients, which imply that the efficiency decrease will be lower with increase in temperatures (beyond 25 degrees C)
• Flash Test Reports for Panels – you might want to do a flash test on a random set of solar (more on flash tests here)
  Anti-reflective coating on panel glass – having this type of coating ensures that less light is reflected from the panels and thus more light enters it and gets converted to electricity
• Performance Guarantee – Panel makers can give you either a fixed performance guarantee or a linear performance guarantee. A linear performance guarantee will give you better electricity output overall

General Recommendations

• Generally, it has been agreed that Tier 1 panels are of high quality. And, it can be said that if you choose a grade A or Grade B panel, you are safe. Therefore, the most obvious recommendation would be to go with Grade A+ Tier 1 modules. Kindly note that this combination could be more expensive, so you might also want to look at Tier 1 & Grade B or Tier 2 & Grade A combinations as well. Between the Tier and the Grade, the Grade is more important – just ensure that you do not purchase panels that are below B.
• Another recommendation is to follow this up with a thorough analysis of the Bill of Materials (BOM) to ensure that the quality of the glass, frame, backsheet etc., is maintained. The integrity of these sub-components is a deciding factor in ensuring the efficient long-term functioning of panels. The key sub-components to keep in mind are:
  • Cell
  • Glass
  • Backsheet

Need assistance in panel selection for your solar power plant?

Please send a note to Mr. Nikhil.

Email: nikhil@solarmango.com

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