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Choosing a PV Solar Module

Cost is not the most important thing when considering a solar panel. Perhaps the greatest consideration is to remember that you will be living with your decision for a very long time – upwards of 30+ years.

There are many different kinds of solar panels on the market today to fit any size roof, recreational vehicle, boat, etc. Recently released from TESLA are solar roof shingles boasting higher efficiencies and durability than standard PV (photovoltaic) solar modules.

There are even foldable and rollable panels for traveling. What you are ultimately searching for is the best efficiencies, power, durability and warranty for the best price.

For these examples we will focus our design to a standard home or business. As with most solar components – it is true that not all solar panels are the same. Below are the top 6 most important things to consider when choosing your solar panel.

#1: Polycrystalline vs Monocrystalline

The two main types of PV modules available on the market today are polycrystalline and monocrystalline solar panels. These terms refer to the silicone cell that makes up the solar panel.

A monocrystalline cell is a pure silicone cell and a polycrystalline cell is made of many “flakes” of melted silicone pressed together. Monocrystalline panels are often more efficient and can produce more power than an equally sized (physical size) polycrystalline PV module. This is due to the purity of the silicone in the solar cell.

Because monocrystalline panels are made of pure silicone they cost a good bit more than a polycrystalline panels and also waste more raw silicone in the process when compared to polycrystalline panels.

A notable benefit of monocrystalline over polycrystalline is the panels high production performance in low-light and cloudy conditions. Because of this difference in price, many homeowners who have the available roof space will choose a top-tier polycrystalline panel over a monocrystalline panel to save money on the solar installation.

#2: “A” Grade and “B” Grade Panels

There are actually 4 different “grades” of solar cells on the market but finding anything worse than a B grade solar cell nowadays is quite rare with the onset of the “solar boom” and refined manufacturing processes.

The simple recommendation is to always go for an A grade solar panel. The difference between an A and B grade solar panel may not be very noticeable but will make a difference in the long run.

An A grade solar panel will have no real discoloration, no scratches or dents and will have been tested with proper electronic cell testing equipment to measure efficiencies. With the price of PV modules plummeting there is no need to sacrifice quality and get anything less than a “top-tier” A grade solar panel.

#3:  Tolerance and rated power

Solar panels come with a “tolerance” rating which means the panel with either be below, meet or exceed its “nameplate” rating. For example – a mid-range panel that comes from a company not well known may say that it produces 300 watts but really only can put out 290 watts under standard test conditions (STC).

This is shown on your panels specification sheet and on the panel itself as a -%/+% number. A mid-grade panel may show a -3%/+3% tolerance. This means it will either produce 3% less than the name plate wattage due to production issues but also has the ability, under ideal conditions, to produce 3% over the nameplate wattage.

A top-tier Grade A panel such as Trina Solar’s PD14 polycrystalline module has a tolerance of -0%/+3% which means the panel will only produce more than the rated wattage. This is the tolerance, or efficiency rating, you want to look for.

#4: General Construction

Most solar panels come with a sort of “topographical” glass that covers the solar cells. This angled glass absorbs light rather than reflecting it, increasing the production of your panel. The main difference is in the quality and thickness of the glass.

If you live in Maine or in a hurricane-prone region you are going to want a panel with at least 4.0mm thick glass that can take 2” hail falling at terminal velocity without the panel breaking. The same can be said about coconuts and avocadoes for those of you living in more tropical regions.

Consider purchasing a panel not made by hand but by a computerized manufacturing system so there are no future issues with the seal of the frame on the corners, the glass and it’s contact with the frame and the overall quality of the glass itself.

#5: Reviews and Working Experience

The industry standard warranty for a mono or polycrystalline solar panel is a 10 year warranty that the panel will produce at least 90% of the original wattage when it was new and a 25 year warranty that the panel will still be producing at least 85% of its original output after the 25 year period. There are many companies that have better warranties, such as a 25 year warranty that the panel will produce at least 90% of its original power output (such as Germany’s MAGE brand panels).

The best advice is to ask yourself – How long has this panel manufacturer been in the industry? Are there good or bad reviews of the panels from people who have them installed? Does this company spend any money on research and development? And what value does a 10 or 25 year warranty have when purchasing a panel from a manufacturer that has only been in the industry producing solar panels for 5 years?

#6: As always.. QUALITY QUALITY QUALITY!

Go with a top-tier, grade A solar panel. Recommended solar brands that have decades in the business, megawatt plants around the world, spend money re-investing in the company on research and development and keep up with new technological trends and quality control standards include (but are not limited to):

This is not the definitive list of the best but represents some of the premier manufacturers in the market. When searching for a solar panel perhaps use some of these manufacturer’s models to compare with other panels on the market that you may be considering for your project.

Using these top-tier companies’ specifications as a benchmark can only help point you in the right direction when choosing a panel that will be providing you power for 30 years or more.

Need help with selecting the right equipment for your solar project? Request a free solar consultation by clicking on the button below.

Please continue reading to find out how to choose your other solar components and which type of system is best for your particular use.


Kyle Johnston
This post was written by: Kyle Johnston 

Originally from Easton PA, Kyle Johnston is a solar installer and owns and operates 
Lux Aeterna Solar Energy in Antigua, Guatemala. He provides system analytics, product comparisons, finance studies, energy audits and everything else to make the switch to renewable energy easy for his customers.


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2 comments


  • I like how you say that polycrystalline solar panels can save you money. It would make sense that if you are already spending a lot on the panels you would want something high quality but affordable. My sister is looking to put solar panels on her roof now that she lives in a more sunny area, so she’ll have to find out if polycrystalline ones are good for her. http://joeswindowcleaning805.com/cleaning

    Gloria Durst on

  • In order to conserve energy and money, my husband and I are looking to get solar panels. Thanks for sharing all this information to help us choose the best option of panels. I didn’t realize that there were 4 different grades, but as you suggested, we’ll be sure to go for the A grade. http://www.southernair.com.au/solar-panel-installation-tasmania.htm

    Annika Larson on

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