How To Check the Quality of Solar Panels? (10 Quality Criterion) is reader-supported. When you buy something through links on our site, we may earn an affiliate commission.

The shift from conventional sources to natural solar energy is growing immensely. The shift means purchasing the solar panels and ensuring that the quality of the panel is such that it gives optimum power.

How to Check the Quality of solar panels? We cannot be deceived by the look of any equipment, especially the solar panels. We need to verify specific criteria, including the standards and technical specifications. There are several criteria to evaluate before choosing solar panels. The greater number of criteria satisfied indicates that the panel is more reliable.

This article will explore the various criteria to evaluate solar panels. We shall also try to address where the panels could go wrong. Let us get started.


The International Electrotechnical Commission has established several standards governing the commercial distribution of solar panels. The manufacturers of solar panels need to satisfy these standards to trade their products in the international market.

Let us look at the standards.

IEC 61215 – Crystalline or IEC – Amorph – These standards govern the solar panels’ electrical parameters and mechanical stability. The manufacturer needs to get the design of the photovoltaic modules approved for use in the land and for extended use to get the Guarantee of Quality certified.

The IEC 61730 deals with other qualities of the panels, including prevention against shock, fire accidents, and further damage due to mechanical and environmental situations. It also compliments the IEC 61215.

Top 10 quality criteria for solar panels

Now that you have decided to purchase a solar panel, four main primary aspects must be satisfied and obtained.

  • Certificates
  • Certificate of Standard
  • Laboratory test
  • Quote

Once you have successfully obtained the above clearance, you need to look for more details in the documents and technical sheets of the panels. Let us look at what to look at in each of them.


Guarantee is an important aspect to look into. What will you do if your panel stops functioning all of a sudden? There should be an adequate return on time for the investment made. The manufacturer should give you at least 25 years of minimum manufacturer warranty. You need to enquire about the warranty beforehand. If you don’t find the details, it is not a good sign. You need to ask the installer about the guarantee for sure.

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The price of the panels is always expressed in terms of cost by Wc. If a manufacturer offers you low prices for a better feature, it is a sign of inferior quality.

Make sure you obtain quotes from several manufacturers before choosing one of them to place your order.


Before you place the orders, make sure you undertake basic research about the manufacturer. Check about the following details of the manufacturer.

  • How long has the company been in the market?
  • How much warranty are they offering?
  • Reviews in the public forum
  • After-sales service

Solar Panel Technology

Choose the panels which meet your need for electricity. There are three kinds of technology prevailing in the market – Polycrystalline, Monocrystalline, and Amorphous. There are pros and cons associated with each of them. Review all of them entirely and determine which one matches your requirement.

The efficiency of the solar panel

The efficiency of the solar panel is the yardstick that shows the relationship between how much energy the solar panel uses to produce the optimum output. Efficiency does not explain the quality of the equipment; and rather, they assist you in choosing the right PV panels based on your configuration and installation.

A smaller rooftop ensures higher efficiency than a rooftop that has larger space. The efficiency of solar panels is dependent upon several factors. But an efficient panel must give you a performance rate between 12% to 20%.

Power Tolerance

Power Tolerance is the amount of power output you yield from the solar panel. A best PV solar panel gives you a “Positive Only” power tolerance, and it means that you will get the minimum guaranteed output at any cost.

Temperature Coefficient

The temperature coefficient is the electrical behavior of the solar panels from a standard temperature of 25 degrees. The lower coefficient, the better the solar panel is. If the coefficient is higher, the PV panels will not produce much electricity. It also depicts a lower-quality solar panel.

  • Average coefficient – 0.50% – Reasonable performance
  • Lower Coefficient – 0.30% – Best performance
  • Higher Coefficient – 0.70% – Low Performance
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Frame of the solar panels

The solar panels should have a sleeky finish. The angled contacts shall be joined and anodized to protect the equipment from erosion. The edges must not be sharp, and the design shall be integrated into the roof.

Cables and By-pass Box

Flip the solar modules and inspect the bypass box. It should have a proper diameter and made from silicone. Also, check the bypass diodes. These enable the solar panels to produce electricity even if there is shade.

Protective Film

Make sure the protective film at the flip side of the panel is placed well without any air bubbles and is flat. If there are air bubbles, it means inferior quality.

What are the control factors for a Solar Panel quality inspection?

There are several control factors for the quality inspection of the Solar Panels, and let us look at them.


Before you begin the production process, you need to select the cells that may be combined to form the solar panel. You also need to check the glass control process for transparency control and mechanical resistance and verify the lamination time.


Once the solar panels are fully assembled, the manufacturers need to perform a Pre-shipment Inspection (PSI) to check the conformity with customer specifications.

Several elements of the panel are inspected, and the following are the end-to-end verification process checklist:

Visual Inspection

The following aspects need to be checked in the visual inspection.

  • The appearance and cleanliness of the product
  • The product’s overall appearance, batteries, inverters, cables, and accessories. They must be free from damage, dents, dirt, scratches, etc.,
  • Make sure that all the corners are attached firm and tight.

Dimension Inspection

  • Length
  • Width
  • Thickness
  • Diagonal Differences
  • Labels

Function & Special Tests

Before testing the panels, you need to check the product specifications for all the promises given by the manufacturer.

  • Power
  • Voltage
  • Discharge testing
  • Current Test charging
  • Hi-pot test
  • Temperature Check
  • Polarity Check

Assemble a set of solar panels and check if its works well.

Logo, Labelling, markings check

  • Barcodes
  • Logo
  • Label & Marking
  • Rating Label

Packaging Inspection

  • Content and quantity of the items and accessories in the pack
  • Damage-free packing
  • Shipping marks and labels
  • Retail Packager artworks
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Standard Test Conditions

The parameters of the solar panels are tested and measured at Standard Test Conditions (STC). The STC recommends a temperature of 25 degrees Celsius and irradiance of 1000 W/m2 along with an air mass of 1.5 (AM1.5) spectrum.

These conditions represent a sunny day in spring and autumn when the cell surface faces completely over the sun.

Common solar panel defects

While testing the solar panels, you might find that the following defects are prevalent.

  • Scratches on the frame/glass
  • Glue marks on the glass
  • Poor sealing – you may notice a gap between the frame and glass
  • The lower output than the one stated in the datasheet
  • Lower FF than the promised one
  • Dirt marks on PV module
  • Gaps in the corner of PV frame
  • Poor quality labels

Upon all this, make sure you undertake the rubbing test. Rub the label for 15 seconds with a mix of alcohol and water. This test ensures that the label at the back of the panel will be readable even after 25 years.

Take Away

Checking the quality of the solar panels before putting them to use is very important to make sure you detect the defects. There are several inherent limitations of the solar panel, and if you take a certain step towards rectifying or finding the alternative, you can certainly solve all of them.

The first most crucial step in choosing the solar panel is to select a certified solar manufacturer. This is important to ensure that the solar panels are manufactured according to the quality standards.

The next step is determining the quality of the solar panels. The PV quality requirements need to be included in the manufacturer’s contract.

Based on the quality requirements, the manufacturer produces solar panels. You need to perform independent testing to determine the extent to which the requirements have been satisfied. You can perform either a Visual test or a Flash test.

So from now on, you need not worry about the quality of the solar panels.