Choosing a Good Solar Module...

There are hundreds of manufacturers of solar PV modules today. Some have been around for about 35 years (e.g. SolarWorld AG) and others are recent start ups. Many have closed down in the past 6 months, others are well established. So, how do you know which one is good and which one isn't ??

Here are some tips...

Yield = monetary savings = carbon offset…

What is yield in the world of Solar photo-voltaics?

Yield refers to the amount of power produced over a period of time (usually a year) measured against a kW of installed capacity. Surprisingly (well not really), not all modules provide the same yield per kW. In fact variances of well over 12 – 15% can easily be found! These add up to many kWhs and thousands of dollars over the life-time of the system.

Of the vast number of makes, all offering up to 25 years’ performance warranties here is a simple, yet effective way to gain some idea of which modules perform well under live conditions…

Photon Lab, Germany, an independent laboratory, conducts tests on a daily/monthly/ and annual basis and publishes these results.

The annual results can be viewed at: HERE, and reveal that there is a significant gap, even between reputable manufacturers....


German quality

Once you are satisfied with yield, quality needs to be examined. A typical system should last well over 25 years. Quality is therefore paramount. Some companies buy-in their wafers, assembling the modules themselves. Others are involved in the entire process, from research and development, wafer manufacturing, through to assembly and even recycling.

Some manufacturers assemble by hand! (sad, but true). Others use automated processes, which guarantee more consistent levels of reliability and quality.

And here is something really nice: some modules are 100% recyclable!




Other factors...

  - Quality of the connectors and the junction box
  - type, thickness, and quality of the front glass cover (usually tempered, at least 3.2mm, and textured to cut down glare; SolarWorld offers a 4mm thick glass!)
  - quality of the frame
  - holes in the frame to allow dew to come through
  - the angle between the edge of the frame and the glass, to allow water to flow easily
  - diodes in the module, to deal with hot spots when there is shading and quality of the junction box...most are made of plastic, some of aluminum
  - is the frame anodised or not?
 - quality of the bus system
  - material used at the back
  - nature of power guarantee, is it linear or stepped?
  - the normal operating cell temperature…the lower it is, the better it will perform under hot conditions, etc

100% recyclable

Did you know that some modules are 100% re-cyclable? After all, if we are to produce sustainable and low-carbon-impact technologies, we should consider the end-of-life impact, too. All modules offered by iEnergytech are part of a PV-Cycle group that guarantee 100% recycling of all materials.

Linear Performance Warranty

All modules deteriorate a little over time. Most manufacturers will give a warranty stating that the warranty will drop to no more than 90% in the first 10 years and then to no more than 80% in the next 25 years.

Some quality manufacturers will guarantee that any deterioration will be linear, not tiered; this translates to about 7% more yield over time.

SolarWorld AG was the first manufacturer to offer such a warranty.



















Plus Sort

A few manufacturers are now offering a plus-sort guarantee. This means that if there is a variance in output (and there always is), it will be on the plus side (as opposed to a + or – variance). SolarWorld AG offers a plus-sort guarantee on all its modules, as do WINAICO.

Here we see an example of a SolarWorld AG 4.83kW system (using 21 x SolarWorld 230W/p panels) peaking at 5.202kW! That is 7.7% above the rated wattage, which considering inverter and other losses is the equivalent of about 10% above the rated wattage...

An example of a customer user manual


Materials' warranty

This is different from the power-performance warranty. The materials' warranty on most modules varies from 5 to 12 years.

After-sales support

How well is the product supported; what is the reputation of the company? How long has the company been manufacturing modules to be able to substantiate a 25 years’ performance warranty?

For example, SolarWorld AG, a manufacturer of over 35 years, has discovered that their modules are still producing over 90% energy after 25 years...they have the track record to prove this!





















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