Solar black spots and Specs

What’s the story about solar – simple answer: It’s complicated. Why, it delivers less than you are led to believe; yet it is very sensible, and misinformation prevents you seeing the ‘real’ picture? Should you buy: Probably yes, but are you fully aware of what you buying? Two different buyers have asked very similar questions. For instance, my friend said they would be free of energy bills after fitting solar – $25,000 later they still get bills! A commercial entity is getting nervous about a $70,000 outlay after having heard that you can expect on hot days up to less than 20% less energy output from solar – the return on investment (ROI) would not stand up on those numbers. The obvious in all this: They did not ask the right questions about performance and reliability, they believed the mantra of free energy without considering what was the quantity of free and the quality of claims. Greenwashing and false claims become the issue.

On 17 January 2014, the Australian Competition and Consumer Commission (ACCC) successfully prosecuted and had imposed fines of  $145,000 penalty for fake testimonials and false solar energy country of origin representations. You can find the ACCC media release 003/14 on .

In direct quote from the media release is “Businesses making misleading representations can harm consumers by influencing them to purchase products, sometimes at a premium price, they otherwise wouldn’t choose to. They can also harm competitors who accurately represent their products by creating an unfair playing field.”

So CO2Land org with the help of WINTELBOFF went looking for a fair playing field specific to Australia. We found something and while it might mention Australia, we think it is applicable for all to take note of:

The Top 10 Things To Check On Every Solar Panel Specification

The message from the author is look carefully at the specifications sheet, “If the spec sheet combined with the quote doesn’t have the answers, call up the solar supplier and ask. If they don’t know the answers, that’s a bad sign”.

The Top 10 Criteria

1. Warranty.

It seems that all panels claim to have a minimum 25 year Power Output Warranty. I’ve covered how to go thru the solar panel warranty with a fine tooth comb here. But the main criteria is to check that the Warranty is backed by an Australian Entity that has to comply with Australian Consumer Protection Laws, and that it is an “on site replacement” warranty. You really don’t want to be removing the panel from your roof and going down the post office to send it back to China! Plus the last time I checked, Chinese consumer protection laws weren’t that hot. (Note: There are some excellent solar panels, made in China, these days and also some shocking ones – the best way to know if the supplier believes in their quality is to see what responsibility they take for the warranty they offer on them)

2. Cost

Typical prices for solar power systems of different kW sizes are shown here. If the cost of your quotes solar system is substantially less, then make sure you are getting a bargain, not a liability by reading this post.

If the price is much more expensive than those show, then either you have a particularly difficult install, or you are paying too much. Get multiple quotes to check which is the case.

3. Manufacturer

Do a quick Google of the manufacturer – What’s their website like? Is there a “warranty” section? Is there an Australian office? How long have they been around? Has anyone had any bad experiences with them on the forums?

4. Panel Type

Is it a mono crystalline, multi crystalline or thin film solar panel, or some wacky new technology? The types of solar panels and their pros and cons are discussed here. Make sure you are happy with the technology that you choose.

5. Solar Panel Efficiency

Unless you have a huge roof, you probably want an efficiency of at least 12%. Otherwise if you ever want to upgrade in the future, you’ll probably struggle to find any roof space left over. However don’t fall into the trap of believing that efficiency is the be all and end all of solar panel quality. You can get great quality panels at the lower end of the efficiency scale. There’s an in depth discussion on solar panel efficiency, when it matters and when it doesn’t here.

6. Power Tolerance

This is the amount that the actual power output of your solar panel can vary from the output specified by the supplier. For example a 165W module with a tolerance of +/- 5% could actually produce from 156.75W up to 173.25W.

So be aware of this number, as it will directly affect the amount of power you can get.

Some manufacturers have a “positive only” power tolerance, which means you are guaranteed to get at least the specified output from the panel and usually more. For example: a 200W solar panel with a tolerance of +5%/-0% will produce a minimum of 200W and a maximum of 210W.

7. Framing Quality

The aluminum frame which goes around the solar panel is a good indicator of the overall quality of the solar panel’s manufacture.

Look at the corners. Are they tidy joins? Are they anodized after the cut, or before. Anodizing after the cut is more time consuming, but means that the 45 degree edge is anodized too, helping protect from corrosion. Are the panels glued (bad), screwed or welded at the corners.

If looks are important to you – then you may want to look for a black anodized frame – they look damn sexy when mounted in a solar array on a roof.

8. The Backsheet.

All solar panels have a plastic backsheet glued on the the back of the panel to protect the solar cells. A flimsy backsheet with any air bubbles or signs of coming unstuck is a sign of a crappy panel.

9. Bypass Diodes

If your panel is mono or multi crystalline then these are a must. They are diodes that cost a few cents each and are put across neighboring of cells inside the solar panel. If you don’t have bypass diodes then a small shadow on a tiny part of your solar panel can stop the entire panel from making electricity.

10. Temperature coefficient.

This is especially important in sunny Australia!

The temperature coefficient is a number that describes how well the panel handles hot temperatures – where hot is defined as greater that 25 degrees Celsius.

The units of this number are “% per degC”

The lower this number, the better.

The higher this number, the more your power will degrade on hot days, when the sun is at full force! And you though that the more sun you had on your roof the more power you would get. Not if this number is too high…

A high temperature coefficient is a sign of a crappy panel. A reasonable number is about 0.5%. If you can get this down to 0.3% that is the sign of an excellent panel. Over 0.7% is a warning sign.

I’m a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and founder of My last “real job” was working for the CSIRO in their renewable energy division. End quote.


CO2Land org ponders the Castrol advertisements of some standing: Oils aint Oils. You can speculate Solar aint Solar = get the facts first.

Then there is the elephant in the room – if you brought junk panels where do you dump them? Are they not still classed as dangerous and capable of shock! We better check that out ASAP too!



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