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Ebay solar panel sizes; how to avoid getting ripped off

Ever wondered why your eBay solar panel doesn't produce anywhere near what it should do? Maybe you've been scammed like a heap of other people, by false advertising sellers on eBay.

I'm in the market for another 12V solar panel, for the top of our Dmax's Canopy. I've bought a couple over the years, and each time I'm in awe of how much cheaper they've become. However, what I've discovered just recently, is a lot of 12V solar panels being sold on eBay are falsely advertised.

Ebay solar panel scam

Is your eBay solar panel performing as it should?

Check the solar panel dimensions

This false advertising purely relates to panel sizes, and claiming that a panel is rated to a higher wattage than what it actually is.

I'll give you an example:

The panel I'm chasing is 200W, and I know that a 200W panel should be 1580mm long, by 808mm wide. Now, I jump on eBay, and I flick through the results, and open a few different options up. If you check the dimensions, some of the panels being sold as 200W are only 1430 x 680mm. On the surface, that might seem ok, but dig a bit deeper.

I compare the details, and they are exactly the same, except for the sizes. 18V max power voltage, 11.1A max power current, cell efficiency of 17%, mono panels and standard test conditions.

How is it possible for a panel at 1.27m2 to put out the same wattage as one at 0.9724m2? It's not, and these eBay sellers are breaking the law by false advertising, and selling you a product that isn't what you think it is.

It gets even worse - there are flexible '200W' panels on eBay at 1070mm x 810mm (0.86m2). That's a 47% size difference, with virtually identical specs.

Now, I understand there may be *some* variance in cell efficiency, and where the panels start compared to their borders, but not 47%. These eBay sellers are being totally unethical, and people are buying them!

Solar panel wattage vs size

Is your panel too small for the wattage advertised?

What to look for

12V mono solar panels with a cell efficiency of around 17- 20% should be roughly 0.0064m2 per watt. If there is a substantial variance from that, you are being misled. With that in mind, here's roughly the sizes you should be looking at:

80W panel = 0.51m2

100W panel = 0.64m2

120W panel = 0.77m2

150W panel = 0.96m2

160W panel = 1.02m2

200W panel = 1.28m2

250W panel = 1.59m2

If you want to know that the panel you are looking at is actually the wattage advertised, do the maths above, or jump on a reputable sellers website (like Redarc, Projecta, Bosch or Australian Direct) and compare sizes.

Solar panels on our camper trailer

2 x 200W panels on our camper trailer, at the correct size that they should be

The panels on our camper trailer came from Low Energy Developments, and we've been very happy with them so far. You can read more about the new panels, batteries and the overall electrical upgrade here - Camper Trailer Electrical Upgrade.

PWM controllers being sold as MPPT

Unfortunately, the false advertising doesn't stop there. The next most common false advertising for 12V solar panels relates to the type of regulator used, and advertised. These are normally known as PWM and MPPT.

The latter is generally considered the premium style, and the manufacturing costs dictate there should be a price difference. If you are getting a panel with an 'MPPT' regulator for an amazing price, chances are its probably a PWM in disguise.

MPPT ebay being sold as PWM

Is your regulator really a MPPT?

Buyer beware:

People have been buying solar panels off eBay for many, many years now. Many of the cheap ones are not going to be comparable in quality to the high end units, but they have proven themselves to be reasonable and great value for money.

However, its buyer beware; do your due dilligence before handing your cash over to some scumbag on the other side of the world who thinks its ok to mislead their customers.

10 comments… add one
  • Marcus February 13, 2018, 11:49 AM

    Excellent article – I’ll be saving his one. Thank you. One further ‘picky’comment, you spelled the abbreviation for mathematics wrong – its ‘maths, not math’. We’re still in Australia aren’t we?!

  • Aaron Schubert February 13, 2018, 7:35 PM

    Cheers Marcus. Will fix that!

    Aaron

  • Kevin Lee May 2, 2018, 3:21 AM

    Hi , what does cell efficentcy mean , you say between 17/20% ?? , cheers Kevin

  • Aaron Schubert May 3, 2018, 8:20 AM

    Hi Kevin,

    Like everything in life, there are different qualities. Solar panels can have different efficiencies depending on what they are made of, and how they are made. They naturally lose efficiency over time, but the cell efficiency quoted when new is how well they convert light into power.

    Aaron

  • Sam August 1, 2018, 2:25 PM

    Hey mate, where did you get the info from regarding the ratios of metres squared to wattage?

    Cheers, Sam.

  • Aaron Schubert August 1, 2018, 7:28 PM

    Hey mate,

    From memory Redarc and a few other reputable suppliers. Any reason you are asking?

    Cheers
    Aaron

  • Sam August 1, 2018, 7:46 PM

    Hey mate, thanks for your reply.

    I’m thinking about using that formula to justify my bid to get my money back and/or get an extra panel from a supplier on eBay based on the false advertising. I just wanted to ba able to cite the information from somewhere a bit more “official” rather than a from website blog that I read. Hope you understand what I mean!

    Cheers. Love ya work.

    Sam.

  • Aaron Schubert August 2, 2018, 8:22 PM

    Hey mate,

    I do completely understand what you mean. It’s pretty straight forward – ask them how one supplier sells a panel thats substantially larger with identical specifications. It doesn’t compute – you can’t physically reduce the size of a panel without increasing the efficiency.

    Redarc are very reputable, and should have the same efficiency specs as your eBay ones

    My brother went through the same process and they didn’t want to play ball. Eventually he did get some money back, but it wasn’t much

    Aaron

  • Jman October 2, 2018, 8:38 PM

    Cant go wrong with the basic math to prove its false advertised. However from my observations you still loose around 15-20% panel wattage in many places depending on season. For example my 100watt by area panel only gave 80watts no matter what i did in spring victoria.

  • Aaron Schubert October 4, 2018, 10:34 PM

    Hey Jan,

    Yep, it needs very specific conditions.

    Aaron

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