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.
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!
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.
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.
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.