"I've seen some really cheap SunPower Flexible Solar Panels, what's the difference between theirs and yours?"
SunPower are global leaders in solar technology, and their name is synonymous with quality and reliability. Because of this, some retailers use their name unscrupulously.
They do this by:
• Using the words “sun power cells” – which is technically true, cells are powered by the sun, but they are not “SunPower” cells
• Genuinely believing that they are SunPower cells because of what they have been told by their supplier
• Actually using SunPower cells, but using the reject cells which do not produce the power output stated
How do you spot a genuine SunPower cell?
Short of buying two panels and chopping one up (the backing on SunPower cells is distinctive, see image above), there’s a few ways.
Firstly, SunPower make a back contact cell. What this means is that the cells connect to each other in the string via the rear of the cells, not the front face. As such, they do not have lines running across individual sections of the cell, nor do they have tape connectors running across the front of the cell.
Below is images from two listings which have "Sunpower" in the heading on eBay. You can see the lines running across the front of the cell, meaning this is absolutely not a SunPower cell.
What if the product photos aren't detailed enough to see up close?
If they dodge your question and cannot provide any proof/information to back up their claims, back away quickly.
While they aren’t likely to provide documentation from their suppliers (to protect their own products from being copied), chatting to them and gauging their responses will give you a feel for whether they are being truthful.
If its really SunPower, they cost more to make and as such cost more to buy. The would have back up to prove their claims if legitimate.
Are all SunPower cells the same?
No. SunPower grade their cells according to their efficiency and aesthetic appearance. They take the highest specification cells and use these in the production of their own SunPower branded solar panels.
They then grade the cells further and on sell these to the open market. The higher the efficiency and aesthetic appearance, the more the cells cost.
The problem then arises that while some retailers can honestly say they have SunPower cells, they may be using a lower grade cell. Whilst this lower grade cell will have a lower efficiency (and therefore power output), then may continue to use the efficiency rating attributed to the premium range.
This means that a panel marketed as a 100W panel may not actually be 100W after all. Alternatively, they might not give you the efficiency rating at all, and just overstate the power of the panel outright.
How do you know a SunPower panel is actually the watts stated?
To work out what's really going on and determine what you are actually buying, is simple math.
Start by counting up the number of cells on the panel shown (they are squares with corners cut, which may or may not be cut into 2 or 3 pieces), then divide the panel wattage stated by the number of cells.
For example (NB. this is a random image and not a panel in question):
Let's say this panel is stated as being 200W.
It is 6 cells wide and 8 cells long:
6 x 8 = 48 200W/48 = 4.1666W/cell
Then have a look at the table below, which shows the premium SunPower cells available, and their price per cell (there are different generations and differing grades - this information is freely available on their website).
If the number you get is over 3.64W, then you know for sure they’re telling porkie pies, because the Ultra Premium Performance Cells are the highest performing cells that SunPower makes available for purchase by distributors (there are higher performing cells, but SunPower keeps these for their own panels).
Let's do another example (again, just an image grabbed from Google):
This panel is listed at 100W.
4 x 8 = 32 cells
100W/32 = 3.125W/cell
Now, as you can see, the watts per cell on this panel are below the lowest wattage on the price list above.
When SunPower manufacture their cells they have exact standards that each cell must meet in order to make it into their own panels. Everything else is on sold to distributors (these are those in the table above), who can then manufacture their own panels, still with "SunPower" cells, just not meeting the specifications set by SunPower for their own panels.
3.125W, however, is well below the lowest cell that SunPower list, which means that these cells are very low quality. This is what is called "Out of specification" cells and are actually rejects for third party sale.
What this means in practical terms, is that this panel, at 100W, will be significantly bigger than a 100W panel using a higher grade SunPower cell, ie. you get less watts per area - and space is always at a premium on top of a van or fourbie.
What about the laminate?
The laminate is the top layer on the panel and is what stands between the cell and the elements.
Flexible panels should be laminated with ETFE, which is manufactured in Japan or US by companies like Dupont. It is a fluorine-based plastic, designed to have high corrosion resistance and strength over a wide temperature range.
If a manufacturer/retailer uses ETFE they will advertise it, as it is about 6 times more expensive to purchase compared to PET or TPT.
Flexible panels are not supposed to be made with PET. It's a cheap manufacturing shortcut and will significantly reduce the longevity of your flexible panels.
Ever seen what a plastic water bottle looks like when left in the sun for 12 months? Totally discoloured, turns milky and is no longer clear. They break down in the UV and your panel loses its ability to receive sunlight on the cells.
These are the type of panels that melt, blister, delaminate, catch on fire etc and are where the horror stories about flexible panels comes from.
ETFE vs PET
What if I want more than one panel?
The vast majority of product pages for cheaper flexible panels state that they cannot be connected in parallel. If you are planning on purchasing more than one, or hooking it up to an existing panel, this should be a big red flag to bypass this retailer.
If panels are not designed to be joined together then doing so will result in failure of the panel.
Look for information regarding how many panels can be joined together.
Our AllSpark range of flexible panels and blankets use genuine, high specification SunPower cells because of their high rates of efficiency (which, simply put, is their ability to convert sunlight to electrical power in a comparable surface area to other cells), ability to deal with the high temperatures found in Australia, their performance in shade and their longevity.
The AllSpark range also uses premium ETFE laminate, which protects the cells long term.
This means you will be producing the highest amount of power possible from the smallest physical size panel, for the long term.
A solar system allows you to go off-grid, escape the crowds and enjoy your time away from the every-day. There is no point going to the time and effort to fit panels only to have them quickly reduce in efficiency, and then have to replace them a year later when they begin to peel or discolour, or worse, leave you in the middle of nowhere with an under performing panel.