OK, I bought one of the Jaycar 200 W folding solar panels. It's not the best panel there'll ever be, or the cheapest, but it seems pretty good. It has a few nice features, and a few quirks.
The carry bag is slightly padded, which is nice because the two panels face outward when folded closed. I've thought of adding hardboard panels to the outside of the bag to help protect it in transport, but it's easier to just put it back in the cardboard box it came in when carting it around.
There's no glass (tempered or otherwise) over the solar cells, just a thin plastic film, which means it's less expensive, lighter weight and will arguably stay cooler. It also means there's nothing to protect the cells from flying children or soccer balls or stuff moving around in the car on the way to the camping site.
Flexible panels can be found cheaper but have a reputation for not lasting well, so getting something like this with a solid frame sounds sensible.
The whole thing is a claimed 15.3 kg (not measured). It's big and heavy, but it is portable with a bit of effort. Because of its size it's not possible to carry it in its bag holding the handles with a straight arm.
The two 100 W panels themselves look good and well made. The aluminium frame looks OK, and looks like a mid-budget frame. A stand on the back of each half tilts the whole thing toward the sun. It's very simple but it works.
The solar panel has a spring-loaded handle. The two clips to hold the two sides closed are a strange design and just keep it closed without putting any tension on the frame. The fittings look closer to the cheap end of the range.
In the small amount of testing I've done, I've seen the back of the panel hit 59 °C. (The front of the panel is a bit too reflective to get an accurate reading.)
The 5 metre long cable is marked "2.08mm2, 14AWG" and has a round outer sheath. This is a good cable.
I've seen an output of around 135 W before the controller cranked back the current (because the battery was almost full).
The solar controller doesn't have any detailed specs and is really just a mystery black box. It looks waterproof but does not have load terminals, so it does nothing to protect a discharging battery, just charge it.
The controller has a float mode once the battery is full, where it switches the power off and on with only a low current output – nice.
When not charging anything the panel has an output of about 0.67 V(!), so it will not run a 12 V device directly. To output power it needs to be connected to a battery. By momentarily connecting it to a battery the panel can be "woken up" to output 17-19 V but it turns off a few seconds later when it realises the thing it's now connected to is not a battery. This limits its usefulness.
Other solar kits Jaycar sells come with a full featured charge controller which can protect a battery from over discharge by switching off the load. They are proportionally more expensive for the solar panel power rating.
The user "manual" is just a single sheet of light weight paper. It's absolutely pathetic, and not just because it misspells "aluminium" the American way – very strange for a product which comes through Australia. It's pathetic because it contains really basic errors and doesn't contain really basic details and specifications.
The unfolded size is a bit less than 1360 mm long, NOT 1790 mm as the product description, box, and user manual all say. Someone doubled the wrong dimension from the closed panel. Yes, it made it to the box. This mistake appears to be too embarrassing for Jaycar to bother responding to the message I sent them about it.
The cable has battery clips, NOT alligator clips as the product description and box says. Again, Jaycar has not responded. The Jaycar saleswoman and I had a look at some battery clips and alligator clips in the component section and they were all labeled correctly (and sensibly!) there.
The instructions say the controller has over-discharge protection. Bollocks. The battery is not discharging through the controller.
The manual says the controller "Automatically disconnects battery at night" (ie, it has a diode) and it has short circuit and reverse connection protection (as any controller or solar panel should).
My main concern long term is the durability of the panel due to the cells being exposed. A sheet of tempered glass on the front of each of the two panels would significantly add to the cost, but provide much more protection; there's an obvious trade-off.
The lack of specifications for the charge controller is disappointing and frustrating. Because it simply clips onto a battery the lack of battery discharge protection is something to be aware of. Jaycar have other lower power solar panel kits which come with a separate charge controller which does have battery discharge protection.
Having a quick look at the printing on the box yesterday afternoon I'd say it's part of a move by Jaycar to commoditise solar panels, making them an off-the-shelf item that can simply be bought and used. This is not necessarily a bad thing. A bare solar panel connected to a solar charge controller takes more setting up, which is a barrier to mass market acceptance. This solar panel is not as versatile as that setup, but for a particular set of purposes it's plug-and-play.
Because of the incorrect details and lack of specs in many areas (I'm working out as I go how the charge controller works) I really can't give it 5 stars, even if it came with a full featured PWM charge controller and a better way of attaching to a battery. It does seem pretty good for the (apparent) intended purpose – simple charging of a car battery or sealed lead acid battery – and it gives a nice amount of power for a reasonable price, so it probably deserves more than 3 stars. So 4 stars it is.
Because this folding 200 W panel is so big and heavy and somewhat unwieldy, multiple smaller solar panels may suit some people better, being more practical. At present prices they will be more expensive for the power produced, though.
Update December 2020: This product is now marked as Discontinued. I think that's a pity because of what it offers for the price.
independent kiwi spirit of invention.