Those Cheap Chinese Solar Panels

Are Chinese solar panels any good? Well, most if not all consumer solar panels are made in China. So what makes them cheap? Usually the actual construction of the panel and some of the deceiving advertising the sellers use.

With the anticipation of grid outages or just adventuring out into the wilderness, it is often you will need to recharge your cellphones, radios, or flashlights. Depending on your power requirements you must choose the best, reliable, efficient, and most convenient panel to satisfy your charging requirements. Cheap panels will suffer in performance. Some cheaper panels don't have mounting frames to keep the cost down but that doesn't necessarily mean they won't perform satisfactorily. For portable operation a panel without a frame might be desirable.

There are many types of panels on the market today. They are found on Ebay, Amazon, and a number of websites including banggood.com and dx.com out of China (so far shipping charges are not that bad and rather quick). The more square inches of panel area, the higher the wattage it will provide. All panels are rated in watts (output). For the most part they all seem to perform satisfactorily. What differentiates between cheap panels and great panels is the physical construction of the panels and the performance of the charge controller, if any.

There are also different types of panels. Monocrystalline, polycrystalline, and amorphous. The latter I do not recommend due to its fragile glass surface and limited life expectancy although they will put out high current initially. Some of the newer 100 watt monocrystalline panels are even flexible so they can be folded, carried around, and stored easily.

Maximum wattage is only obtained on a bright, cloudless day with the panel facing directly into the sun. 

Most of these portable panels are just the basic panel itself and some have a charge controller built onto the back of the panel. Hooking up panels is explained on this page. The charge controllers may include two USB sockets to charge your cellphones or other USB devices and a 12 volt output but this is where the problem lies. Is the 12 volts actually 12 volts or does the output rise as high as 21 volts unloaded? With a constant current ample load this won't be a problem. If the load changes drastically like a 12 volt AA battery smart charger, it could damage the smart charger.

Update 11/7/21: In troubleshooting one of these foldable portable 100 watt panels, I took the distribution box out because the wires broke off the box. I noticed a simple USB buck converter for the 5 volt USB sockets, but the panel connections went straight out to the 12 volt jack. This confirmed my suspicion. There is no 12 volt regulation. This means if you had a sensitive load say less than an amp connected to the 12 volt socket, you'd have almost 21 volts going into your load be it a radio, charger, battery, etc. This will immediately damage your equipment! The picture below shows what's inside the little box. The metal strips soldered to the back come out to the front as seen by the screened writing where it says DC+ and DC-. You can follow the circuit traces right to the 12 volt jack on the lower left.

So if you need a steady 12 to 14 volts, you need a buck converter or regulator between the 12 volt panel connector and your equipment.

Also what if you need more current? Can you wire them in parallel to get more current or will the charge controllers fight each other and eventually destroy themselves?

So how do you know what you're getting? I've seen 100 watt panels with a very small gauge power cable coming out of the back. There has to be a loss of power with small gauge cables. Also the connectors usually cannot handle the current, about 6 amps, a 100 watt panel provides.

Current U.S. pricing (as of fall 2021) of good panels is approximately US$1.70 per watt, or US$170.00 for a 100 watt panel. Some Chinese panels specify a wattage that don't seem possible. Be wary of a panel sale claiming 100 watts and only costs $29.00. This is impossible. What they claim in the ad is 100 watts but this is the capacity of the charge controller and not the output of the panel.

Panels with charge controllers mounted on the back are usually sealed and there are no specifications as to what it provides and how the charge controller operates and very little documentation as to its use.

Ideally you need a panel that provides a steady 12.6 to 14 volts output. If not, your external battery chargers will not operate properly and just hooking the panel to a battery will damage the battery and panel. Again, read this web page for proper connections.

If the solar panel is just the panel, you should see two wires, or a cable, or two terminals on the back of the panel and nothing more. Care should be taken not to put a lot of tension on these connections otherwise you can pull the terminals off the back and render the panel useless.

Some panels have a small plastic "box" where the wires come out but you won't know if there is some sort of smart technology in the little box or if it's just a robust connector housing. A quick way of checking is to place the panel in the bright sun and measure the output. If it goes as high as 21 volts, it is most likely a connection only and nothing else. If the voltage is on or close to 12 volts and doesn't rise to more than 14 volts, it most likely has some electronics.

Care should be taken not to short these terminals because you may damage the controller.

Good quality commercial panels will have a label on the back specifying its output parameters as shown below.

High quality panels will have a weather proof junction box as shown below.

Panels can be wired in series for a higher voltage or parallel to provide higher current. Again, study the glossary on this page to help you understand series and parallel connections.

 

 

Copyright 2021 by Rick C. Ver 0.19 Nov 8, 2021