When you're looking at buying cheap solar panels there are several main points you need to be aware of
. These are different for new or used panels, and different again for the do-it-yourself option.
Perhaps the major consideration for new solar panels is the lifespan of the units. There seems to be no end of cheaper, glossy black solar panels available, but why are they so much cheaper than the blue crystalline units? Most of the cheap panels are made from either amorphous silicon or are CIGS thin film units. These work fine when they are new but don't have the resistance to sun damage that more expensive units offer. Obviously, buying those cheaper panels second hand is not a good idea.
There is also the aspect of frame quality for new panels. The frame needs to be corrosion resistant, very well sealed and able to survive stresses like minor twists and bends which will occur during installation or relocation. Poorly constructed panels may well suffer damage during handling. The effect of this damage will not be noticeable for some time.
For used panels, corrosion is the most obvious first thing to look for. Often used panels come from harsh environments and are being sold simply because they do not function well any more. That may be a small problem to a skilled electrician who can repair the wiring and connections in the panel, but how many of us fit into that category?
Perhaps you're interested in the Do-It-Yourself option. Buying a guide for this is simple enough, but locating the parts necessary to build the projects may be a little more difficult. Since solar cells form the basis of these projects it is a good idea to see if you can find a source for these before laying down the money for the guide. Also take into account what country the guide was written for. Different countries have different power supplies, laws and availability of the materials needed for these projects.
To get a good deal on cheap solar panels you'll need to do a bit of research. However if you have some knowledge of what to look for and where to look you'll be able to find some excellent deals.