Solar Panel Problems

Solar panels are so reliable that we are surprised when something actually goes wrong. Temperature fluctuations, severe weather, lightning and static electricity are all examples of things that affect them. Here are some things you might need to know in order to fix your solar panel.

If your panels are wired in series-parallel or parallel, then you can test individual panels by covering at least four of the cells in the panel. The output should drop by half or more. If it does not, then that panel is not working. Look for the problem in that panel, or other panels that are wired in series with it.

Sometimes, the voltage coming out of the system drops during the hottest part of the day. This is called “Fading in the Heat”. A 12-volt photovoltaic module is nominally designed to work well all the way to about 17 or 18 volts at 25 Celsius, so that the 12-volt current will be maintained when the voltage drops at higher temperatures. If the heat fade is more severe than this, it might be caused by weak links in the system, such as poor connections, bad wiring, controller losses or a weak photovoltaic module. You can troubleshoot this by monitoring the current while cooling the array by pouring water over it. If the voltage returns to normal, disconnect the panel from the system and check the open voltage. If it is below 18 volts, then use the shading technique above to test individual modules.
Temperature cycling, oxidation and corrosion can affect metal connections. Screws can loosen, metal can warp, and electrical resistance can occur. This all adds up to overheated connections. It is even possible that an electric arc can melt metal and burn insulation. Repair this by replacing all corroded or oxidized metal parts, possibly even bypassing burnt terminals by wiring directly to the metal strip, which is connected to the PV cells.
Usually, PV modules have a bypass diode in the junction box. This keeps the cells from overheating if they become partially shaded for an extended period of time. Occasionally, lightning can cause a diode to short out and the module’s voltage will drop. If the array is 24volt and is unlikely to get sustained partial shading, you can remove the diode. In a 12volt array, you can remove the diode without bypassing it. In any other situation, replace the diode with a silicon diode. Be certain that the voltage rating is 400 volts or more, and that it has an amp rating at or above the modules maximum current.