I hooked up a 2V solar panel to a small relay. The relay switches at 9V. When I have light shining on the panel it puts out aorund 3-4V, but when I hook it up directly to the relay it drops to V and doesn't switch the relay. Why? and How do I fix it?-2V Mono-Crystalline Solar Panel -JWD 7 4 reed relay
Your solar panel output too little current that cannot be used to power the relay. Change the panel into 2V 500mA type shall work.
I suspect the voltage is OK but the amount of current the solar cell is capable of delivering is less than the relay coil needs to operate. The current the relay tries to draw overloads the PV. You need to add additional PVs in parallel to operated the relay coil. An alternative is to use a low current draw relay coil or use a transistor switch. Hope this helps, NewtonLaw
Do you know what is the rated Peak watts of the solar cell and the current needed to operate the relay. The power needed to operate the relay can be found from 9V * operating current, and that should be lower than the peak output power of the cell (perhaps significantly less as the peak power is produced only at high solar radiation levels. Another factor is whether the curves for the solar cell match the load. Typically the solar cells have a knee type diagram for the VI relationship, and that is why they need Maximum Power Point trackers to deliver a good power output.
There is no ampere output listed for the solar panel. There is specs indicating the relay has a 200 ohm coil. This means the current required for the relay is 0 ma. The solar panel should supply that much. Check the resistance of the relay coil. It sounds like you have the relay coil in series with another resistance, such as a loose connection or a corroded connection. If you can, disconnect the wires from the solar panel and twist the two wires connected to the relay coil, and read the resistance of the two wires connected at on end. A high resistance will indicate a problem in the wires. TexMav
