### Instruction: Why did my portable solar panel not work when I plugged it into the solar receptor on the side of my camper van?
### Response: Solar is a lot more complicated than just a panel and a battery. Even if you have a system that is pre-wired for solar panels, there is no guarantee it will work right away. This can lead to much frustration and the need to learn more about electrical systems than one may wish. First, a solar controller is needed for all solar-powered systems. Solar controllers regulate the incoming energy, and limit the amount of watts a system can support. Many solar panels come with a solar controller built in, but if you have a system pre-wired with existing solar panels that you are trying to add to there is likely already a solar controller. Adding an additional controller will prevent the new panel from working. If one does not know about solar controllers it can be very difficult to figure out, and may lead to angry overnight Amazon shipments of multimeters to determine what is breaking. However, multiple solar controllers is not the only potential problem. Different solar panel manufacturers have different cord types and connector types, and even within a type of connector there is the idea of “polarity” - the direction a connector needs to be plugged in. This can also lead to internet research, frustration, and more overnight Amazon orders of polarity switching adaptors. If one is especially unlucky it will rain all day once all parts finally arrive, delaying testing of the system.