Kirchhoff's current law, or KCL, is based on the law of charge conservation. It states that the total current entering and leaving a node in a circuit is equal. Currents leaving the node have a minus sign, while currents entering the node have a plus sign. By algebraically summing the currents at a node and integrating both sides with respect to time, the total charge at the node is determined. According to charge conservation, the net electric charge at any node remains constant, ensuring that the node stores no net charge. So, if the net charge is zero, the total current is also zero, validating KCL. KCL can be generalized for a closed boundary by treating a node as a closed surface condensed to a point. Consider a solar panel consisting of parallel current sources. KCL can be used in this case to find the combined current from parallel current sources by algebraically summing the individual currents at a node.