A weapon ahead of its time, the Electro Arrow is basically a self-contained TASER device. It is a common item for most genre archers and Hawkeye in particular favors this trick.
The OHOTMU (Official Handbook of the Marvel Universe) lists the charge as 21,000 volts, but it seems to fluctuate wildly. It’s possible that the archer can choose the desired charge when fired. Originally designed to deliver an electric shock capable of stunning a human target, the voltage has been cranked up high enough to overcome Thor, the Hulk, the Abomination, and other incredibly durable targets. (It also holds enough power to create an obvious visual effect when used. Arguably this is merely artistic license, but if not it would require an incredible amount of juice to do this.)
The trick is obviously very destructive against electrical machinery including robots. Hawkeye has used it to great effect (if not destruction) against Iron Man’s armor, Ultron, and others.
Usually the shock is discharged upon impact, but sometimes the jolt is triggered by remote or takes effect when the shaft is grasped. The Electro Arrow has also been used indirectly by sending the charge through a conductor. Firing it into a body of water can be incredibly dangerous for all involved. The arrow also functions as a hand-held stun gun when desired.