What are Bypass Diode, Blocking Diode and Isolation Diode?

What is the difference between a bypass diode, a blocking diode and an isolation diode? 


A blocking diode is used to prevent batteries from "leaking" current.  You do this by placing the diode on the positive line between the module and the battery.

A bypass diode is wired in parallel with a module to divert current around the module in the event of shading.  Bypass diodes are pre-wired in some modules and usually sufficient unless the module has a higher voltage.

Isolation diodes prevent the loss of current in the event that one string of modules in the array fails. 

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