Either you could purchase rectifier diodes of the required ratings or I have seen many people series avalanche rated diodes such as 1N4007 or SF1600. There are probably better suited diodes for a few extra $$.
The most interesting solution that I have seen to avoid an arc around the diode casing is to place each string inside of silicone tubing filled with oil and sealed with hot glue.
I am curious though to read other peoples ideas.
Good luck,
Matthew Edwards_______________________________________________
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