Spouse contributions to Solo 401k

[Jim P.]

I'm planning to set up a Solo 401K, but I'm having trouble finding information about married couples with Solo 401K's.  Should my wife and I have separate Solo 401K's?  Can one Solo 401K be shared between spouses (both contributing to the same account)?

I'm self-employed with no employees and my business will net about $100K this year.  My wife actively helps with the business, but I've never explicitly paid her with a W-2 or anything like that.  What's the best way to maximize the amount we can contribute to a Solo 401K?