I would buy the lot with cash from my solo401k account for what I originally purchased the lot for personally 5 years ago.
ANSWER: This transaction would be prohibited because you cannot transfer, exchange or sell and asset such as a lot that you already own to the solo 401k or vice versa. Reason being, you are a disqualified party along with your spouse, kids and parents to name a few. Please click here to learn more about the prohibited transaction rules.
Chris in Maryland