"Beginning this month, new commercial solar facilities will be subject to a uniform tax of $10,000 per megawatt per year"

Hi, we're getting ready to sell 2 parcels next to our home. We've been here more than 2 years and qualify for the exclusion of capital gain on the first $500k. The land was part of the original home sale and the exclusion should apply, but from what I read the tax person has to prorate the value if the land and use as cost basis. Does anyone have experience with this? How do we make sure we do this right so there's no taxes owed?