An option agreement isn't a lease yet. The developer is paying a small annual amount, often in the range of tens of dollars per acre, for the exclusive right to decide later whether to sign a long-term lease, usually after they've studied interconnection to the grid and gotten permits. Most options never convert. So the $35 an acre is real money and the big lease number is a maybe.
If it does convert, the rent per acre is typically far above what cropland earns from farming, which is why these are showing up as a genuine new revenue stream on ag land. The tradeoffs are the term, commonly 25 to 40 years with extensions, and the fact that you can't farm the covered acres during it. Whether the ground comes back as farmland afterward depends almost entirely on the decommissioning language, whether the developer has to remove posts and foundations, restore grade, and relieve compaction, and whether that obligation is bonded or just promised by an entity that might not exist in 2060.
On financing, an existing option or lease encumbers the title, and lenders read it. Some will want a subordination agreement so their mortgage sits ahead of the solar interest, and the developer may refuse. That's a common place where a purchase slows down or dies. Ask your lender directly, in writing, how they treat a recorded option on the parcel you're looking at.
The part the agent probably won't raise is the tax treatment. Converting ag ground to energy use can knock it out of a use-value assessment program, and some states apply rollback taxes for prior years when that happens. It varies by state and sometimes by county, so that's a question for a local attorney or assessor before you price the bonus into the offer.
