Utility project manager here. It will be in the order of millions, and you will have to pay for any new substation build and/or upgrades to existing substations and lines to support the additional capacity. This will be additional millions. All of this will require additional engineering resources to redo the protection, update the SCADA, work through all of the compliance, etc etc, which will add a few hundred thousand on top.

It’s not cheap, and maybe 5% of all submitted solar projects actually go through because investors/developers aren’t exactly savvy on what’s required to make it happen on the utility end.

What you would do in your situation is approach an established solar developer and see if they’d be interested in buying/leasing your land.