1. Solar panels need a huge capital expenditure up front.

2. Wind power works better for farmers and provide a smaller footprint. Drive on I-80 in Iowa on a clear night and you'll see the wind farms blink their red lights in the distance. Farmers can lease their land for wind turbines, and the generation companies take on the regulatory / capital / politcal risks, etc.

3. Farming is more or less free market based, and often farmers can let their grain sit in a silo until the price is optimal for them to sell. But for a given location, there's only one power company that you can use, and typically the power companies don't like people putting solar panels on the grid. In many states (like in Idaho) there's regulatory capture or weird politics preventing people putting solar panels up on their own land. (Again Idaho)

As a side note, agriculture uses up lots of water in deserts (more so than people), so it seems like in desert spaces like Idaho, solar would make a lot more sense than agriculture would. And we should move the agriculture to where the water naturally falls from the skies.

There was also a huge move by farmers towards growing corn and selling for ethanol because E-85 was seen as some future fuel. Many farmers I know went all in and switched from regional crops (this was in ND), such as sugar beets, soybeans, and spring wheat to corn to fuel this thinking this some kind of energy gold rush.

Then economics, lack of infrastructure and incentives buried it in a few years. Farmers were left holding the bag. Many were not happy they had made a huge move into this new "renewable" energy, only to get burned in the end. The same farmers I know have scoffed at windmills and solar farms.

E-85 really lost a lot of farmers willing to use their land for something that won't pan out. The ones I know went back to growing what sells and grows the best in the market. Trying to tell a farmer that solar panels on his land where he grows food to feed his family is going to be a tough sell now.

In California, PG&E charges you for putting solar on their grid and they'll pay you a penny for your extra electricity.