Annual Electricity Generated is 26,300 TWh/year.

Over 6× total U.S. annual electricity consumption (~4,100 TWh/year). This is enough to electrify everything in US.

The ethanol argument is a dying cause.

The argument about corn is to actually stop the waste of the fertile land for fuel. Solar panels can be installed wherever they're necessary, no one is proposing replacing the corn in situ.

The math the person you're replying to was talking about was solar power vs ethanol. While your 800 m^2 sounds like a lot of land area for enough solar panels to fully charge a large electric truck, it's basically nothing compared to how much land area you'd need to grown enough corn to produce enough ethanol to power a similar truck. It's about 500 times as much land area, a fairly obvious result when you consider you get solar power from the land basically every day and corn once a year. Growing plants for ethanol is dumb.

Of course the benefit of a combustion engine is that you don't need to grow corn to make ethanol for it, at least as long as you can get fossil fuels out of the ground and the enemy doesn't disrupt your supply chain for drilling and refining fuel oil. But that's irrelevant since that wasn't the land-use comparison the parent poster was making.