There are also solar water heaters that are a bunch of black pipes on a roof.

Napkin math based on Amazon/Home Depot prices

You can get a 80"x90"x95% = 2kW output solar heater for $2000

or eight 45"x70"x25% = 1.8kW solar panels for $2800

A regular water heater needs about 12kWh a day, which is about what both systems would produce.

However, a heat pump water heater is 4x as efficient, so you could get by with $700 of solar panels.

Except, a heat pump water heater costs $2000 instead of $500 for a regular electric heater.

There's also install, maintenance, and the fact that we're talking about grid prices, not home panels, but those won't fit on my napkin.