I have some leftover solar panels and want to try connecting them straight to a (correctly sized) water heating element -> 50 gal container of water in my garage, and see if I get any meaningful heat in Fall/Winter. That would save the cost of a battery, charge controller and inverter.

If successful, phase 2 would to be to circulate that heat into the house.

Of course it's way less efficient than a solar water heater, but reduces a lot of the complexity/cost and potentially lets me dump excess solar.