Solar water heaters are usually used as a pre heater to conventional water heaters. The solar storage tanks are also of larger volume. The idea of the larger volume is that the solar tank is trying to store at least 1 days hot water usage. The solar tank on a sunny day will slowly heater the volume of hot water required for 24 hours of usage.

We do have solar operated jack pumps which can pump water like your windmill water pump but we don’t have a system that can run the existing windmill pump. We could use an electric wind mill and electric panels to run a jack pump so when the wind didn’t blow the electric panels would continue to pump water.