Solar water heaters will work pretty much anywhere, you just need an area of unobstructed southern exposure.
They can be pretty simple in design. Some people make them by hand out of scrap material.
These usually circulate the water itself through a collector, and obviously with a setup like that there's going to be an issue with water freezing in the lines in winter at night.
The commercially available designs these days use arrays of glass vacuum tubes to collect the heat. A circulating system of non toxic antifreeze is used to transfer the heat from these tubes to an indoor hot water tank.
It's also possible to make a solar air heater, to augment the existing space heating system in your house. These are even simpler than solar water heaters, and can be easily made by hand.
Aside from solar systems, you can also augment, or replace, your hot water tank with a tankless water heater. These burn no fuel until a tap is turned on, heating water only on demand.