A tricky question!
It somewhat depends on your battery size although running anything that heats from Solar is going to 'eat' your power.

A typical solar system has between 5 and 10KwH of storage. This means that (in theory) you can run a 1Kw heater for between 5 and 10 hours and that would drain your batteries. In reality you wouldn't want to do that as you would quickly kill your batteries.

The most common forms of heating here are a wood burner, oil fired central heating and/or portable gas air heaters. Each has its plus and minus.

Hope this helps rather than adds to the confusion!