I have never considered using renewable energy for background heating in a situation such as yours. It sounds like the cabin has little air circulation while you’re away.
I personally would not use a wind turbine – they require fairly regular checking and are prone to breakdowns … and the wind does not always blow when you want it to!
If you are in a mainly sunny position (S – SW facing) I would be more inclined to use a solar water heater (probably evacuated tubes) connected to a radiator in the cabin. The water could be pumped by a little solar powered 12V pump connected to a small 12V solar PV panel. The beauty of this is that water is only heated in daylight, and the solar powered pump would only run off the solar panel during daylight hours. You would not need a battery bank to worry about.
You could, as an alterenative, put in a larger solar panel which could operate a small 12V fan as well as a small 12V pump. The fan can be located in a convenient place in the cabin to circulate the air during daylight hours – obviously it would be more efficient in bright and sunny weather.
Another thing you could do is line south-facing windows inside with black plastic, leaving a gap of several cm between window frame and the top & bottom of the black plastic. You also leave a gap of several cm between the glass and black plastic. The air between the glass & plastic warms up & the warmer air escapes out the gap at the top of the window frame. This simple technique can warm up the cabin several degrees using simple passive solar. It would also help to circulate the air a bit more – with or without the fan.
I’ve read about this but never used it at home because I like to look out the windows! You can read more about capturing free soalr energy at little or no cost in “Sunshine to Dollars” by Steven E Harris available from:
http://www.StevenHarris.net or
http://www.knowledgepublications.com
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