I am planning to have a shed/ workspace in my back garden where I can move all my electronics stuff. I'm planning to have a 40 to 60 watt solar panel charging batteries and then running through an inverter to power my soldering iron/other stuff and with a small light. My question is how will I be able to heat this place for periods when it is cold? It will be quite small, only a few metres across so I want it to be small, non-obtrusive and safe. I have 14 watts of solar panel that I can mess around with(1 4watt amo and two 5 watt polys) already but I'm not sure if that'd be enough power.