New to PPM: There is now the option add a fan to your purchase of the Excel NE Sun-Mar composting toilet. The fan costs $50 and can be powered by a solar panel, which costs $150.
The Excel NE:
The Excel design means that the three chamber unit can be specifically designed for those with no continuous 110 volt supply. The Excel NE does not come with a fan or heater but the 12 volt fan should be installed if you need to install the toilet with any bends in the vent.