My living room gets plenty of sun from big, west facing windows. As the cold weather is approaching, I wanted to make a device that leveraged this exposure to sunlight to store some energy and slowly release it through the night.
The initial idea was to have a solar panel, battery for electrical energy buffer, some sort of aquarium heater, and a water tank.
Water would be heated by the aquarium heater, which would be powered by the solar panel and battery through the night (as long as the battery lasts). This setup would slowly release the water's heat to the living room.
Will this be more efficient than having just a water tank painted black next to the window? The sun would heat it pretty well during the day, and the solar panel+battery+heater might not be much more efficient, if at all.