The obvious choice would be solar, except for the fact that at this time of year we only get around 6 hours of daylight in Copenhagen. Winter solstice was yesterday.<p>Wind might work, a windmill for boats might be able to give us the power needed. At least it would extend the battery time. Only problem with that is that they&#x27;re quite expensive, and we didn&#x27;t have much of a budget to begin with.<p>Maybe next year... There were so many things we&#x27;d like to have done, but didn&#x27;t find the time and money for. One of them was an app or a dedicated webpage where you control the lights on the tree. Maybe even some kind of game where you play some game on the tree against other players.<p>Lots of possibilities, but limited time and money...