The greenest show in London right now is at Chisenhale, where Nicholas Mangan powers two films with solar panels on the gallery roof. In terms of power, itâ€™s a closed circuit.
But this isnâ€™t so muchÂ concern for the environment. The Australian artistâ€™s air miles mightÂ have scotchedÂ that. Itâ€™s aboutÂ the economy of sunlight on this troubled planet of ours.
Needless to say, we take the sun for granted. But we may still have a primal association between sacrifice and power. The Aztecs cut loose hearts; we invade and destabilise oil rich nations.
WeÂ donâ€™t have to list all the other murderous things we do in the name of energy. And Mangan makes no reference to them. Unless you count that looped video of a spinning Mexican ten-peso coin.
Like the sun, itâ€™s in perpetual motion. And it tees up a second channelÂ which includes footage from a Thermosolar plant in Southern Spain, and from a Tree Ring Research unit in Arizona.
This mainÂ film moves at a glacial pace. Itâ€™s as slow as our progress from day to night, but with interruptions like electromagnetic storms, which charge the room with excitement.
Knowing that the entire show was powered by the sun, this exhibition feels close to the centre of things. Looping around the sun along with the wide world beyond the gallery doors.
Mangan offers a glimpse of the effects that sun spots and solar flares could have on our behaviour, our crops and our markets. Could solar radiation trigger recession? Could it bring revolution?
Soviet-era biophysicist Alexander Chizhevsky thought so. His ideas about the dominion of the sun gained widespread acceptance in Russia, even ifÂ he got on the wrong sideÂ of the dominion of Stalin.
But how potent to think that past, present and future are written, not in our stars, but in just one celestial body: our nearest, and one at which we cannot look directly with the naked eye.
Ancient Lights is at Chisenhale Gallery until 30 August 2015