The parity paper is out
My 2022 undergraduate thesis asked a simple question: can a solar-powered multirotor ever harvest as much energy as it consumes in flight? Four years later, that question has a citable answer. The paper, "Solar charge-consumption parity in multirotor UAVs: a reproducible simulation study," is published as a preprint on engrXiv: doi.org/10.31224/8404. All code and figures are open and archived on Zenodo, so anyone can rerun every number.
The answer is no, and it is not close. A 3 kg quadcopter with a square metre of panel harvests 1,567 Wh against 6,613 Wh consumed over a Dhaka solstice day, and the parity solver shows even tripled sunlight cannot close the gap. It is a negative result, and negative results are worth publishing when they are honest: this one tells you exactly how far solar multirotors are from self-sustaining flight, and which levers (panel area, consumption, duty cycle) actually move the needle.
What is next: a second version with three independent validations, the sky model checked against PVGIS satellite data, the AtlantikSolar 81-hour flight reproduced with the same energy model, and hover power checked against commercial quadcopters. Then a journal submission. The honest numbers stay; only the confidence in them grows.
Update, 14 October 2026: the three validations are complete and the propulsion model has been recalibrated against real hover data. The second version of the paper is being rebuilt toward journal submission.