Unmanned helicopter lifting photovoltaic panels

What is an unmanned aerial vehicle (UAV)?

An unmanned aerial vehicle (UAV) is an aircraft that carries no human pilot and flies fully or partially autonomously . Massive efforts have been made to improve UAVs’ structure, working methodology, flying features, and navigation control .

Why are countries investing in solar unmanned aerial vehicles (UAVs)?

Many countries are increasing their investment in solar unmanned aerial vehicles (UAV) since the United States was reported to have created the first solar UAV called the Solar Challenger [ 2 ].

How to install photovoltaic cells on a UAV?

According to the methods of installing photovoltaic cells onboard, existing UAV solar energy harvesting can be divided into three types, including (a) mounting photovoltaic cells on UAV surfaces , (b) integrating photovoltaic cells into flapping wings of UAVs , and (c) mounting photovoltaic cells on other specific structures of UAVs .

What is the energy system of a solar UAV?

Energy system of a solar UAV comprises solar array, batteries and energy distribution system. Most of the existing solar UAVs have conventional multi-crystalline silicon solar cells. Advances in solar cells have resulted in thinner and lighter solar cells, but their welding onto the wing will also increase fragmentation rate.

What is the difference between solar and mechanical energy harvesting for UAVs?

Solar energy harvesting for UAVs mainly relies on photovoltaic cells and can reach watt-scale output power. In contrast, mechanical energy harvesting for UAVs can be further refined to wind-induced vibration and flapping wing motion whose output power is in the milliwatt scale.

Can solar energy harvesting power a UAV?

Among them, the total output power is often utilized as a benchmark in UAV energy harvesting. Generally, the harvested solar energy is larger than the harvested mechanical energy. Thus, solar energy harvesting may directly power the propeller and realize fully self-powered UAVs.