Solaris (solar power)

SOLARIS is a space-based solar power (SBSP) proposal of the European Space Agency (ESA).

The proposal calls for an in-orbit demonstration in approximately 2030, the first operational station in geostationary orbit by 2040 with subsequent stations added afterwards. Each modular solar panel would be almost one 1km wide, with ground receiving antennas about 6km wide each, generating up to a petawatt of power. The program is estimated to be able to supply between a 7th and a 3rd of Europe's current power demand, or 10% of its predicted demand by 2050.

At its November 2022 ministerial council meeting ESA sought funding of a three-year study into the proposal. Having successfully received that approval, in 2023 it commissioned Arthur D. Little and Thales Alenia Space Italy to independently develop "concept studies" for commercial-scale SBSP plants. The "economic, political, and technological feasibility" of continuing the project will be re-assessed at the next ministerial council, in 2025.

In preparation for the 2022 three-year study request, ESA separately commissioned consulting firms Frazer-Nash (UK) and Roland Berger (Germany) assess the potential of the scheme to support the European policy goal of a net-zero carbon economy by 2050:

Criticisms of SOLARIS and other SBSP schemes, even by their proponents, include challenges in at least three areas: whether it is possible to build the technology and logistics required to launch, remotely-assemble, and operate massive satellites; the "policy implications associated with beaming power from space"; and whether it is affordable. Important factors in increasing the feasibility of the proposal has been the recent rapidly decrease in launch cost, as well as advances in robotic manufacturing and wireless energy transfer. A 2022 tests in Germany for the SOLARIS program demonstrated the ability to wirelessly beam power across a distance of 36m, however there is "still a way to go" before it is possible to achieve the same from the distance of geostationary orbit. Earlier in the same year, both the China Academy of Space Technology and the NASA Office of Technology, Policy and Strategy had each approved studies and tests in components of similar schemes.