  Recent global events emphasize the importance of a reliable energy supply.
One way to increase energy supply security is through decentralized off-grid
renewable energy systems, for which a growing number of case studies are
researched. This review gives a global overview of the levelized cost of
electricity (LCOE) for these autonomous energy systems, which range from 0.03
\$_{2021}/kWh to over 1.00 \$_{2021}/kWh worldwide. The average LCOEs for 100%
renewable energy systems have decreased by 9% annually between 2016 and 2021
from 0.54 \$_{2021}/kWh to 0.29 \$_{2021}/kWh, presumably due to cost
reductions in renewable energy and storage technologies. Furthermore, we
identify and discuss seven key reasons why LCOEs are frequently overestimated
or underestimated in literature, and how this can be prevented in the future.
Our overview can be employed to verify findings on off-grid systems, to assess
where these systems might be deployed and how costs evolve.
