The COVID-19 pandemic and its countermeasures radically affected the energy sector. Within a matter of days, whole countries were into lockdown causing the largest energy impact of the last decades. This study explores the pandemic and its effects on the isolated power systems of Cape Verde, a small island-based developing state in Africa. Historical data from 2013 to 2021 is combined with ARIMA-based forecasting to estimate a COVID-free scenario. The results show how the country’s electricity demand suffered a 10% drop distributed among the islands proportionally to GDP per capita. The energy mix was unaffected, but the lower demand motivated 6% less emissions. The reliability of the system improved with respect previous years, but the transmission losses increased by 5% due to energy theft caused by the severe economic crisis suffered in the archipelago. In that sense, the impact on revenue and energy sector workers was quite limited. Furthermore, we also studied the effects of the pandemic in other energy related sectors such as water desalination and transport. The recovery started in the third quarter of 2020 as marked by the increased electricity demand, but also with the rapid growth of passengers and goods in the transport sector.