He has also rendered consultant services for governments and regulatory authorities, international institutions, industrial associations and utilities in over 30 countries.

Through different stages, his research interests have included modeling, control and stability analysis of power systems; optimization of expansion and operation of power generation systems; transmission and distribution of electricity; and electricity sector regulation including issues related to transport, supply security, the design of regional wholesale markets and rates and, more recently, the sustainability of energy models and universal access to energy.

[3] In the late 1980s and early 1990s, his research was focused on the development of new algorithms and methodologies to support the operation and planning of electric power systems.

On the transmission side, he demonstrated why marginal prices fail to recover the total incurred network costs.

Currently he is Principal Investigator of the Comillas University - Massachusetts Institute of Technology Electricity Systems Program Archived 2014-01-03 at the Wayback Machine.

The group does research in LMICs, builds computational models for electrification planning, uses machine learning and remote sensing techniques for electricity demand and access rate estimation, and provides regulatory advice.

Pérez-Arriaga directs the Global Commission to End Energy Poverty, developing the Integrated Distribution Framework (IDF).