Case study

Sustainable energy services for isolated rural population through renewable mini-grid


Cape Verde

500.000 - 3M $






Provision of electricity to two isolated communities in Sant Antao through the installation of a 27kW photovoltaic mini-grid and 17km grid extention. 24h electricity access compared to the previous 6h of diesel generator. A special meter and tariff developed to match the PV technical caracteristics with loads. The system owned by the Municipality.

Project Description

Cape Verde has an electricity access rate of over 95%. Still some remote areas in the archipelago are not connected. The project, supported by the EU, offers two different solutions to provide electricity services to Tarrafal and Monte Trigo on Sant Antao Island: a 17km grid extension of the island main grid and a 27.3kW PV system within a new mini-grid. The solution makes it possible to have a 24h electricity access as compared to the 6 hours offered by the previously installed diesel generator. The 27,3 kW PV system supplies a 370kWh battery pack to provide electricity through 2 x 8kW inverters to 78 connections to households, commercial activities, local institutions, schools, and an ice making plant for fish preservation. The system offers 4 days autonomy and given the good solar irradiation, it is able to meet the energy demand throughout the year. A specific tariff structure based on the energy daily allowance principle (EDA) has been studied to meet the consumers’ needs and optimize the technical characteristic of PV system. The consumers pay a fixed flat rate tariff according to their agreed EDA. A smart meter gives visual information to customers to manage the loads and choose when it is most convenient to use electricity. The infrastructure is owned by the Municipality and is run by the local water concessionary. The system has been recently scaled up to 39.3 kW. The Cape Verde regulatory Authority is involved in tariff design to assure project long term sustainability.


274 people in Monte Trigo and 872 inTarrafal.


Two villages in Sant’Antao benefit from electricity access 24h a day. The project choses the best option combining traditional grid extention solution in Taraffal with innovative mini-grid development in Monte Trigo. The project serves as an electrification model in Cape Verde where the electrification rate is now >95%. Households, shops, institutions, school, kindergarden, dispensary, a telecomunication point for internet and TV, a tourist hostel and an ice making machine for fish preservation have reliable electricity service. The project has involved the beneficiaries in the design of the system and the PV panels have been mounted on a wooden pergola to provide shade to the local schoolyard. The project in Monte Trigo combines a sound technical design, a business model supported by an ad-hoc off-grid tariff scheme and a social approch consulting final consumers and stakeholders. The result is a sustainable infrastructure with bill payment rate at 100% and requests for new connections.

Business Model

Grid connected customers pay the national electricity tariff. A specific ownership and management solution has been tailored for the system in Monte Trigo. The infrastructure is owned by the Municipality and run by Aguas de Ponta Preta the water services concessionary. There are 4 tariff options, consumers pay a flat tariff. The tariff is cost reflective and covers long term system capital and running costs. The tariffs have been agreed by the community and approved by the Regulatory Authority.

Lessons Learnt

The sustainability of an off-grid system requires a specific tariff design to reflect the technical characteristic of a PV system connected with a battery pack. The principle of energy daily allowance has to be introduced, explained and agreed with beneficiaries. A flat tariff has been chosen to assure a constant cash flow to pay back the system. Different tariff options designed to meet the consumers’ needs. A smart meter has been programmed to assure that beneficiaries are not exceeding their daily allowance and the loads are constantly balanced with the available PV supply. An ice-making machine switches on when the system batteries are overcharged not to waste the available electricity.

Key Feature

The project has worked to offer the best available technical solutions to two different villages. The Monte Trigo system has been recently up-graded to 39.3kW to supply new connections, demonstrating its own capacity to grow. The project has complemented the technical design of the system with a strong sustainability strategy and a specific tariff scheme. The tariff structure is supported by the introduction of a smart meter, specifically programmed, able to balance the system supply with the consumers’ needs. The project offers off-grid systems innovative solutions to be implemented in similar contexts. In addition, the project has involved the local beneficiaries in the design of the system and in the analysis of their energy needs. The Municipality is the owner of the infrastructure and the local concessionary of water services manages the system. The Regulatory authority has been involved to approve the tariff structure, suggest solution and monitor the project result once over.

Other significant information

The capital cost of the PV system is estimated at 290,000€. The previous cost of diesel amounted at 10,400€/year, excluding the generator capital costs. The tariff has been designed to collect 14,000€/year to make the infrastructure sustainable and pay back PV running and capital costs. The equipment can be replaced within its lifespan. The service provides electricity 24h compared to 6h of diesel generator. The tariff is based on the energy daily allowance principle. The consumer can opt between 4 tariff options ranging from 825 to 2200Wh per day, with a monthly flat rate of 8,51 and 20,81€ respectively. A smart meter is able to reward low consumption with extra Wh and warn the customer once the available allowance has reached the 10% threshold. A visual signal indicates that the system is overcharged and the electricity can be used free of charge. A special tariff is designed for the ice making factory to promote the use of electricity when the system batteries are fully charged.

Main Donor

75% European Union, 25% Câmara Municipal do Porto Novo

Implementing Actor

Águas de Ponta Preta (Applicant), Municipality of Porto Novo (Public Administration) (Government)