Solar PV fridge

Vaccines for diseases such as polio, tuberculosis and diphtheria need to be kept cool, from the point of manufacture until final use.

In the heat of north east Nigeria, they can deteriorate rapidly. Standard refrigerators are of little use in remote areas where the mains supply is unreliable or non-existent. KXN provides vaccine refrigerators powered by solar photovoltaic (PV) modules, to keep vaccines cool.

I gave birth to twins at around 9.15 this morning. After being born, I’m immunising them. I’m very happy. May God bless the twins for me.

New mother

The north-east of Nigeria is one of the few regions in the world where polio has still not been eradicated. Vaccination is critical to any eradication programme. However, vaccines must be kept at low temperatures right up to the point of use, if they are to be effective. But in rural Nigeria, the electricity supply needed to run a refrigerator is not reliable, and often not even available in rural areas.

KXN Nigeria, a local company, knew that vaccine refrigerators powered by solar photovoltaic (PV) modules could provide 24 hour reliability. With funding from the government and Rotary International, by 2009 they had installed 767 vaccine refrigeration systems, enabling immunisation services for a population of about 4.6 million people. 

The refrigeration systems are not cheap at about US$11,000 each including the PV modules and rechargeable batteries. But as they provide life-protecting reliability, and as each one holds over US$5,400 worth of vaccines when full, the cost is not hard to justify. And in addition to polio vaccines, the fridges are used for tuberculosis and diphtheria vaccines.

In common with many such projects the innovation and manufacturing are half the solution. A supply of trained local technicians is critical to the installation and maintenance of the fridges. Working with the University of Maiduguri in Borno State and with BP Solar, KXN trained technicians to install and maintain both PV refrigerators and other PV systems, so widening the knowledge needed to back-up the project. 

Key points

  • 240 Wp of PV modules power each vaccine refrigerator, keeping the battery charged for 24-hour cooling. 
  • Heavy insulation means the refrigerators need little electricity to operate and can keep cool despite high ambient temperatures.  
  • KXN worked with the University of Maiduguri and BP Solar to train technicians to install and maintain both PV refrigerators and other PV systems. 
  • A typical PV vaccine refrigeration system costs about US$10,800. Paid for by the National Programme for Immunisation and Rotary International, and installed free in remote health centres. 
  • Between 2002 and 2004, 189 vaccine refrigerator systems were installed across the north east of Nigeria, benefitting some 90 villages. 
  • Each  system serves a population of typically 6,000 people, so a total of 1.1 million people gained access to vaccination. 
  • Vaccine refrigerators powered by PV are more reliable than ones run on diesel or kerosene. 
  • Programme has generated local employment: by 2005, 12 people trained as solar technicians to install and maintain refrigeration systems and to build on this to become solar entrepreneurs. Others employed for administration, warehousing and assembly.

Background

Diseases such as polio, tuberculosis and diphtheria can be controlled and eventually eliminated with vaccines. However, unless vaccines are kept cool (at around 3°C) from the point of manufacture until final use, they deteriorate rapidly. In remote health centres in north-east Nigeria, standard refrigerators running off mains electricity are of little use because the mains supply is unreliable or simply non-existent. Diesel generators need a reliable supply of fuel which cannot be guaranteed in remote areas. Kerosene absorption refrigerators can be used, but also require a reliable supply of fuel.

KXN provides a vaccine refrigeration system using photovoltaic (PV) modules to supply power, with lead-acid batteries for electricity storage, enabling continuous operation night and day. . 

The organisation

KXN Nigeria is a private company established in 1999 by Anthony Ighodaro and Knowledge Exchange Network Ltd of the UK. It uses solar technology to deliver dependable energy and improve living standards in Nigeria, distributing, assembling and maintaining PV systems. In 2010, it had a turnover of US$2.7 million, employed 8 people and had a board of 6 directors.

Villagers in North East Nigeria.

The technology

How does it work? 

The system supplied and installed by KXN consists of a vaccine refrigerator and freezer, with PV modules, batteries, charge controller and associated cabling. 240 Wp of PV modules generate electricity from sunlight and keep the batteries charged for 24-hour cooling. The PV modules are connected to the battery via a charge controller which protects the battery from being over-charged or over-discharged, and provides a constant DC operating voltage for the refrigerator. Heavy insulation means the refrigerators need little electricity to operate and can keep cool despite high ambient temperatures. 

How much does it cost and how do users pay? 

US$1 = 133 NGN (Nigerian Naira) [September 2006]

A typical PV vaccine refrigeration system costs about US$10,800 (1.4 million NGN). Although this is high, the system holds over US$5,400 worth of vaccines when full, so the investment is well justified.

167 of the 189 systems installed by KXN were paid for by the National Programme for Immunisation, and installed free in remote health centres as part of the national campaign to eradicate polio. This represented about 20% of the installations under the National Programme, with other installers working in different states. The remaining 22 systems were funded by Rotary International Nigeria.

The technology in more detail

One type of vaccine refrigerator used is the RFVB-134a, manufactured by Sun Frost. In this model, the vaccines are surrounded by 100 to 150 mm of polyurethane foam insulation, which allows the PV system to keep them at 3°C, even when the ambient temperature rises to 43°C. Despite its small size, the refrigerator is large enough to hold 72,000 doses of polio vaccine. A separate freezer compartment can produce and hold up to 12 kg of ice. This can be transferred to the refrigerator section to keep the vaccines chilled for up to nine days, if the battery has become completely discharged. The high insulation and efficient compressor mean that the refrigerator consumes only 0.3 kWh of electricity per day when operating at an ambient temperature of 32°C, if no ice is being made. An additional 0.2 kWh is needed per kg of ice produced. Power is supplied at 12 or 24 V DC from a lead-acid solar battery. These batteries are designed to withstand deep cycles of discharging and charging which would destroy a standard car battery in a few months. 

KXN also installs small solar-homesystems that supply off-grid power to satellite phones, laptop computers, digital cameras and data loggers used by the field technicians, and larger systems in the cities. The system components are imported from Europe, Japan and the USA and are assembled in Nigeria.

How is it maintained? 

PV vaccine refrigerators need to be installed correctly, and health centre staff need to know how to use them. KXN knew that there was a very limited supply of PV technicians in remote areas of Nigeria, but also recognised that maintenance of vaccine refrigerators would not provide sufficient work for a PV technician to run a viable business. KXN therefore worked with the University of Maiduguri in Borno State and with BP Solar to train technicians to install and maintain both PV refrigerators and other PV systems. 

Benefits

Between 2002 and 2004, KXN installed 189 vaccine refrigerator systems in 90 villages across the north east of Nigeria. A single vaccine refrigerator serves a population of about 6,000 people, so about 1.1 million people in total now have access to vaccination.

Social and health benefits 

The north-east of Nigeria is one of the few regions in the world where polio has still not been eradicated. The main motivation for the installation of PV vaccine refrigerators was to enable a programme of polio vaccination in remote areas, but the programme also provides immunisation against other dangerous diseases such as tuberculosis, diphtheria and whooping cough. 

The main benefit of using solar PV rather than diesel or kerosene to run vaccine refrigerators is the greater reliability, and the WHO recommends PV as the power source for remote areas. However, solar powered refrigerators also avoid the noise and fumes of diesel generators and pollution from diesel or kerosene spills. 

Employment benefits 

Twelve people were trained as solar technicians to install and maintain the refrigeration systems. KXN helped three of these installers to build on their experience and become solar entrepreneurs, generating additional income by selling commercial PV services such as solar home systems, battery charging and water pumping. Two local people have been employed on a casual basis for administration and warehousing and local people assemble the systems from imported components.

Update: what happened next?

By 2009, KXN had installed 767 vaccine refrigeration systems in Nigeria, a significant increase on the 189 installed by the end of 2004.  Although KXN has experienced slow growth in the sale of solar home systems, the sale of PV modules and large scale PV systems to the private sector in Nigeria is thriving.