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When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study

Tuesday, 4th of April 2017 Print

Abstract below; full text is at http://www.sciencedirect.com/science/article/pii/S0264410X17300555

 

Vaccine

Volume 35, Issue 17, 19 April 2017, Pages 2224–2228

When are solar refrigerators less costly than on-grid refrigerators: A simulation modeling study 

Available online 30 March 2017

 

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http://dx.doi.org/10.1016/j.vaccine.2016.11.103

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Under a Creative Commons license

  Open Access


Highlights

• WHO and Gavi recommend solar refrigerators where electricity is highly unreliable.

• We simulated electrical outages to identify conditions that favor solar devices.

• Solar refrigerators can provide value when there are relatively few one-day outages.

• Results suggest WHO and Gavi guidelines may be appropriate but conservative.


Abstract

Background

Gavi recommends solar refrigerators for vaccine storage in areas with less than eight hours of electricity per day, and WHO guidelines are more conservative. The question remains: Can solar refrigerators provide value where electrical outages are less frequent?

Methods

Using a HERMES-generated computational model of the Mozambique routine immunization supply chain, we simulated the use of solar versus electric mains-powered refrigerators (hereafter referred to as “electric refrigerators”) at different locations in the supply chain under various circumstances.

Results

At their current price premium, the annual cost of each solar refrigerator is 132% more than each electric refrigerator at the district level and 241% more at health facilities. Solar refrigerators provided savings over electric refrigerators when one-day electrical outages occurred more than five times per year at either the district level or the health facilities, even when the electric refrigerator holdover time exceeded the duration of the outage. Two-day outages occurring more than three times per year at the district level or more than twice per year at the health facilities also caused solar refrigerators to be cost saving. Lowering the annual cost of a solar refrigerator to 75% more than an electric refrigerator allowed solar refrigerators to be cost saving at either level when one-day outages occurred more than once per year, or when two-day outages occurred more than once per year at the district level or even once per year at the health facilities.

Conclusion

Our study supports WHO and Gavi guidelines. In fact, solar refrigerators may provide savings in total cost per dose administered over electrical refrigerators when electrical outages are less frequent. Our study identified the frequency and duration at which electrical outages need to occur for solar refrigerators to provide savings in total cost per dose administered over electric refrigerators at different solar refrigerator prices.

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