Solar Fridge

Designing a solar-powered refrigerator to store vaccines

Project Background

Mission

More than 1.5 million people die from vaccine-preventable illnesses each year due to limited access to vaccines. Areas with warm climates and limited electricity access are particularly impacted as vaccines need to be kept at a certain temperature range to remain viable.

Therefore, there is a need to develop a sustainable and cost-effective vaccine storage system to maintain vaccine viability during power shut-offs.

Community Partner

During the summer of 2017, our team performed a problem definition trip with our community partners in Rincon Claro, a small village in the Dominican Republic. We learned that their local clinic does not have access to reliable on-site vaccine storage, making the ultimate goal of Solar Fridge a perfect solution. We also visited neighboring communities and concluded vaccine storage is an overarching problem in this region. This trip helped Solar Fridge establish a long-term connection with Dr. Jorge Ramirez, the doctor of Rincon Claro. After making promising progress with our prototype, Solar Fridge traveled again to Rincon Claro in May 2024 to test our prototype and receive feedback on our developments.

Design Requirements

User Need

Design Requirement

Design Specification

Vaccines viability is maintained so there is no waste

Maintain vaccine viability during power shut-off

Uniform 2°C and 8°C [1] temperature range for 72+ hour holdover time [2] at maximal 43°C ambient temperature

Fridge must be affordable for all clinics

Cost effectiveness

Manufacturing + shipping costs <$900

Nurses/Doctors need to easily see internal temperatures of fridge

Provide feedback and alerts

Indicator for temperature excursions outside 2°C and 8°C

Displays present, max, min temperatures

Stores past temperatures with 1 measurement/30 min [3]

Follow safe storage conditions for vaccine viability

Storability and organization

Vaccines stores 2-3 inches for unit boundaries [3]

Storage of 50+ vaccines

Separation for 9+ vaccine types [4]

Project History

The origins of Solar Fridge began as a Senior design project in 2008 and transitioned into an interdisciplinary team within M-HEAL a few years later. There have been several iterations of the prototype since the project’s creation. Ultimately, the team has focused on creating a solar-powered fridge, utilizing solar panels and a rechargeable battery.

By 2023, our two engineering subteams—Temperature Control and Electrical—created a combined low-fidelity prototype based on extensive brainstorming and material research. The Temperature Control subteam focused on constructing a highly insulated and portable cooler while the Electrical subteam made a cooling system using a Peltier Device and PID controller. Each of these subsystems was tested individually and adjusted according to the results.

During this time, our Business subteam developed a new website platform for Solar Fridge and guided the team to the Michigan Business Challenge Finals, a competition for new business proposals.

From Fall 2023 to the present, the engineering subteams have worked on creating a new high-fidelity prototype based on the testing results of our Winter 2023 low-fidelity prototype. The Temperature Control subteam purchased a larger, more transportable cooler and integrated upgraded insulation materials. The Electrical subteam converted the main power source of the cooler to solar panels. We continue to make design upgrades, test new changes, and implement feedback from our trip to Rincon Claro in May 2024. Through this time, the Business subteam led us through the semifinals of the Rice360 global health design competition, raised travel funds, and planned our international trip to the Dominican Republic for testing of our high-fidelity prototype.

Leads

Maggie Robbins (she/her)
Solar Fridge Co-Lead
Junior: Chemical Engineering

References

[1] NSF 456 vaccine refrigerators and freezers testing. UL. (n.d.). Retrieved December 1, 2021, from https://www.ul.com/services/nsf-456-vaccine-refrigerators-and-freezers-testing.

[2] E. Maritz, personal communication, October 3, 2021

[3] Centers for Disease Control and Prevention. (2019, July 11). Vaccines storage and handling toolkit. Centers for Disease Control and Prevention. Retrieved December 1, 2021, from https://www.cdc.gov/vaccines/hcp/admin/storage/toolkit/index.html.

[4] Dr. Jorge Ramirez, personal communication, November 13, 2021

[5] “How to design a peltier module system,” CUI Devices, 02-Apr-2019. [Online]. Available: https://www.cuidevices.com/blog/how-to-design-a-peltier-module-system. [Accessed: 06-Apr-2023].