DIRECT DRIVE SOLAR COOLERS

摘要

Many people in developing countries are living in areas without electricity from grid. Therefore, obtainingrna correct temperature storage of vaccines has been a challenge due to the lack of electricity to maintainrnthe recommended storage temperatures. Currently, most of the vaccines have to be stored at temperaturesrnbetween +2 ℃ and +8 ℃ at the service delivery points.rnFor many years, photovoltaic power has been used for vaccine refrigerators with a lead-acid battery tornstore electric energy and to provide the start-up current that drives the compressor. The problem with thisrntechnology is that the lifetime of the battery is short due to deep discharging of the battery during periodsrnwith low sunshine/irradiance.rnThe development of solar “direct drive” refrigerators started in 1999 at Danish Technological Institutern(DTI).rnIt was demonstrated that the energy capacity of ice produced by a compressor is at least of the samernmagnitude as the lead-acid battery. As of to date (February 2016), 24 direct-drive vaccine coolers fromrneight different manufacturers are listed on the WHO PQS website, with the technology being one of thernfastest growing technologies in the vaccine cold chain.rnThis paper endeavours to expound on the current status and discusses how the technology could be usedrnfor other purposes in the future.