Design and Performance of a Multiple Compressor Solar Ice-maker PETROS AXAOPOULOS, MICHAEL P. THEODORIDIS Department of Energy Technology Technological Educational Institute of Athens Agiou Spyridona street, 12210 Egaleo, Athens GREECE Abstract: - This paper presents a solar photovoltaic powered ice-maker which operates without the use of batteries and is therefore environmentally friendly and may be used in truly autonomous applications in remote/isolated areas. The successful operation of the refrigeration compressors by the PV panels is ensured by the use of a dedicated controller, which provides easy startup, maximum power tracking and power management for the 4 compressors of the system. The prototype results have shown very good ice-making capability and reliable operation. Key-Words: Solar, ice-maker, batteryless 1 Introduction A solar photovoltaic refrigeration system, without battery, has been developed in the Renewable Energy Laboratory at the Technological Educational Institute of Athens. Our approach is to store the energy in ice and therefore to avoid the need for batteries, which are responsible for a significant portion of the capital cost and much of the maintenance cost. Additionally environmental pollution of lead might be expected from batteries, because their life cycle is limited. Deep cycle batteries are usually not produced in developing countries, making funding, purchasing and transporting them to remote sights difficult. In addition, funds may not be available to pay for the batteries when replacement is necessary. Recycling the used batteries is also very difficult and usually is rare. The new trend in solar operated or assisted thermal systems is to incorporate the use of a direct-current, variable-speed compressor. It has been shown in several research works that there occur reasons why compressors with capacity control offer distinct advantages over compressors with fixed capacity, especially concerning energy management and overall system efficiency [1-6]. The PV panel is connected directly to a capacity- modulated DC compressor via an efficient controller developed in our Laboratory. The advantage of using the developed controller is the improved utilization of the PV electric energy, achieved by modifying the compressor startup characteristics and exploiting the maximum power of the PV. In addition, the capacity modulation enables continuous efficient operation and also avoids the energy and mechanical costs of repeated start – stop cycles. The compressor is connected with a coolant circuit which is in thermal contact with the evaporator in the ice storage tank interior. The ice storage tank consists of an inoxydable insulated water tank with a submerged evaporator. The advantage of having an ice storage tank is the small required stores, 10-20% of the size compared to a chilled water store, and 30-50% compared to stores with eutectic salts. The developed unit can be used as a freezer and/or a refrigerator, and is suitable for a variety of application such as health, commercial and domestic purposes in areas where utility power is unavailable or utility line extensions would be too expensive. In the case where the unit will be used both for refrigerator and freezer, a secondary air- cooled loop can be added in a second compartment. The ability to store ice, instead of electrical energy in batteries, makes the proposed system a multifunction, sustainable and reliable cooling source both day and night without environmental risk. A conventional domestic refrigerator, with the same volume of refrigeration compartment, compared with the proposed system, takes 2 -3 times more power and consequently, requires more solar panels and moreover a large inverter and batteries.