SOLARCHILL - A SOLAR PV REFRIGERATOR WITHOUT BATTERY

(Given by: Henrik Pedersen, Soren Poulsen & Ivan Katic)

ABSTRACT

A solar powered refrigerator (Solar Chill) has been developed in an international project involving Greenpeace International, GTZ, UNICEF, and UNEP, WHO, industrial partners and Danish Technological Institute. The refrigerator is able to operate directly on solar PV panels, without battery or additional electronics, and is therefore suitable for locations where little maintenance and reliable operation is mandatory. The main objective of the Solar Chill Project is to help deliver vaccines and refrigeration to the rural poor. To achieve this objective, the Solar Chill Project developed — and plans to make freely available a versatile refrigeration technology that is environmentally sound, technologically reliable, and affordable. Solar Chill does not use any fluorocarbons in its cooling system or in the insulation.

KEYWORDS

Applications and loads, cost reduction, demand-side, devices, PV system, refrigeration, reliability, standalone systems, storage, sustainable.

LITERATURE REVIEW

The unique feature of Solar Chill is that energy is stored in ice instead of in batteries. An ice compartment keeps the cabinet at desired temperatures during the night. Solar Chill is made from mass produced standard components, which results in a favourable cost compared with other vaccine solar refrigerators. The Solar Chill has undergone intensive laboratory tests in Denmark, proving that it fulfils the objectives set for the project. In addition, a field test programme in three different developing countries is ongoing with the aim to gather practical experience from health clinics. For domestic and small business applications, another type of solar refrigerator is under development. This is an upright type, suitable for cool storage of food and beverages in areas where grid power is non-existent or unstable. The market potential for this type is thus present in industrialised countries as well as in countries under development. The paper describes the product development, possible Solar Chill applications and experience with the two types of solar refrigerators, as well as results from the laboratory and field test.

The reason for choosing energy storage in ice was to avoid a lead battery for energy storage. Lead batteries tend to deteriorate, especially in hot climates, or they are misused for other purposes. This makes it necessary to install a new battery after a couple of years, and has in practice been an obstacle for the use of solar powered refrigerators. In addition to that some pollution of lead might be expected from the used batteries.

REFERENCES

I. PV-POWERED VACCINE COOLER WITH ICE PACKS AS POWER BACKUP Soren Gundtoft, Danish Technological Institute, 2003

II. Project flyer: http://www.uneptie.org/ozonaction/library/tech/solar chill.pdfIII. Compressor data sheet: http://www.danfoss.com/compressors/pdf/product_ne

ws/bd_solar_09-03_cx30e302.pdf

FRAMING SYSTEMS FOR SOLAR PANELS

(Given By: Peter Stuart Erling)

ABSTRACT

The invention relates generally to framing systems and more particularly is concerned with systems adapted to mount panels or laminates in an array on a supporting roof structure of a building exemplified with the mounting of solar electric photovoltaic (PV) panels. The framing system described uses extruded elongate elements with a sealing element to frame the PV panel as a weatherproof PV solar roof tile. Individual frame element profiles effectively embody the PV building integration, (BiPV) or mounting method, of the solar tile within the frame itself. Only a few additional flashing components are needed to complete the PV tile array as part of the roof, or with minor variations, as a PV wall cladding. Full BiPV panel mounting methods show potential to be used for co-generation (PV/T) of solar thermal energy capture in buildings.

The batten support structures of the solar tile permit variation in roof batten spacing to be tolerated in retro-fit situations make trafficable roof with the tiles possible and provide long term weather-ability as a building element through moisture reduction by air flow and smaller surface contact. Draining of internal roof condensate from the back of the tiles to the exterior is another feature of the frame system described.

KEYWORDS

Plastic, Thermal conductor, Aluminium material, Thermal energy, Solar electric photovoltaic (PV), Internal roof.

LITERATURE REVIEW

It is common for solar panel frame materials to be made from aluminium material that is surface treated against corrosion for the arduous climatic exposure it has to endure however aluminium has a significant embodied energy in its life cycle therefore a framing system that can use lower cost and lower embodied energy materials like plastics but that can still endure a long service life is desirable. Plastics also can provide better thermal insulation between outside and inside conditions of a building when used in the framing of glass than aluminium, which is a good conductor of thermal energy unlike plastics that are poor thermal conductors. It would therefore be beneficial to devise systems which can utilise the advantage of plastics in combination with a lower proportional use of surface treated aluminium but retaining the desirable and proven long term weather endurance of aluminium in the solar tile frame system.

In the field of solar PV panels, proposals have been made to form the PV panel to have the general characteristics of a roofing tile so that the PV laminate may be integrated into a roof, commonly but not exclusively, a tile roof. An alternative approach is to have a panel which is adapted to be mounted over a roof However; important considerations to the design and development of PV panels are the ability of the panels to be effectively integrated architecturally into a roof design. With in-roof integrated panels there is also known to be a greater opportunity to beneficially capture solar thermal energy in addition to PV electrical energy to use within the building on which the PV tiles are installed, a field of solar energy development known as PV/Thermal or PV/T. Where the panels take the place of conventional roofing elements such as tiles or metal systems, reliable and convenient mounting within the roof and effective weather sealing is most important.

EXPERIMENTAL INVESTIGATION ON A THERMO-ELECTRIC REFRIGERATOR DRIVEN BY SOLAR CELLS

(Given by: R.Z. Wang, L. Ni)

ABSTRACT

Experimental investigation and relevant analysis on a solar cell driven, thermoelectric refrigerator has been conducted. To make the device portable, daytime use and nighttime’s use of the refrigerator are treated in different ways. Solar cells are applied to power the refrigerator in the day. Storage battery, assisted by an a.c. rectifier, is used to provide electric energy in the night and in cloudy or rainy days. Experiment results demonstrate that the unit can maintain the temperature in the refrigerator at 5–10 °C, and have a COP about 0.3. It is expected that the refrigerator would be potential for cold storage of vaccine, foodstuffs and drink in remote area or outdoor applications where electric power supply is absent.

KEYWORDS

Thermoelectric refrigeration; Solar cells; Insulation rate; cooling production

LITERATURE REVIEW

A solar panel is a photovoltaic module which is built up by a certain combination of solar cells. The material of the solar cell for the solar panel used in this research project is multi-crystalline silicon. A solar panel functions by directly converting the solar radiation into direct current electricity. In this project, a combination of four solar panels is applied to build a solar array, in which two units are configured in series and another two in parallel. Such combination is essential for efficiently charging the lead acid batteries and then operates the refrigerator. Each of the solar panels with the specifications of 17.5V (maximum power point voltage), 5.7A (maximum power point current), and 100W (nominal peak voltage) is used in this PV system.

REFERENCES

Dai, Y.J., Wang, R.Z., Ni, L. (2003). Experimental investigation on a thermoelectric refrigerator driven by solar cells.

Kaushika, N.D., Gautam, N.K., Kaushik, K. (2005). Simulation model for sizing of stand-alone solar PV system with interconnected array.

Min, G., Rowe, D.M. (2006) Experimental evaluation of prototype thermoelectric domestic-refrigerator.

PERFORMANCE ANALYSIS OF A SOLAR PHOTOVOLTAIC OPERATED DOMESTIC REFRIGERATOR

(Given by: R. Saidur, H.H. Masjuki, M. Hasanuzzaman, T.M.I. Mahlia, C.Y. Tan, J.K. Ooi and P.H. Yoon)

ABSTRACT

This paper describes the fabrication, experimentation and simulation stages of converting a 165 l domestic electric refrigerator to a solar powered one. A conventional domestic refrigerator was chosen for this purpose and was redesigned by adding battery bank, inverter and transformer, and powered by solar photovoltaic (SPV) panels. Various performance tests were carried out to study the performance of the system. The coefficient of performance (COP) was observed to decrease with time from morning to afternoon and a maximum COP of 2.102 was observed at 7 AM. Simulations regarding economic feasibility of the system for the climatic conditions of Jaipur city (India) were also carried out using RET Screen 4. It was observed that the system can only be economically viable with carbon trading option taken into account, and an initial subsidy or a reduction in the component costs – mainly SPV panels and battery bank.

KEYWORDS

Thermoelectric refrigeration, Solar powered refrigerator, photovoltaic system

LITERATURE REVIEW

A thermoelectric refrigerator which is developed in standalone photovoltaic system for domestic usage has been presented in this paper. The photovoltaic sizing required for efficiently running the thermoelectric refrigerator with energy consumption 520Wh is including 4 solar modules of 5.7A, 17.5V and100W; 4 lead acid batteries of 12V and 100Ah, a solar charge controller of 12A and 24V; and an inverter of 24V and 150W. For maximizing the electricity generation, the photovoltaic array should be oriented at 15 degrees from horizontal and is installed facing south. The peak power produced by the photovoltaic array is 230 watt. It has been shown that the battery bank is able to act as a backup energy supplier for 3 autonomous days.

The thermoelectric refrigerator can maintain the temperature in refrigerated space at 1~7 o C and at averagely 4o C. The warm up time for the cooling temperature to increase back to ambient temperature after being switched off is about 4 hours. Instead of using vapour compression refrigerator, thermoelectric refrigerator is applied due to its lower starting

power, environmental friendliness, and noiselessness. The performance of this refrigerator can be improved by adding insulation to the refrigerator’s body as well as improving its heat exchanger efficiency. It is recommended for not opening the photovoltaic driven thermoelectric refrigerator more than 30 seconds each time.

A solar charge controller is applied in this solar powered domestic refrigerator system. It is installed between the solar array and the battery bank. A solar charge controller’s primary function is to protect the battery bank from overcharging and under discharging that will permanently damage the battery bank. It has the specification of 12A (maximum charge & load current) and 24V (system voltage).

RESEARCH QUESTIONS

1. Do we have any Solar Energy technology installed in your home?

2. How do solar photovoltaic panels work, and are they really as efficient as everyone says?

3. What are building-integrated photovoltaic and are they a legitimate alternative to photovoltaic panels?

4. How much space will a solar photovoltaic system require?

5. Do solar energy systems need a lot of maintenance?

6. How much will a solar photovoltaic system cost me and how long will it take for it to pay for itself through energy cost savings?

7. How long do photovoltaic (PV) systems last?

8. What's the difference between PV and other solar energy technologies?

9. Can I use photovoltaic (PV) to power my home?

10. How much does a solar energy system cost, and how much will I save on utility bills?