1. UNIT 2 SOLAR WATER HEATER AND SOLAR PHOTOVOLTAICS

2. SOLAR WATER HEATER

4. Salient features of SWH Around 60-80 0 C temperature can be attained depending on solar radiation,weather condition and solar collector efficiency. Only soft and potable water an be used. Stainless steel is used for large tanks and mild steel with anti corrosion coating inside are used for large tanks. SWH with 100-300 litres capacity is suitable for domestic purpose.

5. Fuel saving: A 100 litres capacity SWH can replace an electric geyser for residential use and saves 1500 units of electricity annually. 1unit = 1 kWh Environmental benefits SWH of 100 litres capacity can prevent emission of 1.5 tons of carbon di oxide per year. Life : 15-20 years

6. The payback period depends on site of installation,utilization pattern and fuel replaced. Payback period : 3-4 years when electricity is replaced 4-5 years when furnace oil is replaced 5-6 years when coal is replaced

7. SOLAR CELL OR PHOTOVOLTAIC CELL Energy conversion devices used to convert sunlight to electricity by use of photovoltaic effect are called solar cells. A number of cells are connected to form a module and a number of modules are connected to form a panel.

8. Conversion of solar to electrical energy

10. Equivalent circuit of solar cell An ideal solar cell may be modelled by a current source in parallel with a diode; in practice no solar cell is ideal, so a shunt resistance and a series resistance component are added to the model.diodeshunt

11. A Basic photovoltaic system for power generation

12. APPLICATIONS Agriculture Water-pumping installations (very important in developing Countries): systems of automatic irrigation.

13. Industry, Telecommunications & Public Services Cathode protection of gas, oil pipelines and other types of piping; provision of power in general, in particular for limited electric charges (in the order of a few kW) always in areas far from the grid or where power is unreliable (discontinuous electrical supply). Radio/television relay stations: telephone devices; stations for data surveying and transmission (meteorological, seismic, for levels of watercourses, indicating the presence of fires), often very useful for civil protection services. Lighting of streets, gardens and public transportation stops; street signalling.

14. Health Especially for refrigeration, very useful particularly in developing countries for the conservation of vaccines and blood. Residential Power provision (especially lighting) for houses and mountain refuges. Very significant applications of this type in developing countries: photovoltaic systems do not require special maintenance and are easy to install.