UNIT 2
SOLAR WATER HEATER
AND
SOLAR PHOTOVOLTAICS
SOLAR WATER HEATER
SOLAR WATER HEATER
Salient features of SWH
• Around 60-800 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.
• 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
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
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.
Conversion of solar to electrical energy
Conversion of solar to electrical energy
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.
A Basic photovoltaic system for power generation
APPLICATIONS
• Agriculture
Water-pumping
installations (very
important in
developing Countries):
systems of automatic
irrigation.
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.
• 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.