| |
|
| Solar
Water Heater Basics |
 |
What
is Solar Hot water System ? |
|
|
What
is Solar Collector ? |
|
|
How
does the Solar Collector work? |
|
|
Why
do the Solar Collectors face the south direction? |
|
|
Why
is the collector kept in an inclined position
? |
|
|
How
is the Solar Hot Water System specified ? What
is LPD ? |
|
|
How
is the solar system capacity determined for a
given requirement ? |
|
|
What
is forced flow (FF) System and what is Thermosyphon
System (TS)? |
|
|
What
is FTC ? |
|
| Solar
Water Heater Performance |
|
|
Is
it possible to get hot water early in morning
? |
TOP |
|
Can
we get hot water all 24 hours of the day? |
|
|
Will
the Solar Water heater deliver hot water during
monsoon? |
|
|
Are
temperatures similar to electronic geysers possible
using Solar Geysers? |
|
|
Can
higher temperatures be obtained? And can any
extra demand for hot water be met, especially
when guests are visiting? |
|
| Solar
Water Heater Economics |
|
|
What
kind of maintenance is required? |
|
|
What
is the estimated life of a Solar Hot Water System? |
|
|
Is
it possible to integrate the Solar Hot water
system into the design of my house? |
| |
What
is Solar Hot water System ?
Solar
Hot Water System utilizes solar energy to
heat water to the desired temprature. The
heated water may be stored in insulated tanks
for use in the morning or used during day
time. The complete Solar Hot Water Tank,
Circulation pump, Temperature Controller
for the pump and instrumentation to measure
water flow rates, quantity of water used,
temperatures of hot and cold water, electrical
energy consumed and cumulative time for which
circulation pump runs. A typical Solar Hot
Water System is schamatically shown in
|
|
How
does the Solar Collector work?
The
sun-ray pass through the transparent glass
and strike on the black surface of the absorber.
The black coating on the absorber convert
the radiation energy of sun-rays into heat.
This heat is conducted to the tubes by fin
which is made of copper or high conductivity
material. The tube carry water which receives
heat from the tube and becomes hot. To reduce
the heat losses and thereby increase the
efficiency of the solar collector, thermal
insulation is provided at the back of the
absorber.
The glass covers serves two main purpose. It reduces the effect of wind and heat
losses, and protects the black coating on the absorber from the effects of weather,
rain etc
|
|
Why
do the Solar Collectors face the south direction?
India
in northern hemisphere, therefore maximum sunshine
is captured by a surface facing South direction over
the whole year. This is particularly so during winter.
|
|
Why
is the collector kept in an inclined position
?
For maximum efficiency, the sun-rays should Strike the collector at right angles.
For water heating applications, maximum output is required during winter when
the sun is at lower altitudes. For maximum output therefore, the collectors should
face south direction and be kept at an inclination equal to latitude of the place,
which is around +15 to +20 degrees.
|
|
How
is the Solar Hot Water System specified ?
What is LPD ?
The capacity of a solar hot water system is specified is LPD. It is a short form
for Liters Per Day. The intensity of Solar radiation varies through out the day,
hence capacity cannot be specified in terms of hourly output.
|
|
How
is the solar system capacity determined for
a given requirement ?
To determine the capacity of the solar system required. first find out the hot
water consumed during the day as well as during night, over 24 hours during winter
season. the capacity of the solar hot water system in LPD should be equal to
or grater than the hot water consumed during the 24 hours.
|
|
What
is forced flow (FF) System and what is Thermosyphon
System (TS)?
The water heated by the solar collector needs to be transferred to the insulated
storage tank. when the heated water in transferred by means of a pump ( usually
for large capacity systems ) it is called forced flow (FF) system. Most industrial
systems are FF systems.
When circulation of heated water from collector to the storage tank is by means
of the density difference between hot and clod water , it is called thermosyphon
(TS) system. In this system the storage tank storage tank must be placed above
the collector.
|
|
What
is FTC ?
FTC means Fixed Temperature Control.
The operation of the circulation pump of forced flow system needs to be controlled
to avoid pumping of cold water into the hot water storage tank. In FTC control,
it is achieved by monitoring the temperature at the outlet of the collector.
The pump is switched ON only when the outlet temperature is higher than the SET
temperature. If the temperature falls below the SET temperature, the pump is
automatically switched OFF.
|
|
Is
it possible to get hot water early in morning
?
Yes. The cold water is heated during the day & it is stored in an specially
insulated storage tank all night, this insulation prevents the water from losing
heat, so that you have piping hot water the next morning. |
|
Can
we get hot water all 24 hours of the day?
Yes ! The advantage of the solar hot water geyser is that you get hot water any
time of the day or night, and irrespective of the fact whether there is electricity
or not! This is true, but is limited to system capacity- the maximum quantity
of hot water that can be utilised in a day will depend on the system capacity.
If you withdraw more water than the rated capacity, then the water might not
be hot enough.
|
|
What
happens during the monsoon season when it
is raining and there is less sunshine?
India recieves a clear and good sunshine almost throughout the year as it is
close to the tropics. Even during winter the Solar Geyser works extremely well
as it has been especially designed for maximum efficiency during the winter season.
However during the monsoon season, depending on the hours of sun shine available,
you may get varying degrees of warm water. PROSUN offers an optional electric
heater installed within the solar geyser, to heat water during the rainy season,
if you desire hotter water.
|
|
Are
temperatures similar to electronic geysers
possible using Solar Geysers?
Electric geysers are usually set to 60 C, so you need to mix some cold water
in geyser outlet water to make it suitable for bathing. It is almost the same
with domestic solar water heating systems, the water temperature are generally
about 60 C with an variation of about +/- 5 C, depending on season. So the Solar
Geyser can adequately replace the electric geyser, plus save money on the electric
bill.
|
|
Can
higher temperatures be obtained?
Yes. Much higher temperatures are possible with the Solar Geyser, though the
use is restricted to the industrial sector. PROSUN has designed many industrial
systems with high temperatures such as 95 C for provided boiler feedwater.
|
|
What
kind of maintenance is required?
Most domestic Solar Geysers dont require a lot
of maintenance, as there are no moving parts
in the solar geyser. The only maintenance needed
is cleaning of the glass once a month for best
results.And if you live in a hard water area,
the descaling process once every year is recommended.
For
Industrial systems, the pumps need to be inspected
at frequent intervals, check for scaling and
choking periodically and replacement of some
parts of the control panel, as and when required.
|
|
What
is the estimated life of a Solar Hot Water
System?
PROSUN uses all Aluminium, Stainless Steel or Copper parts for the Solar Hot
water systems manufactured by us, hence they usually last for about 15-20 years.
Some maintenance may required periodically to get maximum efficiency like electric
back-up etc. may need replacement. We have some of our very first Solar Geysers
(manufactured 15-18 years ago!) still functioning properly to the great satisfaction
of our customers.
|
|
Is
it possible to integrate the Solar Hot water
system into the design of my house?
Yes! The system can be designed into your house to fit unobtrusively on to a
sloping roof, with a storage tank concealed, etc. This is best done, with the
active involvement of your architect with our representative at the design stage
itself, any modifications or changes later on are difficult to incorporate.
|
|
