FAQS
SOME QUESTIONS ABOUT SOLAR WATER HEATING NOW ANSWERED.

(1) What size of system do i need?
      The size of Solar Water Heating System depends on two factors.
      (a) the total water requirement in a whole day (24 hours.)
      (b) the temperature to which it is to be heated i.e. 60 °C or 80 °C(celcius). For most domestic and other cleaning applications 60 °C water is preferable. Certain industries, laboratories etc. may require 80 °C water.
Our "ATASH" Flat Plate Solar Collector with its Black Chrome Advantage can deliver 125 litres per day (LPD) at 60 °C. As a general thumb rule for domestic purposes a system of 125 LPD (60 °C) i.e. with one flat plate collector is good enough for a family of 4 people. A family of 8 would require a 250 LPD (60 °C) system and so on. Commercial establishments would have to estimate their daily water requirement usage to calculate the size of the system.

We are manufacturing a better "ATASH" Solar Water Heating System. We expect our "ATASH" Solar Water Heating System to last atleast 20-25 years.

(2) Suppose I need 1000 LPD at 60 °C?
As each "ATASH" Flat Plate Solar Collector gives 125 LPD at 60 °C you would require a system with 8 such collectors coupled to an insulated storage tank of 1000 litres.

(3) And suppose I need 1000 LPD at 80 °C?
As a thumb rule for a 80 °C system about 1 1/2 times the collectors required for a 60 °C need to be installed. Hence you would require 12 "ATASH" Flat Plate Solar Collector and coupled to a 1000 liters per day storage tank. However, this is subject to location and intensity of Solar Radiation.

(4) Is the electric pump needed to circulate the water?
For systems upto 3000 liters per day (60 °C) no pump is required. The water circulates on its own by the thermosyphon principle. For systems of larger capacities, a small pump and elactical controls are needed.

(5) What is the maintenance required?
For small systems running on the thermosphon principle practically no maintenance is required. A periodic cleaning of the top glass is however necessary. For larger systems using pumps and controls some maintenance would be required for the electrical components. In case quality of water hard, scale deposition in the collectors may result over the years. This may require descaling with chemicals for which it is best to contact the suppliers. (In case of a forced flow system the pump and controls provided will require maintenance).

(6) Will the water be heated during monsoon?
On completely cloudy or rainy days there will not be any collection of heat and the water will remain cold. However on sunny day of the monsoon months, the "ATASH" Solar Water Heating System will give you hot water.

(7) What will i do then?
The "ATASH" Solar Water Heating System is designed to give you an electrical back-up with the "ATASH" Solar Water Heating System. In Mumbai there are about 25-30 non-sunny days.

(8) What is the use then of solar water heater?
We have estimated that on an average 300 days in a year are sunny and our "ATASH" Solar Water Heating Systems will work well on those days.

(9) What is the life of an “ATASH” Solar Water Heating System?
Some of our oldest systems are now 15 years old and are working trouble free. Over the years we have refined our technology and process.

(10) How much electricity and money can be saved?
Using a 125 LPD system saves about 4.87 units of electricity every day. That's about 1461units every year (Usage considered for 300 days a year).
If yours is a commercial use, then you save 1461 units @ Rs 7/- units i.e., Rs 10,227 every year.
If you are paying at the rate of Rs.4/- per unit, you save Rs. 5844 every year.
Also, don't forget the 100% depreciation benefit that you get for using a Solar Water Heater.

(11) What are the site requirements for installation of a solar water heating system?
The basic requirement for effective functioning of a solar system is availability of unobstructed sunlight for the whole day. There should be no obstruction to sunlight in the south, west and east directions. As a thumb rule, the requirement of shadow free area is around 3sq.m for each 1x2 m collector used. As far as possible, the area should be flat, away from rainwater drains and as far as possible, close to the bathrooms where hot water is to be supplied.

(12) How long will the water heated by solar energy remain hot in the tank? OR, will one get hot water in early morning when sun is not there?
Hot water produced by the solar system during the day is stored in an insulated storage tank. The insulation of the tank is such that water can remain hot without significant drop in temperature for around 24hrs. Thus water heated during the previous days would remain hot for use the next morning.

(13) Is any electricity required for operation of the solar heater?
No electricity is required for circulation of water. However, in case a back up heater is provided to take care of hot water requirement during cloudy days, electricity will be required.

(14) Are there any financial incentives from the government on these systems?
The Central Government through its Ministry of Non-Conventional Energy Sources provides soft loans for installation of domestic solar water heating systems. These loans are being provided through 7 nationalized banks and the interest rate on the loans ranges from 5% - 12.33%.

ESTIMATES OF REQUIREMENTS OF HOT WATER - SOME USEFUL THUMB RULES