Solar Steam Cooking System

A parabolic type concentrating solar steam cooking system was commissioned at Shri Saibaba Sansthan, Shirdi on 24th May, 2002. This system received financial assistance of 50 % of the total project cost from the Ministry of Non-Conventional Energy Sources, GoI. This is the first of its kind in Maharashtra. It cooks food for about 3000 devotees.

The 40 nos. of solar parabolic concentrators raise the water temperature to 550C to 650C and convert it into steam for cooking purposes. This system is integrated with the existing boiler to ensure continued cooking even at night and during rain or cloudy weather. The solar cooking system installed at Shirdi follows the thermosiphon principle and so does not need electrical power or pump.

Shirdi is a religious pilgrimage centre and thousands of devotees visit the Shirdi Sai Baba temple daily. Shri Sai Baba Sansthan at Shirdi is an autonomous body (Trust) to provide facilities to the devotees.

Shirdi is located near Nasik. Other nearby cities include Mumbai, Pune, Ahmednagar and Aurangabad.

The latitude of Shirdi : 19.5 degrees north
The longitude of Shirdi : 74.5 degrees East.

The Sansthan has a prasadalaya where it offers food (prasad) to the devotees at subsidized rates. Thousands of devotees partake food at a nominal rate of Rs.4/- per meal for grown ups and Rs.2/- per meal for children.

The Sansthan is always on the lookout for innovative ways to reduce its overhead costs. They have installed hot- water- systems at its dharmashalas / dormitories, providing staying facilities for devotees.

In the Sulabh Sauchalaya complex located in its premises, to night-soil-biogas plant is installed to generate gas from human excreta, which is used to operate generators to produce electricity for the complex.

The Sansthan has also installed solar streetlights in its pumping complex. Thus it was found to be the ideal place to introduce the new solar steam cooking technology for its proper take-off in Maharashtra state.

Before the installation of the solar cooking system, the steam for cooking at Sansthan was being generated by LPG gas firing in the boiler.

The main goal of the system was to reduce LPG gas consumption by 50 %.
Another important goal beside financial benefits due to saving LPG gas was to use as much natural energy as possible to promote environment protection, its conservation and rejuvenation by using renewable and clean energy.
To promote and popularize use of solar energy. MNES and MEDA have supported this project towards realizing this objective.

The solar steam cooking system installed at Shirdi has 40 parabolic concentrators / dishes (called Scheffler dishes after its inventor) placed on the terrace of Sai Prasad Building No.2.

They reflect and concentrate the solar rays on the 40 receivers placed in focus. Water coming from the steam headers placed above the header centres is received from bottom of the receiver, gets heated up to due to heat generated (about 5500C) due to concentration of solar rays on the receivers and get pushed up via top pipe of receiver into the header. The principle of anything that gets heated is pushed up is called thermo-siphon principle. The advantage of thermosiphon principle is no pumping (thus no electricity) is needed to create circulation since the heated water is pushed into the header and water from the same headers come into the receivers for heating. The cycle continues till it reaches 1000C and gets converted into steam.

The header is only filled and thus steam generated gets accumulated in the upper half of the steam header. The temperature and pressure of steam generated keeps on increasing and heat is stored till the steam is drawn for cooking into the kitchen.

All the 40 dishes rotate continuously along with the movement of the sun, always concentrating the solar rays on the receivers. This movement of concentrators is called tracking, which is continuous and is controlled by the fully automatic timer mechanism.

Only once during the day i.e. in the early morning the dishes have to be turned manually onto the morning position, subsequently the automatic tracking takes over.