Milma Dairy, Kozhikode, Kerala

General Information on the company using solar thermal energy

Description of the company

Kerala Co-operative Milk Marketing Federation (KCMMF), popularly called ‘MILMA’ was established in April, 1980. The head office was established at Trivandrum for the successful implementation of ‘Operation Flood’ programme in Kerala.

It is a three-tiered organization. At the grassroots level MILMA has 3059 Anand model primary milk co-operative societies as on 31.03.2012 with 8.6 lakh local milk producing farmers as members. These primary societies are grouped under three Regional Co-operative Milk Producers’ Unions viz TRCMPU for Thiruvananthapuram region, ERCMPU for Ernakulum region and MRCMPU for Malabar region.

Type of Industry

Enriched milk and various milk-based products as well as mango drink products for supply throughout the state of Kerala.

Location of the company and the solar plant

The solar system is installed at the location of: M/s Milma Dairy,
Kerala 673 571.
Key Contact: Mr. Prem Anand, Plant Incharge
Ph : + 91 9446072396

Heat demanding processes

The heat demand required for the Dairy plant is about 5-8 hrs per day. The generated steam at temperature of 110°C used for various purposes. The generated steam is used for washing, cleaning of dairy flours and utensils.

Conventional heat supply

Two fire tube boilers are installed in the plant with 1.5 TPH (Furnace Oil based Boiler) and 2 TPH (Biomass based Boiler). The furnace oil based 1.5 TPH boiler is usually on stand-by and 2 TPH Biomass based boiler operates with the solar water heating system.

Conventional fuel used

Briquettes are produced from the biomass. In case briquettes are not available then Furnace oil based boiler is used.

Motivation to use solar thermal energy

Production cost increases due to annual inflation in furnace oil prices. This was the triggering point for MILMA dairy to look for alternatives. This led to adoption of SWHS.

Description of the solar thermal system

Type of solar plant

FPC based industrial Solar Water Heating System plant with a storage tank of 10000 liters capacity. The system is used for preheating the feed water which is sent to the boiler.

Year of installation

The solar system was commissioned in February 2003.

Solar collector field

The solar thermal system has 120 FPC collectors with a total 276 sq. meters aperture area.

Water storage

The collector arrays are connected to a non-pressurized water storage tank with a storage volume of 10,000 litre.

Hydraulic scheme & operation of the system

Plant is working in two shifts of 8 hours each. From the solar system the hot water is being supplied from 10am to 5pm to the boiler. The system is operated manually. RO water in the collector loop is circulating as a heat exchanger fluid and transferring heat through the plate heat exchanger to the water circulating from the solar storage tank. The system is a closed loop system. The solar water tank is filled with 10,000 litre tank is filled with RO water in the morning time. The water from the storage tank is sent to boiler for generating steam at 110°C and sent to the process requirement.

Supplier/ manufacturer of the solar system

The solar system was designed, delivered and commissioned by:

M/s Tata Power Solar Systems Ltd.,
78 Electronic city Phase 1
Hosur Road
Bangalore 560 100
Key Contact: Mr.Naresh
Ph : +91-80 6777 2000, 3000

Data recorded

The plant personnel maintains the records for boiler feed water input and briquettes consumption per hour. Logbook records are available since the SWH plant is in operation however plant in charge unable to provide the records.

Energy balance and economy

Heat demand

It is assumed, that the factory requires 10,000 liter per day of 110°C hot water and the cold water temperature is equal to the annual average ambient temperature of 25°C.

The daily energy demand for hot water heating can be calculated with:

Qdaily = 10 m3/day * (110°C – 25°C) * 1.16 kWh/(m3*K) = 986 kWh/day

The annual energy demand for hot water heating is:

Qannually = 365 days * 986 kWh/day = 360 MWh/year

(The temperature difference in °C is measured in K (=Kelvin))

Solar radiation-on site

The site receives an average annual solar irradiation of 5.53 kWh/(m2*day), this means 2018 kWh/(m2*year) on horizontal surface. On collectors with an inclination of 30° the irradiation is about 0.99 * 2018 kWh/(m2*year) = 1998 kWh/(m2*year).

Location: Longitude: 75.78 E & Latitude: 11.25 N

Source: NASA Surface meteorology and Meteonorm

Useful solar energy delivery

The solar radiation on the collector surface is 276 m2 * 1998 kWh/(m2*year) = 550 MWh/year. Assuming a system efficiency of about 20%, the useful solar energy is about 550 MWh/year * 0.2 = 110 MWh/year, which corresponds to 302 kWh/day. The useful solar energy delivered by the SWHS per m2 of collector is: 1.09 kWh/m2.

Fuel saved by solar energy

Due to implementation of the SWHS project, resulting in displacing about 82 kg/day or 30 tons/annum which is being used for firing in the boiler.

Assuming 70% boiler efficiency and Gross calorific value of fire wood as 5.23kWh/kg.

Emissions saved

The CO2 emissions saved by the solar system are of about 63 ton CO2 per annum.

(Assuming emission of 2.11kg CO2/kg of fire wood)


Investment costs

The project is commissioned with an overall investment of Rs.9.2 lakhs

This corresponds to INR 3333 per m2 collector area.


No subsidy received neither from Central nor from State government.

Economics of the solar system

Assuming price of fire wood as Rs 6/kg. The SWHS is saving around Rs 1.8 Lakh/annum. The simple payback period is around 5 years without capital subsidy.


Operation experience

Overall performance of the system is good. Due to lack of maintenance from the manufacturer certain problems occur like leakage of water due to rust in the pipes.

Statement of the owner

Owner is unsatisfied about the operation of solar system because of poor maintenance support.

Statement of the supplier/manufacturer

Manufacturer expects subsidy from the Government of India to increase dissemination amongst industry consumers.