Solar Power

The earth receives 174 petawatt (PW) of incoming solar radiation at the upper atmosphere of which about 30 % is reflected back to space while rest is absorbed by clouds ,oceans and the atmosphere .The sun light absorbed by the oceans and the masses keeps the surface at an average temperature of 14˚C.

Solar is the light and radiant heat from the Sun that influences Earth’s climate and weather and sustain life. Solar power is sometimes used as a synonym for solar energy or more specifically to refer to electricity generated from the solar radiation. The human being used energy since he came on this planet for his well being million years ago .This tended to increase regularly, causing depletion of energy sources from the planet specially biomass and petroleum. It has a major challenge to human to explore alternative sources of energy. Solar has been found one of the most potential, yet untapped source of energy. This energy has to be trapped through passive mechanism as active solar use is costly. There are couple of issues that need to be addressed of solar energy popularisation.

Rural India depends on various sources of energy but major source has become biomass. Depleting biomass resource has thwarted community to state of recent energy crises. In mountains, biomass energy is used mainly for cooking, heating and drying. This entire energy dependence can be diverted to untapped Solar. A low cost, feasible and locally repairable solar system can be alternative energy for community. Such an initiative necessitates some local inputs both in front of R&D, demonstration and training.

There is abundant scope of trapping this untrapped source of energy for uplift of poor villagers as well as to create the eco-friendly environment. Some R&D task is needed for standardize of solar energy devices for mountains region .In context to mountain, under mentioned energy measures are important to address to reduce dependence on conventional sources specially biomass.

Cooking :
Biomass is the major source of fuel in mountains. About 90% of population depends on biomass fuel for cooking. Since it is women job, it takes 2-8 hrs. for collection of fuel .Huge amount of biomass is used in cooking here. Women while involved to other family chores allow biomass stoves constantly on fire for cooking pulses, which normally takes pretty longer hrs. causing use of lots of fuel wood . Besides, there is different timing of meal within the family .Women take meal in afternoon while other family members eat before noon. Such practice also tends to consume substantial fuel.

Water heating
Water heating especially in winters consumes lot of wood . It is simple practice that villagers fire stoves in the morning which keeps on heating water for the whole day for periodical use. This engulfs considerable wood, which can otherwise be diverted to some other source of energy.

Solar Drying
Drying is an excellent method to preserve food. There is a common practice in villages to dry vegetables and fruits on roof tops for off seasonal use. This method is normally unhygienic .Actually, solar food drying is one of the oldest technique related to food preservation, but every year millions of rupees worth of gross national product are lost through spoilage. There can be a solar drier service in villages that can not only help villagers for off seasonal consumption but also a new market avenues can be opened. Drying preserves food by removing enough moisture from food to prevent decay and spoilage . Water content of properly dried food varies from 5 to 25 % depending on the food. Successful drying depends on :

Enough heat to draw out moisture , without cooking the food.
Dry air to absorb the released moisture and
Adequate air circulation to carry out the moisture.

Solar drying food removes moisture as quickly as possible at a temperature that does not seriously effect the flavor, texture and colour of the food. If the temperature is too low in the beginning, micro-organisms may grow before the food is adequately dried. If the temperature is too high and the humidity too low ,the food may harden on the surface, making it difficult to dry. Dried foods are tasty ,nutritious , lightweight ,easy to prepare and easy to store.These foods are high in carbohydrates ,fibre and low in fat.

The above background necessitate appropriate solar device development with the following needs:

Wood saving:
The devices developed should be such that it should save forest biomass ,thus reducing the dependency on the forests .It is roughly estimated that by application of solar appliances in an average 30% to 40% wood can be saved by one family annually. The table below gives an idea of biomass use pattern in mountain villages:

S.No.	Activity	Average biomass used per family
		In Summer	In Winter
1	Cooking	8-10 kg	10-13 Kg
2	Water Heating	9-10 Kg	10-15 Kg
3	Drying

Thus 20-50 % biomass can be saved by adopting solar energy devices .These can be done through following inputs : Solar cooker/stoves Water heaters Solar driers

Design:
The design of the devices developed should be as simple as possible, easily locally fabricated and repairable by the community. Considering all the above mentioned factors ,the devices has been locally developed with locally available inputs.

Cost and Efficiency
Along with the feasible design ,the cost of the device developed should be such that community can afford it without much burden. It should also be very efficient economically in respect to its energy output .

Foreseeing all these aspects the following prototype devices are developed and are under continues study and trials:

Solar Cooker:
The solar cooker use sunlight for cooking, drying and pasteurization .They can be grouped into three broad categories :box cookers, panel cookers, and reflector cookers.

The simplest solar cooker-box cooker was first built by Horace de Saussure in 1767. It consists of an insulated container with a transparent lid .It can be used effectively with partially overcast skies and will typically reach temperatures of 90-150 dg C .Panel cookers use a reflective panel to direct sunlight onto an insulated container and reach temperatures comparable to box cookers. Reflector cookers use various concentrating geometrics to focus light on a cooking container. These cookers reach temperatures of 315 dgC and above but needs direct light to function properly and must be responsible to track the Sun.

There are varieties of solar cookers in market. But they do not meet local minimum criteria. Therefore a new solar cooker with above need has been designed that can match the minimum local need. These will be of two types, one for cooking and another for keeping the food warm. This is practiced in villages that women have to warm the early cooked food after fetching fuel and fodder.

On the basis of the above a HESCO solar cooker has been built with the following specification.

HESCO "Solar Cooker" has been developed using all locally available material as far as possible. The glasswool which is generally used as insulation material is replaced by the locally unattended pine needles . It is designed in such a way that it can be carried very easily from one place to the other without any breakage .Secondly Aluminium sheet is introduced as a reflecting media instead of mirror, thus making it more feasible for transportation. This cooker can cook food for a small family of 6-7 members . Its size can be as per the family need. As per the trial conducted during the last one year, the under mentioned table shows the variable results as per the season:

S.No.	Item	Quantity	Time Incurred (In Hrs)
			Summer	Winter
1	Rice	500	1/2	1.5
2	Pulses	500	1.5	3.0
3	Patato	1000	3.0	6.0
4	Beans	300	1.5	4.0
5	Cauli flower	1000	1.5	3.0

Result varies as per dependence on sunlight.

The size of the cooker is as follows:
Length----50cm.
Width-----50cm.
Height (internal)
Front –15 cm.
Back—20 cm
Clear Glass 40x40cm
Reflecting aluminium sheet—50x50cm
Thickness of cell---5 cm.
Filler material---Chir pine needles*
*material such as saw dust, rice husk, etc. can be used.

Water heater:
Women had been heating water particularly in winters for daily need. They use wood for the same and the wood is constantly kept burning for the above purpose. A rural solar water heater can help women to divert wood use to solar. Interestingly, this would also serve as solar distilled water too.

The solar distillation can be used to make saline or brackish water potable. Therefore solar water heater are essential in villages from the above point of view.Hesco water heater has the following specification.

HESCO introduced a water heater which is not only very compact but also very feasible to serve the individual families for their warm and potable water demand. It is also designed that it is very easy to transport from one location to the other as and when required.Its size can be varied as per the family size.

The heater presently designed and fabricated is of the size as mentioned:
Absorbing media or the absorber---1x2m
Over head tank----200ltr.
Storage tank -------300ltrs.

Solar Drier
Solar drier is practiced in villages particularly off time use of vegetables and fruits etc. A family size drier will be a great help to women. There is a commercial angle of the drier too. The dried fruits and vegetables have direct marketing future as resource utilization for income generation .Hesco drier has mainly been built to ensure that no fruits and vegetables can go waste. The Hesco drier has following features as under:

it is very easy to built and any local fabricator/sheet metal worker can built it without any problem.
the material used is locally available and all the material needed are easily available even in the remote market.
is portable.
easy to handle and durable.
very efficient for drying all types of fruits and vegetables.



As per the trials taken during last one year the followings are the observations:

S.No.	Item	Quantity	Time Incurred (In Hrs)
			Summer	Winter
1	Gooseberry	5.0	3.0	6.5
2	Potato Chips	5.0	10.0	18.0 to 20.0
3	Red Chilly	3.0	6.0	15.0 to 17.0
4	Ginger	5.0	12.0	18.0 to 20.0
5	Cauli flower	5.0	4.0 to 4.5	8.0 to 9.0

Result varies as per dependence on sunlight.

The HESCO drier has following specification:
Drying unit
Length ---60 cm.
Width------60 cm.
Height ----1.5m
No. of trays—4
Depth of each tray—10cm.

Absorbing unit
Length ---1.2 m
Width ---50cm
Depth of air chamber—20 cm
Height above ground
Back ----50cm
Front----20cm.
Glass thickness----4 mm(clear glass).