Large Solar Basket

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Large Solar Basket, designed by V K DESAI of From TinyTech India
Large Solar Basket, designed by V K DESAI of From TinyTech India

From TinyTech India -

I have designed large solar baskets from 4 mt dia to 12 mt dia. It is one type of solar concentrator in parabolic shape with short focal length. So focal point is inside the basket near the vertex. It has a benefit that heat receiver is protected from the wind and convection losses will be minimum. I have designed light weight solar baskets of 5 different sizes.

(1) 4 mt dia,12.5 sq mt aperture area and 21.3 sq mt reflector area.

(2) 6 mt dia, 28 sq mt aperture area and 48 sq mt reflector area.

(3) 8 mt dia, 50 sq mt aperture area and 85 sq mt reflector area.

(4) 10 mt dia, 78sq mt aperture area and 78.6 sq mt reflector area.

(5) 12 mt dia , 113 sq mt aperture area and 191 sq mt reflector area.

All these solar baskets will be used in millions of number for mass cooking, for industrial heat everywhere and for power generation in farms and villages.

Design is so much simple that any clever technician can copy it and start manufacturing of solar baskets. As per my estimate there is a huge scope of 30 million solar baskets in India for solar water pumping and for running small family size industries like cotton ginning, cotton spinning, rice milling, oil milling and various rural and urban industries with self generated solar power. So people will become totally autonomous and free from electricity companies. Entire world scope out of India for such solar baskets is more than 100 million baskets. Entire solar basket will be moving with the sun on horizontal axis and also on vertical axis around the focal point. Heat receiver is fitted on the focal point and not connected with the basket at all. So it is fixed with ground and not with the basket. So the entire device is so ingenuous that still focus remains on the heat receiver for the whole day.

I have developed prototypes. 4 mt dia, 6 mt dia basket , 8 mt dia baskets and 12 mt dia basket are already erected on the foundations. Focal boiler of 4 concentric coils of 1" dia pipe has been fitted. I have used square pipes of 50 mm x 50mm x 1.5 mm metal thickness for construction of paraboloid up to 8 mt dia. For 12 mt dia I am using 50 mm x 50 mm x 3 mm square pipes. I give below basic design and construction process.

Basic formula for paraboloid is Y = X2/4F where X is horizontal coordinate and Y is vertical coordinate. We have to assume F i.e. focal length. For 8 mt dia I have assumed 1000mm as focal length. Now assume X= 100 mm, 200 mm, 300 mm, 400 mm up to 4000 mm( 4000 mm becomes 8 mt dia). Now using the above formula , calculate Y coordinate for all X coordinates. So you will get table of 40 values of X and 40 values of Y. Then you can draw a curve of actual size on factory floor. This curve should be preserved with dimensions in fast color so that it remains permanently and often it is used for measuring and copying. Now every X coordinate is a radius of a circle. So you have dimensions of 40 circles out of which you can select 10 circles roughly at equal distance. Then fabricate the circles from square pipes. It will be preferable to make small pipe bending press of your specific requirement or sub contract of making circles . When I had no pipe bending facility, I cut the pipes into small pieces and made 16 sided polygon for each circle. But better to have real circles. Then for vertical supports I bent 16 parabolic shape pipes. Just by copying the curve drawn on factory floor. Now I have developed pipe bending machine and 12 mt dia basket has been made on this machine.

And laterally I have also connected the circles by parabolic shape square pipes on outer sides by bolts and nut so that entire basket became folding. Focal point is passing through 4 mt dia circle on which hinged brackets should be welded to support entire basket on the bottom frame which can revolve around the vertical pipe fitted on the foundation. Now you will understand that entire weight of the basket goes on 4 mt dia circle. So all circles smaller than 4 mt dia carry no weight at all. So we make it light weight from iron stripes and we call it TOPO (cap) which means cap from apex to 4 mt dia small paraboloid. Cap is folding so that we can remove TOPO and introduce focal boiler or heat receiver.

I have welded and tied 8 mm round bars with stainless steel wire to support the reflector sheets which is anodized aluminum. The main feature of my solar baskets is simplicity for manufacturing. Generally in Western world solar concentrators are costing US$ 300 per sq mt of reflective surface. I have estimated that my solar baskets will be costing US$ 100 or less per sq mt.

There is problem of balancing the solar basket. In the morning and in the evening weight of the basket is on one side and so we had to utilize hydraulic jack for raising or lowering solar basket. Then supporting the solar basket in the morning and evening will be controllable by only one person. This work is so easy that even skilled rural welders and technicians can grasp and copy it very easily once they have seen it. And that is exactly what we require. Such solar baskets should be manufactured in hundreds of numbers in every village and in all the farms. Then quick solar revolution will come. Solar baskets will be used extensively. I am very much optimistic that once technology goes to grass root level, rural people will make solar baskets from wood, bamboos, ropes and other cheap materials. And then solar baskets will play very important role in making solar energy viable everywhere and it will compete very easily with giant thermal power plants.

I have to still make experiments how much steam it generates. Sun tracking on vertical axis and on horizontal axis is also manual at the moment. Because of monsoon I am unable to test until October 2014. I hope to use 12 mt dia basket as solar crematorium. If successful prima facie, I will make splendid electronic digital devices, showing burning body, weight burnt and to be burnt, total time for burning and how much time remaining etc on the projector screen. My solar baskets will really revolutionize many industries requiring heat and power both. Ice plants, cold storages, small dairies and all agro processing industries will run at small scale level in villages and farms and real wealth and prosperity will be generated in rural areas. So solar baskets will play most important role to transform world economy from oil based to soil based and to materialize Mahatma Gandhi's cherished dream of Gram Swaraj.

RAJKOT 360002
91 281 248 0166 (office)
91 281 246 7552 (fax)
91 92 27 60 65 70 (mobile)


For big kitchen serving thousands of people every day, solar steam system through many Scheffler reflectors integrated as a steam producing plant is the best available system. Scheffler system gives the facility of indoor cooking by steam produced automatically in an integrated system of Scheffler reflectors which is highly scientific device invented by benevolent scientist Mr. Wolfgang Scheffler. It is now commonly used at many temples of India serving solar cooked meals to 1000 to 20000 people per day. We have developed cheaper and simpler alternative of Scheffler reflectors which is far more user-friendly than Scheffler reflectors. We have developed 12 mt dia solar basket aperture area 113 sq mt and reflector area 191 sq mt which is almost equivalent to 10 Scheffler reflectors of 16 sq mt, If its aperture area is 70% of 16 sq mt. OR equivalent to 9 Schffler Reflector of 16 sq mt, if its aperture area is 80% of 16 sq mt.

Main benefits of our 12 mt dia Solar Basket are as under:

(1) It is not necessary to find out north south direction in our solar basket , it is essential to fix north-south line and fit the cooker on that line with foundations. This is highly scientific work.

(2 )Solar basket does not require to install on polar axis. So no latitude of the location is necessary to know. In Scheffler Reflector, it is essential to fix entire structure to revolve around polar axis and hence latitude of the location must be known. This can be done by highly trained technical person.

(3) Solar basket does not require any seasonal adjustment. In Scheffler Reflector, it is essential to make seasonal adjustment every week, which also requires training.

(4) In our solar basket, 100% aperture area is utilized all the time as against 70 to 80 % aperture area is used in Scheffler reflectors.

(5) The cost of 12 mt dia solar basket is about 9 lakhs while 9 Scheffler Reflectors will cost 18 lakhs. So our cost is only 50%.

(6) Space requirement will be only 20% of Scheffler reflectors.

(7) Disadvantage: Scheffler Reflectors have automatic tracking devise. Our solar baskets have manual tracking devise.

On the whole,solar baskets are highly user-friendly and any layman or illiterate person can cook without training. Scheffler reflector is highly scientific device which can be understood only by scientists and highly trained engineers. So, training is necessary to maintain Scheffler reflectors and to make seasonal adjustments.

Regards, V K DESAI

Tagore Road, RAJKOT - 360002, INDIA
91 92 27 60 65 70 ( MOBILE)
SKYPE-- vkdesai1
91 281 243 1086 (HOME)
91 281 246 7552 (FAX)