Solar pumps are bulky because of the panel size and as per problem statement trans-portability is required to prevent thefts. The innovative idea uses this limitation to an advantage. A cycle is modified with additional frame such that solar panel can be fixed on this frame with adjustable ball joints very similar to the ones used in beach umbrellas. With this joint the angle of solar panels can be changed in both directions to face the Sun. The innovation is unique in many ways as below.
1. Water pumping Solar mode: The cycle can be parked near the well. Suction pipe with foot-valve is put in the well. Delivery pipe is set where it is required. The solar panels can be adjusted with adjustable joints in a manner that the panel faces the Sun. Clutch for the pump is active. The power generated by solar panel is used to drive a motor through an electronic controller and the pump will operate through this DC motor and deliver water. Expected power to the motor is 100 watts with good Sun. Other clutch on chain wheel side remains disconnected.
2. Water pumping in hybrid mode: When solar radiation is not strong enough (in morning, evening and cloudy or foggy time) the other clutch of the chain wheel is also kept active. Cycle is put on stand and solar panel adjusted to the Sun. The farmer will sit on the seat of the cycle and peddle. Because of human power the rear wheel will rotate which in turn will rotate the chain wheel on the motor shaft. Hence now the pump gets power from the solar PV panel i.e. electrical input and also the human power i.e. mechanical power. For e.g. Solar panel may generate 40 Watt and person will add muscle power of around 60 watt, then the pump will get 100 watt of power. Both clutches are active in this case. Rear wheel of cycle will also work as a flywheel in this case.
3. Water pumping only in human power mode: At night hours when there is no Sun and if watering is to be done then both clutches will be active and farmer will pump the water by peddling alone. This will provide around 60 to 70 watt of shaft power through chain wheel to the motor shaft, other end of which is connected to the pump. Water delivered in this case will be say 30% less.
4. The farmer can use the same cycle to commute between his house and farm. Just wind up the suction and delivery pipe on the frame and drive cycle to home. Another innovation is added by the innovator here. While riding the cycle the farmer will set the solar panel angle in such a way that the panel gets maximum Sun and drives D.C. motor. The chain wheel side clutch is active and pump side clutch is inactive. Now the D.C. motor drives the rear wheel of cycle through the chain wheels. So the cycle will become solar cycle and will be driven by the solar panels. This will save peddling efforts for the farmer. In most of the cases panels can be so adjusted that the cyclist will get a shed of the solar panels and that will also add to the comfort of the cyclist. Suitable electronic controls will be added to adjust the speed of the cycle. A sketch showing the innovation is added.
For 1 acre of land water requirement as per ‘Jain Irrigation gravity drip system’ is 4000 liters. Presuming this water is to be pumped in 2 hours, the flow rate is 2000 liters per hour or 2 cum per hour. With 5 m head the power required is calculated as
Ph = (2 m3/h) (1000 kg/m3) (9.81 m/s2) (10 m) / (3.6 103)
= 27.25 Watts
Considering the pump efficiency at 60%, motor efficiency at 70% input power required will be
= 27.25 Watts/(0.60*0.70) = 65 watt.
Misc. losses say 25 watts. So net input power will be say 90 watt.
We choose a D.C. motor of 125 watts and also solar panels of capacity 125 watt peak capacity. In normal run the motor is expected to get 90 to 100 watts of power from solar panels which will serve the purpose.
When the system is only driven by human power and no Sun then the input power will be around 70 watts. In this case around 30% less water delivery is expected. Pumping hours may increase from 2 hours to 3 hours.