**4. Experimental set-up of hybrid solar still with FPC and PVC**

The hybrid solar still had different types of heat sources such as a flat plate collector, photovoltaic collector and evacuated tube collector. The output of the solar still with ETC was investigated by Panchal et al. [3]. In this experiment setup we used FPC and PVC as additional solar heat sources as shown in **Figure 4**.

 In this still, output was improved as two more solar heat sources added heat to the basin water. The readings of the still were recorded and pure water was collected in a measuring flask. This hybrid still also produced electricity at night, which was stored in battery to heat the water at night. The output of the PV battery was 30 W and this was converted into AC using an inverter. The AC powered heater was used to heat the saline water. A similar AC heater running with PVC was used by Riahi et al. [4].

A solar still with a PVC panel can be used as a roof-top system designed by Gujarat government. The PVC panel can play the role of electric energy generation and water heating for the purification of water. This hybrid still technique can play an important role in the smart city project of the Gujarat government.

*Proceedings of the 4th International Conference on Innovations in Automation...* 

**Figure 4.**  *Experimental set-up of hybrid solar still with PVC and FPC.* 

#### **5. Effect of energy storing materials on the output of solar still**

In this experiment, sand and concrete were used as energy storing materials. The solar energy was stored in these materials and released at night so the output could be improved. In this experiment, it was found that energy storing materials improved the output by up to 0.5 ml/day. Other energy storing materials found to be very effective in the literature are rubber, dye, jute clot, semi-conductors, high temperature super-conductor and nano materials.

Tabrizi et al. [5] conducted experiments in a still using sand as a heat reservoir at the bottom and found productivity was 75% higher than in a conventional still.

Sakthivel et al. and Panchal [6, 7] explained that black granite gravel as an energy storing material improved the efficiency by up to 20%.

Rubber and charcoal have also been used in basins. Akash et al. [8] tested different materials in the basin and found excellent outputs. Naim et al. [9] stated that a still basin lined with coal enhanced the absorption capacity of the basin. It gave better results.

Patel et al. [10] tried to enhance the output of a solar still by using different semi-conducting oxides (Photo-catalysts) like CuO, PbO2 and MnO2. Elango et al. [11] conducted experiments with nano-fluids of aluminum oxide (Al2O3), zinc oxide (ZnO) and tin oxide (SnO2) and got better outputs. It is possible to use a high temperature superconductor as an energy storing material. The effect of high temperature super conductor (HTSC ) as an energy storing material will be tested in future work.

This research tested the effect of sand and concrete on still output. It shows an improvement. It is possible to test other energy storing materials as stated in above review.

#### **6. Result and discussion**

 The experiment was performed on 14–19 April 2017 and the following results were obtained for the conventional still. The average output of the test was 2 liters per day as shown in **Table 1**.

In the same way, the results were recorded for the other configurations of stills. The average outputs for the different configuration of solar still were recorded as shown in **Table 2**.

*Experimental Study of a Conventional and Hybrid Solar Still DOI: http://dx.doi.org/10.5772/intechopen.81083* 


#### **Table 1.**

*Yield of conventional solar still.* 


#### **Table 2.**

*Average output of different configurations of still.* 

 The active still and HSS gave better performance as shown in the above table. Energy storing material also affected the performance of the stills. The solar still with PVC can be used as a desalination device in the house whereas the PVC panels can be placed on the roof top of a house and electric energy generated by the PVC can be stored in a battery which can be used for heating the saline water in the still. This type of hybrid device can be developed to work with roof top system.

This hybrid system can be standardized and synchronized with the roof top system for the smart city project.

#### **7. Conclusion**

It has been found that the hybrid still gave the best results compared to other simple configurations of still. This research also suggests the use of other desalination techniques such as HDH and flash evaporation techniques with the solar still.

*Proceedings of the 4th International Conference on Innovations in Automation...* 

 The conventional still is the simplest method of desalination and is useful for small family needs. But the HDH and flash techniques of desalination will be designed, fabricated and tested for the arid region of Gujarat for the output of 40–70 liters/day. It is also found in review of different techniques of desalination that HDH, flash evaporation and solar still together can be tested for better output in future work. The nano materials discussed above as energy storage materials will also be tested in future work with the solar still and HDH desalination device.
