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  • Sahil Mehta

Photovoltaic (PV) Solar Energy - Renewable Source of Energy for Water Pumping Systems

An increase in energy consumption is one of the critical issues faced globally majorly due to energy wastage. The term “energy wastage” is directly linked with an inefficient use of energy in our day-to-day life and is one of the topmost reasons for the energy crisis. The energy efficiency is only 42% in the US, which means 58% of the energy is either wasted or inefficiently used. To deal with this issue, Renewable energy-based sources like solar, wind, biomass, etc. which are easily available and are abundant in nature are the best alternate solution. In the year 2020, 12.6% of the energy consumed in the US was from renewable sources. Thus, these resources are very well employed for various energy-consuming areas/tasks like water pumping systems, etc. For a long period of time, “water pumping” has played a significant role in various applications like irrigation, drinking, cooking, etc. At a higher level, the other water pumping application is linked with sewage and drainage of wells, pools, etc.


Notably, like all other areas where renewable energy-based solutions are being deployed for energy conservation, the water pumping system is one similar area. Individually or in a group of pumps deployed for some application consumes a lot of energy. But, with the high potential of renewable energy sources, especially solar, this will be replaced in the future considering energy conservation and maximum energy extraction from renewables. The other core area of energy conservation on the same page is water pumping systems installed in rural and remote locations. At present, the transmission, as well as maintenance cost of the electrical lines along with the amount of energy consumed in rural areas for irrigation and like applications, are at the top-most priority. This will all be replaced with the solar photovoltaic-based renewable energy source, such that the quantity and quality of the electrical supply remain the same. With this change, the objective of energy conservation, maximum renewable extraction, and continuous/reliable energy supply for the water pumping system can be achieved.


Photovoltaic Water Pumping System

Conversion of solar radiation into electricity using the photovoltaic system to generate power for the water pumping system. The power produced by the PV system is supplied to the DC motor/AC motor to pump water out from the ground.


AC Pumping System


DC Pumping System

Flowchart - PV Pumping System

Step 1 – Receiving Solar Radiation: Initially, the solar PV panels are placed at the location site where there is maximum availability of sun for maximum hours of the day. Further, these PV panels receive the solar radiation/solar irradiance coming from the sun and convert the solar energy into its useable form.


Step 2 – System Controller: This multitasking device is used for a number of tasks, including maintaining the PV panels as per MPPT (maximum power point tracking), setting up the system voltage, pump on/off control, switching from PV to battery storage action, etc.


Step 3 – DC-DC Converter: This device is responsible for boosting the input voltage according to the system requirements. In the case of low PV panel output, the converter boosts the actual voltage such as to acquire the required voltage. Also, it is responsible for managing the battery storage charging and discharging operation according to the decision/action taken by the system controller.


Step 4 – Battery Integration: A battery module is integrated into the system to provide ancillary support as well as consume the excess power that is generated from PV during the off-working hours of the solar water pump. This battery storage device can further be used for any other application as required.


Step 5 – DC-AC Converter: This module is connected to the system only when the nature of the pump is AC, i.e., a single-phase AC supply is required to turn on the water pump. The main purpose of this module is to convert the incoming DC voltage to smooth AC voltage that can be fed to the pump directly. It, in other words, works as an inverter.

Step 6 – Water Pump: The key module of the system is the water pump. This component is responsible for pumping the water out of the well/tank for something useful. The pump can be located inside the well or on the ground with its inlet inside the water body/content/area.


Step 7 – Water Tank/Storage/Application: This segment of the system is responsible for storing the water pumped out to the well for something useful. In another case, the water pumped out of the well can directly be supplied to some applications, including, irrigation purposes, watering animals, etc.


Classification and types

The four types of solar water pumps include – submersible solar pumps, surface solar pumps, DC water pumps, and AC water pumps. The brief difference, advantages, disadvantages, and applications are discussed in this section.

Advantages

  • Location flexible – PV-based system can be installed almost at all locations around the globe as the resource is highly available.

  • Application flexible - Handling of water supply for irrigation purposes and feeding animals, pumping sewage waste, etc.

  • Work as a separate power supply source on summer days (ancillary support to power production).

  • Low-level need for protection devices

Disadvantages

  • High capital investment – Setting up a PV-based system with a Motor/Pump and a water storage tank needs high capital investment. However, this issue can be resolved with proper planning and a government budget.

  • Weather-dependent output – Solar is an intermittent energy resource and, thus, its output is solely dependent upon the weather conditions. But, with the battery integrated option, this issue can be resolved. However, with the upcoming technology, a combination of other resources like biomass can be quite helpful for such an issue.

  • Extra space requirement for water storage – Apart from the space requirement for solar panel setup, extra space is required for setting up the water storage tank. This way, some extra space is required.

  • Cleaning of PV panels – For efficient solar output, regular cleaning of panels is highly required. In the case of panels installed in a dusty region, the dust accumulates on the panels and causes the overall output to drop. This can also be linked with the concept of partial shading of PV panels.

Applications

  • Water for livestock – In rural areas, water availability for livestock is of great concern, especially where the number of livestock is more. Thus, solar based water pumping systems are the feasible solution. This allows the animals (livestock) to easily access water for drinking and other purposes. This also benefits the owners to not spend a number of hours taking the animals to a pond, etc., located far from the origin.

  • Farming and Irrigation – Water is essential for farming and irrigation purposes. Replacing the traditional system, which is not much reliable due to power cuts, a solar power-based water pumping system is the best solution. It allows the owners to operate the pumps at all times of the day without any concern about power cuts. However, storage devices are required in case of bad weather (non-sunny or cloudy days) where solar radiations are not available.

  • Drinking, Cooking and other purposes – For the regions that are located at remote locations from the source of water, it becomes difficult for the residents to travel to get an ample amount of water for daily chores. Thus, a solar power-based water pumping system is a boon such that it allows everyone around to use water for drinking, cooking as well as other household chores.

  • Water draining system/pumping sewage waste, etc. – Except for the residential level applications, one of the major water pumping applications is related to the drainage system. Although this application is not much explored with the solar power-based system, it can be well employed, as a matter of fact, where the issue persists on a regular basis, for example, in wastewater treatment plants.

Technical review and insights

Current trend

  • The use of more and more renewable-powered pumps in rural areas would reduce the weight on both the consumer as well as the government in terms of producing electricity and paying revenue for the same.

  • The use of solar power-based pumps needs maintenance time-to-time in terms of cleaning the solar panels, motor repair as well as maintaining the other electrical components.

  • Some policies relating to the use of solar-powered pumps can be revised where the limitations related to battery storage can be added.

  • Technological developments related to system efficiency are still a concern along with the integration of other resources and consumable electrical components, like solar power-based maintenance room, etc.

Technological developments

  • Ongoing research on solar PV panels and their efficiency.

  • Ongoing research on the integration of biomass with PV panels for a water pumping system, specifically for rural areas due to the high availability of biomass.

Patent analysis

The status of solar power has risen from 0.34GW in 2008 to 97.2GW at the present time. It is enough to light up 18 million US homes, in other words, solar power has powered up almost 3% of the total US population. This validates the potential of solar power in the US. Even an approximate drop of 70% in the overall price of solar panels and related products encourages people to opt for solar-based power generation options. In the upcoming time, the focus of solar panel manufacturers is on more rooftop-based projects along with rural projects including rural electrification, rural applications, etc.

China has been a leading country in the technological area related to solar photovoltaics and related applications like water pumping systems. To date, China has registered more than 14000 patents by 2021. Following China, the other country with the most significant number of patents in a similar field is the US, with over 1100 patents. Thus, it is evident that China leads the race to file the number of patents in solar photovoltaics related fields. Notably, also at the worldwide level, China offers multiple economical solutions to the issues related to solar technology. Such solutions include economical solar chargers/controllers, cheap solar panels, i.e., low cost per kW, etc.

As evident from the bove data set, China leads with a total of 14000+ patents. Similar to this, the top 3 patent assignees are also from China. Specifically, the list includes – SGCC (State Grid Corporation of China), Xian Polytechnic University, and Tianjing University. It is important to note that exhaustive research is still ongoing on the objective of low solar panel cost and high efficiency. Thus, it is expected that with the technological advancements in countries like China, the US, Japan, etc., the number of patents filed is expected to rise in the coming years.

From the patent filing data, the growth in the number of patents can be easily analyzed. From 739 patents filed in 2012 to more than 2000 patents in 2020, the solar photovoltaic-based water pumping system has seen a lot of growth. This not only includes the technological development in the solar panels but is also related to the electrical machine technology, improvement in the component material (chemical configuration of pipe, etc.), a method for finding the optimal location with higher water availability, etc. However, it is expected that by the years 2025 – 2030, the research in the field of solar panels will saturate such that the objective of the highest efficiency with low cost will be achieved.


Conclusion

The future of electrical power generation is tilted toward renewable energy resources. With the technological advancements, these resources have proven advantages in terms of power generation and electrification in rural and remote locations. In developed countries like the US, the scope of solar-based resources is in high demand, especially due to its decreasing installation cost, increasing applications, reduced electricity bills, and all-time available potential. In the same line of action, the water pumping system is another application where solar PV has proven its presence all around the globe. Specifically, the water pumping system includes different sub-applications like sewage and drainage of wells, irrigation, drinking, etc. Even with the integration of batteries, low-level operations, like irrigation, drinking, etc., are easily done while conserving the fossil-fuel-based generated power. This scope of source integration will increase over time, i.e., solar and biomass integrated projects for rural projects.


Discussing the technological developments, the number of patents filed is around 20K where China leads the list, followed by the US at the second top position. In addition to this, the increasing trend in the number of patents filed each year has also been observed. Thus, the scope of research in the solar-based water pumping system for a number of applications is still a hot topic. Henceforth, by the end of 2030, renewable energy-based power generation especially, via solar, will be a key asset for electrifying not only the residential load but also serving a number of real-time day-to-day applications.


References

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