In many villages and oases far from cities, the public electricity network connection service may not be available in addition To the possible absence of running water sources such as rivers, lakes, etc. To meet the needs of those residents
The areas of water, whether used for irrigation, agriculture, drinking, and other uses, depending mainly
On groundwater wells, which are likely (or often) at varying depths, so the importance of using them appears Pumps to raise water. In these areas, the energy sources used to run the water-raising pumps are either diesel or using a solar pumps.
WHAT IS A PUMP ?
It is a mechanical unit that draws water from the well and pushes it up with a certain pressure, and it derives its power from a motor Electrician . The pump consists of a fixed body (the casing) that contains a vacuum attached to the suction tube and connected The vacuum is from the top of the pressure tube, and the fan draws water and pushes it out.
Figure (1) shows a European piston pump, which first appeared in the fifteenth century with the knowledge of:
1450 : Dicovered by Mariano di Jacopo (1382- 1453 )
In 1475 Francesco di Giorgio Martini ( 1439-1501) Improved the pump .
Figure 2 shows an old (1924) manual water pump at Alapah school, Georgia, in the
COMPONENTS OF SOLAR WATER PUMPING SYSTEMS
Usually, water is found in sewers and wells, where energy is needed to raise it to the level of use, and energy is required to pump it In pipes and transporting them to areas of use, man has used a variety of energy sources, which is energy Human, animal, water, wind, solar energy and fossil fuels) such as using diesel
Small generators (.) Water pumping systems have a long history, as they developed from the use of human effort, then The energy of draft animals and the natural energies they provide, such as wind energy, and when petroleum and electricity products appear, etc.
Its owner produces engines and then takes advantage of solar energy, which compensates for traditional energy sources.
Pumping systems used in remote communities
- Hand pumps link
- Animal driven pumps
- Hydraulic pumps
- Wind pump
- Diesel and gasoline pumps
- Gravity pumps -Difference teams
There are many types of fossil fuel pumping systems, including diesel engines. Figure (2) illustrates
Diesel engine water pump, raising water up to 35 meters, maximum water volume 1366 liters / minute, capacity 15 horse.
Figure (3) shows a reliable and powerful water pump equipped with a diesel generator. This generator has a manual pull start with a switch
Electric start. Anti-vibration and oil reduction and fuel gauge. A diesel generator is a combination
From a diesel engine with an electric generator to generate electrical power. Typically a compression ignition diesel engine is designed
To run it on diesel fuel.
Solar energy can be used in water pumping systems in one of two ways:
- By using solar cells as a source of electricity and thus using an electric motor driven pump.
- Using the central thermal energy in the parabola to produce thermal energy that powers the Stirling engine Which in turn turns on the pump.
In this section we will only cover pumping systems using solar cells
Photovoltaic solar water pumping system, which is similar to the traditional pumping system using electricity
But solar energy is used instead of fossil fuels (diesel) or general electricity.
In 1978 NASA’s Lewis Research Center first built the first PV system by installing a plant
A 3.5 kW photovoltaic capacity is on a reserve in the Indian village of Papago in southern Arizona – where
The system was used to provide pumping water and electricity to 15 homes until 1983, when the grid was connected The village was then assigned a PV system to pump water only to the village.
Table (1) shows a comparison between solar-powered pumping systems and traditional methods and Table (2) shows the advantages and disadvantages of solar-powered pumping systems
|Solar pumping||Pumping with traditional methods|
|1.It does not require any fuel or electricity to operate.|
2.Do does not bear the recurring costs of electricity or Fuel.
3.It is not affected by the occurrence of changes in the voltage of the source.
4.To be installed in remote areas where it is not available Electricity or difficult situation to get
5.Low maintenance( fewer parts
6.There is no possibility of contamination of the water/soil.
7Easy to implement
|1.Requires fuel or a source from the public grid.|
2.Exposure to or being affected by the problems of the public electricity network.
3.Affected by changes in the source of electricity.
4.It needs maintenance (because there are a number of parts Animated ).
5.Causes water/soil pollution from diesel use
Lubricants needed for operation
|1.Solar energy is available regularly|
2.You do not need an alternate power source which
reduces operating costs.
3.It works automatically after sunrise) or as per
Controller Driver (no need for me
Human follow-up, which reduces operating costs.
4.Ease of installation
5.You do not need cables to connect to the public
6.Clean and environmentally friendly energy that
does not lead to pollution Groundwater or air
( as in pumps that Diesel-powered )
7.Lack of infrastructure costs for water and electricity Public networks.
|1.The high initial cost of the system|
2.As a result of reduced energy output from cells
Solar than the winter, the flow rate decreases
Water from solar pumps by up To 30%.
3.DC pumps require technical expertise
Especially for maintenance
4.In the case of trees or tall buildings, or
Obstacles in the location of solar systems, and must be removed.
The solar water pumping system consists of:
- Photovoltaic array and accessories.
- Inverter to convert direct current (DC) to alternating current (AC) (in case the pump motor is of the AC type)
- The pump and motor assembly and its accessories that convert the electrical outlet of the photovoltaic array to Hydraulic power
- A set of batteries (optional if needed)
- Well, pipes.
- Power supply cables.
- A water tank and a water distribution system, which distributes water to the areas of required use.
Figure (4) shows the components of a solar water pumping system
There are two types of electrophoresis water pumping systems according to the type of electric current used:
- AC water pumping system, in this system the pump is fed from the outlet of the inverter
- DC water pumping system, in this system the pump is fed from an outlet
Matrix or through a storage battery pack and a charging regulator.
#1. Solar Electric Pumps
There are two main types of pumps
Figure (5) shows a representation of a solar water pumping station using a surface pump, due to the simplicity and ease of this type.
The pump can be transportable from one place to another, and the photovoltaic power station is also installed on wheels for easy transportation
Each pumping station is from one place to another,
and Figure (6) shows a solar pumping station using a set of a pump and a surface motor;
2.Submersible solar Pump
While Figure (7) shows a solar water pumping station using a submersible pump, and the pump is used Submersible either as a complete unit integrated with the motor, as shown in Figure (8), or the motor is installed on the surface of the pile, if The efficiency of this type is low due to the power losses from the drive shaft between the motor and the pump, and from
The disadvantage of high installation costs, as shown in Figure (9).
Figure (10) illustrates an electro-solar pumping station using a submersible pump and a DC motor,In this type, the station contains a control unit consisting of a current regulator and water level sensors
The purpose of this unit:
• Matching the electricity that reaches the pump with the electricity generated from the photovoltaic panels
• Protection of the pump against low/high voltage, The electricity exit system shuts off if the voltage is too low or too high for the pump operating voltage range.
#2 Solar Panels
It relies on producing electrical energy by converting solar radiation into direct electricity with a semiconductor.
1.Type of solar panels
The properties of a solar panel or solar cells vary according to their quality, and the most important of these characteristics is efficiency.
Solar panels are divided into three popular types:
- Mono-crystalline solar panel which is considered the best in terms of efficiency.
- A polycrystalline solar panel is less efficient but less expensive.
- A thin-film solar panel is flexible and easy to install, but its efficiency is lower compared to the other types.
2.Variables used to describe the properties of solar cells
- Maximum Power at STC (Pmax)
- Optimum Operating Voltage (Vmp)
- Optimum Operating Current) (Imp)
- Open Circuit Voltage ( Voc)
- Short Circuit Current (ISC)
For more details about theses, 5 parameters read: 5 paramerters of an i-v curve
- Module Efficiency
- Operating Module Temperature:It expresses the operating temperature at which a solar cell can operate.
- Maximum System Voltage
For more details about the last parameters this Article
#3 The Solar Pump DC/AC inverter
As the intensity of solar radiation varies during periods of the day, this leads to a change in the speed of the pump operating Powered by solar energy throughout the day. Hence the need for a means or equipment that has the ability to control the speed of AC pumps from the moment they operate at sunrise to the moment they are stopped at sunset, through their normal operation during the day.
An inverter is an equipment for converting direct current (DC) to AC power for the purpose of feeding the pump motor with AC voltage (AC).
As shown in Figure (13), the available capacities of inverters start from about 1 to 300 KW, and this covers flow rates Water reaches 450 cubic meters per hour.
If an AC motor pump is used then the system needs an inverter to convert the current Continuous (output from solar panels) to alternating current.
Functions of the inverter
- Control the starting of the motor by gradually raising the voltage and frequency value from zero until it reaches speed Programmed prime or reference speed during a time period known as acceleration time which is predetermined and programmed.
- It stops the motor by gradually reducing the voltage and frequency value from the value set at the moment of the shutdown request Until it reaches zero within a fraction of the time period known as slowdown time It is predefined and programmed.
Inverters for pumps with less than 2 HP usually have a single-phase current outlet, while inverters for pumps with more than 2 HP have an AC outlet Three phase.
Most modern types of inverters for solar pumps have inlets equipped for both diesel and electricity from the grid , in order to obtain a hybrid system that works as a backup source of energy in addition to solar energy.
The output of the inverter has a variable frequency current from 0.0 to 60 Hz according to the instantaneous solar radiation intensity.
The inverter is provided with a soft starter element, and its function is the soft straightening for motors
of Large and medium capacities in order to reduce the starting current which is high when the motor is directly started Through a contactor to gradually raise the load speed from zero to the maximum speed. This property allows using a small inverter rather than a large power inverter to withstand the large starting current that occurs at the start of an induction motor.
The electrical properties of the inverter
#1.PEAK POWER, TYPICAL POWER,AVERAGE POWER,Maximum continuous voltage
PEAK POWER: Also known as surge current, it is one of the most important characteristics of the inverter that is useful when choosing it. It expresses the maximum power that an inverter can handle in a specified time, usually ranging from a few seconds to Up to 15 minutes.
Note : Motors have a characteristic that they draw high wattage when they start. So when using an inverter to run An engine must choose an inverter that has a maximum power equal to or greater than the power drawn by the engine at the start of its run Likewise, the duration of the inverter’s maximum power period must be longer than the period of the engine’s maximum power when it is running.
TYPICAL POWER: It represents the average electrical capacity during the normal and continuous use of devices that consume AC electricity The typical power value of the inverter is chosen equal or greater with the power of the pump motor during continuous use (And not during the start of work)
AVERAGE POWER: The average power of the inverter compared to the time it was used. That is, this value has a relationship with the time the devices are operating Consumed. The greater the period of use, the greater the average electrical capacity required( This feature is not used when choosing the right inverter ).
Maximum continuous voltage:It expresses the maximum continuous effort that it can withstand. In the case of the solar power system connected to the public grid, the total open circuit voltage should not exceed the value of the maximum continuous voltage of the inverter.
In the case of a grid-independent system, then the total voltage of the batteries should not exceed this value.
#2.Controle of Charge annd discharge
Most inverters used with solar pumps are of 3-phase type and most have a voltage regulator; It also needs a simple electrical circuit with some protections to protect the motor and the pump against damage to it In the event of an overload, it may result from a clog in the pipes, the entry of some impurities into the pump, or the drying out of the water.
Figure (14) shows a representation of an inverter containing an internal voltage controller.
- Solar charge controller functions
It is an electronic device that regulates the incoming electrical voltage from the cells before passing it to the batteries and The battery is subject to the electrical load in order to preserve the used batteries and to ensure that they are charged and used Optimally. Figure (15) shows the functions of the solar charge controller.
- Regulate the charging of batteries
- Regulate the electrical voltage coming from the module before it reaches the batteries
- Display Charge Level
- Type of solar charge controllers
- 1.Pulse-width modulation ( PWM).
- 2.Maximum Power Point Tracking) MPPT
- 3.Built in Solar charge controllers
For more details about solar charge controllers and their functions read :3 types of solar charge controllers
Some inverters have General Packet Radio Service (GPRS) And a Global Positioning System (GPS) that users can use Monitor the solar pumping system completely online from anywhere through the remote monitoring system for the computer. Which can automatically calculate the current flow velocity, flow per day, current power, total output, and more Of the state variables for the solar pumping system. Figure (16) illustrates remote monitoring through the inverter.
An example of an inverter of a solar water pump
Figure (17) illustrates this type, and the following are its characteristics
The idea of the inverter working is summarized in:
1.Converting the energy from solar radiation (DC) into mechanical energy to drive the motor and pump the water at a specified rate of flow of altitude.
- Wireless monitoring system available for remote control.
- Available in capacities from 0.75kw to 250kw.
- Contains a pump control (optional).
- The ability to program to control the water level of the tank and protect against operating the pump in case the water dries up.
- Recording the total energy produced from the solar cells (KWH)
II.Intelligent pump control
• Automatic start/stop of the pump motor based on the intensity of sunlight.
• A time delay to restart the logical automation of drip irrigation systems.
• Control to reduce the pump operating torque
III.Maximum capacity point tracking control system
- This feature allows maximum power point tracking (MPPT) to obtain the best available power output from Solar cells While controlling the start and stop depending on The sun rays, which saves fuel and money during daylight hours.
- Optimum use of solar cell energy.
- Control and change of the inverter output according to the power demand and availability from sunlight.
IV.Water level sensor
1.For bore wells
It stops pumping water when the water level drops below the beginning of the level and starts pumping water when water is above the starting level. This protects the engine automatically.
It stops pumping water when the water level rises from the highest starting level and starts pumping water when The water level drops below the starting level.
- Producing capacity
- Engine speed (Hz)
- Motor current (Ampere)
- Solar cell voltage (VDC)
#4.Group of Batteries
Solar Batteries are used to store the reserve of solar energy produced from solar panels, which should be characterized as having a Deep cycle, and is described by the following variables:
- Voltage is measured in volts (24V or 12V).
- Current is measured in amperes
- Power is measured in watts
The Battery capacity is indicated by the value of Amps-Hours (Ah), for example, battery capacity
12V / 200Ah, in theory, this means that it can get a capacity equal to 12 * 200 watts, i.e. 2400 watts.
In practice, however, it can not be discharged by more than 50%, meaning it gives a storage capacity of only 1200 watts. Can be up Deep cycle batteries discharge to 80% of their capacity.
There are two common types of solar energy batteries
- FLA – Flooded Lead Acid: Lead plates are completely immersed in an electrically ionized liquid. Which must be changed every certain period. This type It is the oldest and most widely used one, with a capacity between 100 & AH 500 and a lifespan of up to 10 years
- VRLA – Valve Regulated Lead Acid:
This type is similar to the first type except that the fluid inside it is not changed. It is almost maintenance-free and has a quantity release neglected from hydrogen gas, which makes it easier to transport and install, and it is not considered dangerous to handle.
There are three main types:
- Wet: In this type, the battery performs approximately 500 deep discharges for about 50% of its charge it is an economical type.
- Absorbed Glass Mat)( AGM): It is an electrically ionizing liquid that has been absorbed into a sponge mat.
- GEL: It is lead immersed in a liquid that has been converted into something like jelly, meaning that it has become less and more fluid Tenacity This type is the best, more efficient, and has a longer service life. It can also do a cycle Deep discharge that may reach 60% of the charge contained in it.
Characteristics of some types of batteries used in storage systems
|Flooded Lead Acid||Sealed Lead Acid||Lithium|
-Operate from 5 to 7
-It needs external ventilation
To get rid of hydrogen gas.
-Operate from 3 to 5
-Does not require maintenance nor
-Operate more than 10 Years.
-Does not require maintenance nor
-Higher efficiency, faster charging
High usability (deeper
For more details read : 10 Best solar Batteries
In the second part i will talk about the last components of solar spumping systems which are :
#5 Well Pipes
They are joints between 5 and 6 linear meters and have no application or bends. The most material
Commonly is Low Carbon Steel and Galvanized Iron
And plastics (PVC), while the connections are made of screwing or welding in order to achieve the
Made of PVC to avoid rust problems and corrosion.
#6.Power supply cables
The submersible pump motor is electrically fed through a cable between the inverter outlet to the downhole. This means using a long cable. It is known that increasing the cable length leads to a voltage drop at the end of the cable, causing a Rise in the current drawn, which could lead to the combustion of the motor windings and to avoid this problem is used Cable of larger cross-section, preferably using cable tables manufacturers submersible pumps through which The appropriate section of the feeder cable is chosen according to the depth of the well.
Main cables used in three-phase submersible pumps with round or flat conductors (Figure (1) shows some types of Submersible pump cables.
Main cables used in three-phase submersible pumps with round or flat conductors (Figure (1) shows some types of Submersible pump cables.
#7 Water tanks
All solar water pumping systems use water tanks, to store water for several days instead
Of storing the electrical energy generated from the solar panel array, thus reducing system costs
The solar station (the battery component), i.e. the surplus water production is stored in the tank.
The water tank is classified according to use into:
- Plastic tank suitable for household use.
- َ Building ground tank, in which the floor and sides are isolated to prevent water leakagea heavy membrane can be used (one mm thick). This layer is laid on the floor and sides of the channels (Its end is buried with earth). Regular concrete is used to pour the floor and sides with thicknesses ranging between 10 & 7.5 cm, sides shall be angled no more than 45 °.
The depth of the reservoir should not be less than 2 meters to reduce the loss of water evaporation due to sunshine. In small projects, A tank is placed on top of a built roof (or a metal structure) or on a level higher than the ground to take advantage of the Gravity (and dispensing with a water pressure pump).
Classified by type to:
Open tank: The pump works when the sun rises and pumps water into the open tank (and distributes the water by gravity).
Pressure Tank :The pump is powered by batteries that are charged by solar modules. The pump works when it is running low
The pressure in the pressure tank, where the outlet of the pressure pump connects to the tank. The larger the tank, the smaller the number of stops and starts times of the pump, which increases the life of the pump, and reduces the sound from the operating cycle, Plus the pump runs more efficiently – and consumes less electrical energy. Typical pressure tank sizes T pressure ranges from 20 gallons to 100 gallons or more.
Generally, the general experimental method for determining the size of the reservoir is that at least 3 to 5 days of water use is sufficient The figure below It shows the shape of the components of an open tank system and a pressure tank.
Thank you so much , This is what you need to know about the main components of a solar pumping system see you in the next article