Sizzling Water Utilisation Enhancer For Photo voltaic Water Heater

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The circuit offered right here is an easy system to reinforce the utilisation of sizzling water from a photo voltaic water heater system. Usually, throughout day time, you get sizzling water constantly from the photo voltaic water heater as a result of presence of daylight. However in absence of daylight, freshwater retains getting added to the tank and cools the water, which isn’t fascinating, particularly in winter. This isn’t a great way of utilising sizzling water at residence.

By controlling chilly water on the tank inlet within the absence of daylight, we are able to utilise the out there sizzling water in a greater method. This circuit is specifically designed to fulfil this requirement and could be put in within the current photo voltaic water heater by making some minor modifications.

The everyday block diagram of the photo voltaic water heater system is proven in Fig. 1. Sizzling water will get circulated by way of a photo voltaic collector, which collects warmth by absorbing daylight. This water is then saved in a storage tank, or piped into a further backup water heater tank. We’re going to add a solenoid valve at chilly water inlet in such a photo voltaic water heater system.

Block diagram of solar water heater system (Credit:
Fig. 1: Block diagram of photo voltaic water heater system (Credit score:

Circuit and dealing

The circuit diagram of the new water utilisation enhancer is proven in Fig. 2. It consists of Arduino Uno (Board1), LDR1 (gentle dependent resistor), 12V single changeover (1CO) relay, 12V solenoid valve, and some different elements. The circuit diagram of the ability provide is proven in Fig. 3.

Circuit diagram of hot water utilisation enhancer for solar water
Fig. 2: Circuit diagram of sizzling water utilisation enhancer for photo voltaic water
Circuit diagram of power supply
Fig. 3: Circuit diagram of energy provide

Arduino Uno

Arduino Uno board is related to LDR1, indicator LED1, and relay RL1. The sunshine depth learn by LDR1 is recorded and processed by the Arduino Uno board, which additional instructions the relay based on this system’s situation.

Energy provide

The ability provide is used to energy a 12V solenoid valve and relay (RL1) for switching. 5V DC can be derived from this energy provide. It consists of a 230V main to 15V AC, 1A secondary transformer (X1). The output of this step-down transformer is given to full-bridge rectifier BR1 and two capacitors of worth 1000µF, 35V (C1), and 1µF, 25V (C2). 12V regulator 7812 (IC1) and 5V regulator 7805 (IC2) are used for offering 12V and 5V regulated energy provides, respectively. Diodes D2 and D3 are supplied to forestall reverse polarity throughout connections. LED2 is a 12V DC indicator, and LED3 is a 5V DC indicator.

Light-dependent resistor

It’s related to analogue pin A0 of the Arduino board. LDR1 is used as a light-weight detector. The resistance of LDR1 decreases with the rise in gentle depth bombarded on it. In absence of sunshine, the resistance of LDR1 could attain up to a couple mega-ohms (M), whereas within the presence of sunshine, its resistance reduces to a couple ohms (). The discount in its inner resistance will increase conductivity.


Relay RL1 is an electromagnetic switching system, which supplies full electrical isolation between the controlling circuit and output circuit. It’s managed/triggered by a low DC. A 12V single-changeover relay is used right here to modify the solenoid valve on and off with using {an electrical} pulse.

Solenoid valve

Solenoid valve (SV) is an electrically operated valve. Mainly, there are two sorts of solenoid valves based on the operation state: usually open (NO) and usually closed (NC). These valves are used to regulate the circulation of fluid. If the circulation of fluid is stopped when the solenoid valve is energised, it’s a usually open (NO) solenoid valve. If the circulation of fluid is stopped when the solenoid is de-energised, it’s a usually closed (NC) solenoid valve. Right here, a 12V DC NC solenoid valve is used. The water flows when the solenoid is energised.


Arduino program (Utilization_enhancer.ino) is used for this prototype. This program code should be uploaded to Arduino Uno utilizing Arduino IDE. In this system, digital pin 13 of the Arduino board is outlined because the output. Its analogue pin A0 is used to learn analogue enter indicators. Some major capabilities of the Arduino code are defined beneath:


It configures the desired pin to behave both as an enter or output. See the outline of digital pins for the performance of the pins.


If any Arduino pin is configured as output with pinMode(), its voltage will likely be set to corresponding values: 5V (or 3.3V on 3.3V board) for prime and 0V (floor) for low.
Serial. It’s used for communication between the Arduino board and laptop or different units. All Arduino boards have no less than one serial port (also called UART or USART).


It units the information price in bits per second (baud) for serial knowledge transmission. For speaking with the pc, use considered one of these charges: 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, or 115200. You possibly can, nonetheless, specify different charges—for instance, you’ll be able to talk over pins zero and 1 with a element that requires a specific baud price.


It reads the worth from the desired analogue pin. The Arduino board comprises a multichannel, 10-bit analogue-to-digital converter. Which means that it’ll map enter voltages between zero and working voltage (5V or 3.3V) into integer values between zero and 1023.


It prints knowledge on the serial port as human-readable ASCII textual content adopted by a carriage return character.


It’s used to pause this system for the period of time (in milliseconds) specified as a parameter.

Development and testing

First, assemble the ability provide circuit. An actual-size PCB format for the ability provide part is proven in Fig. Four and its elements format in Fig. 5. After assembling the circuit on the PCB, join it with the Arduino Uno board, relay, and solenoid valve as proven in Fig. 1 through jumper/exterior wires.

PCB layout for power supply
Fig. 4: PCB format for energy provide
Components layout of the PCB
Fig. 5: Parts format of the PCB

Obtain PCB and Element Structure PDFs: click here

Earlier than assembling the primary circuit (Fig. 2) on a breadboard or any general-purpose PCB or veroboard, don’t forget to add the Arduino program code into the Arduino board.

As proven in the primary circuit in Fig. 2, a photoresistor (LDR1) is related between analogue (A0) and +5V pins of the Arduino Uno board. An NPN switching transistor 2N2222 (T1) is used to drive the solenoid valve by way of relay RL1. A 1N4007 diode (D1) is used as flywheel diode. The solenoid valve is related to the widespread terminal of relay RL1. It will get 12V DC energy supply by way of NC contact of the relay.

The solenoid valve is positioned at cold-water inlet of the photo voltaic water heater system to regulate the circulation of incoming water.

A floating valve could be put in on the inlet of the extra reserve/backup tank. It can cease incoming sizzling water when the reserve tank is full. The floating valve mechanically drops down when the water degree goes down.

The block diagram of the photo voltaic water heater system with the reserve tank and the floating valve is proven in Fig. 6. When sizzling water flows out from outlet of the tank, the chilly water begins getting into into the reserve tank. However throughout absence of daylight or at night time, the circuit prevents chilly water from flowing into the photo voltaic water heater tank by blocking the primary water inlet.

Block diagram of reserve tank with floating valve
Fig. 6: Block diagram of reserve tank with floating valve

On the identical time the out there sizzling water won’t be able to circulation into the reserve tank. So, a floating foot valve is required to maintain the outlet pipe sink in sizzling water.

Illustration of a typical floating foot valve is proven in Fig. 7. The floating ball will maintain the outlet pipe submerged to make sure uninterrupted water circulation.

Floating foot valve
Fig. 7: Floating foot valve (Credit score:

After wiring the entire circuit, join the ability provides (Fig. 3) to the primary circuit (Fig. 2) through CON1 and CON2 for 5V and 12V, respectively. Activate the ability provides.

The LDR1 will detect the depth of sunshine constantly. At day time, the sign at digital enter pin 13 of the Arduino is low. The low sign at pin 13 will maintain the relay (RL1) de-energised. So, the solenoid valve (SV) related to NC contact of the relay will get energised, permitting chilly water to circulation into the photo voltaic water heater tank. The recent water is additional saved within the reserve tank.

At night time, the circuit will give a excessive sign to pin 13 of Arduino, which can energise the relay (RL1). It will disconnect the solenoid valve (SV) from the 12V energy provide and cease the circulation of chilly water into the photo voltaic water heater tank.

Tej Vijaykumar Patel is B.E. in mechatronics and at the moment working as an engineer at SKAPS Industries India Pvt Ltd

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