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DIY Solar Water Switch using Cycle Timer Delay Relay Module

There are a lot of benefits from planting greenery in your garden. Besides having it as a hobby, it can enhance your patience and endurance. Planting trees not only can reduce carbon footprint, it also can provide shade and cooling to your house and surrounding. Fruit and vegetable plant may also provide you nutritious food and be self sustained while flower plants could bring fragrance and increase aesthetic value to your house. If you like gardening perhaps you may need to continue reading this post. 

Planting greenery may requires long term commitment such as regular watering, weed & insects removing and fertilizer. Watering is the most crucial action which need to be done every one or two days especially in hot countries or hot seasons. Because of the daily commitment, you are being tied to the schedule and not willing to go longer vacation or travelling worrying those plants might dried and die.  

There are many self watering systems in the market which you can set the timer when you want the watering system to be activated. The duration for each time watering operation can also be set by user. All you need is to add the timer water switch in between the water pipe and water outlet.

Electronic Water Timer Switch

Electronic Water Timer Switch allows user to set exactly what time the watering is operating. User can also set the time duration for each watering operation and also can set which days in a weekly basis. You can get it at our affiliate link here !!!

Garden Hose Adapter & Accessories 

Remember to purchase relevant garden hose accessories as well so that the hose can fit into the Electronic Water Timer Switch. You can get it cheap at our affiliate link here !!! 

Today we would like to talk about DIY Solar PV operated water switch. If you are good in DIY, perhaps this is another weekend project for you. Commercial water timer switch got 1 main disadvantage; all of them are battery operated. As you know, battery under sunlight would not last long. Whenever the battery is replaced, the Real Timer Clock and all the setting function have to be reset again. I hate this process !! You must keep the manual of the water switch timer all the time or else you will run crazy on how to set it again.

DIY Solar PV operated water switch although has high invested capital cost, it will be worry-free and no maintenance compared to commercial type water timer switch. You need a Solar Panel, a Water Switch, a Timer Delay Relay Module, and a DC-DC converter.

20-30Wp Solar Panel 18Vmp

A good quality of Solar Panel can last more than 20 years. It is a portable and convenient power source suitable for small application such as Water Switch. You may consider getting one at our affiliate link here !!!

Trigger Cycle Delay Timer Switch Module

This is one of the most powerful and flexible delay relay suitable for many electronic and electrical projects. One of the uses can be used to program cycle operation which suitable in watering system. Support us by purchase the unit at our affiliate link here !!!

12V Electric Solenoid Valve

12V electric Solenoid Valve using electromagnetic mechanism to pull the valve gate up for water to flow when in operation. If no power supply, the water is stopped by the valve. You may get one at our Aliexpress affiliate link here !!! 

The overall concept and process would be using Solar Panel to provide power to the Cycle Delay Relay Switch module. The Switch module has a wide acceptance voltage range within 5 to 36V thus using a standard 18Vmp Solar Panel is acceptable without any voltage regulation. When the time recording is reached, it provides power to the 12V Electric Solenoid Valve via a DC buck converter for voltage regulation. 

The whole system does not require any batteries as the program is permanently stored in the Switch module just like Arduino Micro Controller board without need to worry re-program if power is lost every night. Below is the overall wiring diagram of the circuit.

2 Pin Waterproof Connector

It is the waterproof connector which is suitable to be used outdoor. It can connect up to 1..5mm square cable size. Grab a set of connector at our affiliate link here !!!

2 core 1.5mmsq Flexible Cable

Flexible cable is a synthetic rubber cable mostly used in portable tools such as hand drill or welding cable. It is made flexible and reasonably good resistant against outdoor and weather. Try surf and compare them at our affiliate link here !!!

DC-DC Buck Converter Module

DC to DC buck converter allows a wide range of DC input voltage to be step down and regulated to desired output voltage. It mostly applied on Solar DC direct application. You may need a multimeter to measure the voltage output by adjusting the trimpot. Grab one at our affiliate link here !!!

Ferrule Lugs and Crimper Set

Ferrule lugs are used at terminals for tight and secure connection. Besides, it also prevent stranded cables accidentally touching adjacent power line that may cause short circuit. Grab 1 at our affiliate link here !!!

Specific Working Mode of the Cycle Trigger Delay Relay Module:

P3.2 setting mode – When power is on, Output keep ON for OP (operation time) and then OFF for CL (close time) and then the cycle is keep on looping. The number of cycle or set can be set, but we will set it as infinity. No input signal triggering is needed. 

How to set Delay Relay Module:


Long Press = press and hold it for at least 3 seconds then released. Short Press = press and release your hand.

  1. Supply Power to the Relay Module.
  2. Long Press the SET button. When hand is released, it will show current PX.X mode.
  3. Press UP or Down button to reach P3.2.
  4. Short Press the SET button. OP word will be blinking. It is used to set ON (operation time duration). 
  5. Short Press STOP button to Switch between time frame. “XXX.” is for time in 1 – 999 seconds range, “XX.X” is for 0.1 – 99.9 seconds, “X.X.X” is for 1 – 999 minutes range.  
  6. Press UP or Down to set the OP time that you want then Short Press the SET button. CL word will be blinking. It is used to set OFF (closing time duration).
  7. Short Press the SET button. LOP word will be blinking. It is used to set number of cycles. Set it to “- – -“ for infinity looping 
  8. If everything ready, Long Press the SET button to save the parameters.

UNI-T Multimeter is a good quality with decent price. We have been using UNI-T multimeter for years has not been any issue. We were using UT33C model. It can measure RMS Voltage. You can get yours at our affiliate link here !!!

At the moment when supply power applied to the module, the delay relay will turned on and start to turn on the load straight away for time counting. In the very beginning of the day when solar power is too weak, you may expect it will keep restart and shutdown until when power is strong enough. It will be normal.

In summary, Solar Operated self watering system may be more expensive for its capital cost and require some DIY work. Once everything done, it will be just no need to worry about replacing battery and reprogram the timer during battery replacement. It is purely subject to sunlight, which when sunlight is low, no water might be out. It also may be good because sometimes cloudy or raining does not require much watering to the plant. 

If your water switch does not work all the time, you may be have to up size your solar panel capacity. Based on calculation and project in the video, a half inch pipe and solenoid valve can be supported by 25Wp Solar Panel without any issue.

Terminals Crimping Plier Set

This is a crimping tool with interchangeable jaw for crimping many types of terminals. It is a must have for DIY electronic and electrical for professional installation work. You may choose at out affiliate link here !!!

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