One of the commonest questions we have in response to our article Solar Powered Irrigation is how to control mains pressure water fed irrigation systems – i.e. how to turn the water supply on and off automatically to feed porous pipe or drippers.

Digital Watering Timers and Valves

There are commercially available battery-powered programmable digital watering timer systems available which are quite affordable and reliable. The unit pictured above (Orbit Lawn & Garden Hose Digital Watering Timer and Valve) costs under £30 in the UK.

An easy to programme timer is connected to a solenoid valve which opens and closes at the set times. One end connects to the garden tap, and the other end to a standard diameter hose pipe which should in turn be connected to the irrigation system. Using Y-connectors it is possible to split the water supply to feed drippers, sprinklers, and porous pipe at the same time.

Buy an Automatic Watering Timer

Click here to search eBay for Watering Timers. They typically have a wide range of products from mechanical timers starting at just a few pounds, to advanced digital timers for £20-40.

DIY Automatic Watering Systems

There are situations in which an out-of-the-box timer valve will not meet the requirements of the user – for example, where a PIR motion sensor is to be used to detect cats and dogs to be repelled with a quick squirt from the sprinkler system, or where watering is required for a certain time after sunset (controlled by a light detector circuit).

In such situations, a solenoid valve must be used, typically switched by a relay controlled by a timer or other electronic circuit. Most solenoid valves designed for irrigation systems are 24 VDC powered which requires either a mains transformer, or a 24V battery bank.

Alternatives are available designed for automotive use, in caravans, in washing machines, and for ponds and other aquatics etc, and many of these are powered from 12 VDC making it much easier to power them from a single solar charged battery (or a cheap 12V mains transformer).

Again, eBay is an excellent place to find good value solenoid valves. The 12V solenoid valve pictured above the previous paragraph was offered recently for just £3.50 plus £2.00 postage in the UK.
Click here to search for Solenoid Valves now on eBay.