Solar-powered irrigation with timer

Motivation

I want to ensure that my garden is watered during hot days in spring & summer and while on holiday. This solar-powered irrigation device means that water is used efficiently and I can set the timer as needed. It is purposefully as low-tech as possible (no IoT).

System schematics

The overall schematic of the system is shown below: the solar panel power the battery via the charge controller; the pump is powered via the timer relay switch. Everything operates at the 12 V of the battery.

There is no power in the relay (pump) circuit, so this is transferred from the load circuit of the charge controller.

Implementation

All items are wired up as per the schematic. Depending on the crocodile clips that come with the solar panel and the internal height of the box, you may need to solder smaller/lower profile crocodile clips on the cables.

All electrical items are placed inside the waterproof box, with the cable for the solar panel (input) and to the pump going through the weatherproof penetration.

Set the timer to the desired setting (time unit and timer profile, e.g. relay on/off switching). Connect the perforated hose to the submersible pump and place it inside a water butt.

Now all you have to do is wait for the timer to kick in & the plants to be watered.

Further work

As well as a timer relay, it would be useful to integrate a simple soil moisture sensor as a second relay in the pump circuit.