Solar irrigation project

A new commission from Hackney City Farm.

The brief

Use existing equipment to make a solar powered on-demand pump for the poly tunnel at HCF
Use low power LCD modules that give readout of: battery voltage, litres pumped, kW/H saved etc. Have the same information displayed inside straw bale.
Use a level meter to determine if there is water available.
Make sure the system can be expanded to make use of a secondary water butt.

solar panel and charge controller charge a 12V lead acid battery on the roof. This is in place already.
an on-demand pump is connected between the water butt and the poly tunnel.
the microprocessor measures the current drawn to determine if the pump is on,
the microprocessor measures the time the pump is running and uses this to work out:
- kW/H saved,
- litres water pumped,
this information is displayed on an LCD module outside, and also one inside.

The idea is that if there is an excess of water, instead of wasting it we can pump it to another butt located near the poly tunnel.

This could be done with:

a manual switch to choose where to pump the water,
an automatic solution that uses solenoid operated valves (we have a few already) and a level sensor.