In many of the places we work, solar pumping is more economical than other power sources. It is particularly good when grid power is unreliable, and where managing diesel generators is a headache. Advantages include that solar pumping can be fully automated; there is no fuel to manage; and it is economical across much of the world.
Solar power is the preferred choice and the first option that all Oxfam projects should consider for off grid pumping.
Solar Pumping for Water Supply - The Book
Oxfam have been part of writing a book, which is a complete reference for solar powered pumping.
This book is based on five years’ work, including visiting over a hundred IDP and refugee camps and communities were visited in 12 different countries, during which hundreds of engineers were trained either in onsite events or via dedicated online training courses.
The book explains in simple and clear language not only the theoretical knowledge needed to understand the technology, but also the practicalities and lessons learnt relating to solar water pumping in humanitarian and development contexts.
It is also available in French:
Introduction to Solar Borehole Pumps
This Technical Brief is the best place to start. It introduces the different types of PV module, factors affecting solar energy production, where solar is viable, types of PV pumping systems, the components, sizing, costs and maintenance.
Global Solar Water Initiative
The Global Solar Water Initiative has created the Solar Hub, which provides many more resources, including case studies, guidance notes, and literature. A selection of key resources are below.
Solar kits from the Oxfam Supply centre
Two solar kits are available from the Oxfam Supply Centre:
A 3" pump for 4" boreholes, provides approximately 10 m³/day at 10-30 m total head.
Maximum flexibility for larger boreholes according to borehole yield, daily water demand, and available solar energy.
Planning & design
- Solar powered installations should be the first option for all off-grid water pumping projects.
- All solar installations should be properly designed, preferably using dedicated software.
- Systems should be sized to ensure there is enough water available during the worst time of year.
- Provision should be made for days when there is very low solar irradiation - either through accepting lower reliability (if other water sources are available), installation of a backup or hybrid power source (generator or grid connection), or appropriately sized backup water storage.
- Given the flow rate of water from solar powered pumping changes throughout the day, special consideration should be given to how chlorination or other water treatment will be undertaken. For example, a variable flow chlorine doser may be necessary.
- Where possible the system should be fully automated. This will increase system reliability.
- Always remember that even a single solar module is a live circuit that can result in electrocution. Fix all modules securely onto the support structure before doing any wiring and minimise the risk of accidents by covering and shading modules with their packaging until the installation is complete.
- All DC wiring should, if possible, be completed prior to installing a PV array. This will allow effective electrical
isolation of the DC system while the array is installed; and effective electrical isolation of the PV array while the inverter is installed.
- Solar modules consists of glass which can easily break. Do not throw objects at the solar module, stand or step on the module or try to repair your solar module if it breaks.
- Two or more modules connected in parallel or series if connected incorrectly to a pump can damage or destroy the equipment. Do not carry out modifications on your system without technical guidance from your system supplier or a qualified technician.
- Modules that have different characteristics in model, power, voltage and current should not be connected together in the same system (mismatching)
- Shadowing should be avoided as it leads to significant power loss.