Solar PV water pumping study - FINAL REPORT ... - UNDP, Namibia

Feasibility Assessment for the Replacement of Diesel Pumps with Solar Pumps
FINAL REPORT: September 2006
The major service, overhauls and replacements is the responsibility of DRWS who provides
that service and pays for it.
It was found that this approach of handing ownership over to the community has increased
the life expectancy of water supply systems and reduced the abuse of systems.
The issues raised by the Directorate of Rural Water Supply with regards to community water
supply are as follows:
• Communities are familiar with diesel water pumps and are able to service and do
minor repairs on the engines locally.
• Communities require the flexibility in water consumption due to large herds of
livestock that graze in some areas of the communal areas.
• Diesel pumps installed through DRWS are usually designed for a ten hour pumping
day. That still leaves 14 hours for additional pumping if required.
• In the Kunene region people move the diesel engine to another site as they move
across the region to various grazing spots. The pipes, pumps and the discharge head
remain in the borehole and only the engine is moved. It is perceived that this cannot
be done with PVPs. Depending on the size of the installation and assuming no theft
prevention measures it would be quite possible to move the solar modules plus the
pump (assuming similar depth in other boreholes).
• Livestock herds have become so large in some areas that the water demand has
increased to such an extent that the diesel pump operates close to 24 hours a day.
The immediate priority is that the livestock receives water. DRWS is aware that the
large cattle herds present a long term problem for grazing, desertification and water
resources. However, it would be wrong to approach this through a limitation of the
water availability and will require a broader approach which addresses social, cultural
and economic issues within the community.
• Contractors for diesel pumps offer good support in the regions and make strong
efforts in terms of capacity building by providing free-of-charge training courses. This
is not perceived to be the case for the PVP sector where the service support seems
to revert back to Windhoek and where training of DRWS staff and community
operators is charged for by suppliers.
• DRWS is no longer supporting hybrid wind/diesel pumping systems and have phased
out these hybrids by converting them to either wind or diesel pumps only. The reason
for this is mainly economic/community affordability and reflects a policy of providing
one water supply solution. This too streamlines the maintenance support given by
DRWS.
In terms of PVP, the comments received from DRWS include:
• PVPs do not utilise boreholes to the full extent – a borehole with a safe yield of
5m 3 /hour will deliver more in 8 hours when pumped with a diesel engine than with a
PVP. The PVP delivers less water in the morning and the afternoon when demand is
at a peak. It is understood that tracking will provide a better utilisation factor but still
not the same capacity as diesel.
• PVPs cannot compete with DPs on boreholes with medium yield (2 to 5m 3 /hour) as
they can pump 24 hours a day. It needs to be understood that boreholes are often
operated at full safe yield for up to 24hours a day in order to meet the demand.
• DRWS has a limited annual development budget for water supply implementations.
The success of the regional heads in DRWS is “judged” by how many communities
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