Guidance note on the use of solar pumping
Rationale for the use of solar PV pumping solutions
The factors mentioned in section 1.2 make conditions ripe for solar pumping to be considered as a default option for water provision in places with medium to high levels of solar irradiation (4–8 kWh/m2), especially in off-grid locations, long-term camp contexts, or where water supply is fuel dependent but the fuel supply is too costly or erratic.
The presence of some trained private-sector contractors with good-quality solar pumping equipment in many countries further supports solar uptake and can be counted on by relief and development organizations to facilitate adoption of solar solutions for water supply projects.
There is a high potential for cost reductions to be realized if analysis and funding decisions are based on costs over the life cycle of schemes costs over time), rather than only considering capital costs of installation.
In addition, environmental considerations make solar pumping technology a climate-smart choice, especially when considered against any diesel-based option.
Camp contexts: mainstreaming of solar pumping
In camp contexts with the prospect of being in place for more than two to three years, solar pumping should be considered as a default solution. It should be considered from as early a stage as possible, whenever solar pumping solutions are able to meet a significant amount of
the water demand (GLOSWI, 2018b). Stand-alone solar systems should be favoured over hybrids (solar + diesel generator or other back-up power source) because of their higher
cost-saving opportunity and simplicity of operation and maintenance. However, care should be taken whenever a rapid change in context could translate into longer pumping hours going beyond the solar day, for example, when population figures are not well known or are prone to sudden increases at short notice (e.g. large refugee inflows), or when the behaviour of the aquifer is largely unknown (e.g. unknown safe pumping yields or possibility of large variations in drawdown over the seasons). In these cases, a back-up power source should be considered so that pumping beyond the solar day is possible if needed.
In older camps, solarization of water schemes should be prioritized to ensure water provision, looking first at camps with high recurrent costs or with high water shortages due to irregular or nonexistent electricity or fuel supply to power water pumps.
Host community context: social aspects before technology choice
Solar pumping is, from the technical point of view, equally appropriate for water supply projects at host community level (villages and towns) as for refugee or internally displaced people camps. It should be considered as a default option, in order to increase sustainability and resilience of communities. In contrast to camps where there is normally a permanent presence of relief organizations, aspects to do with ownership, operation, and maintenance add an extra layer of complexity in the host community context.
At host community level, adjustments related to the collection and use of water fees will need to be introduced and discussed, as solar solutions may not require a constant inflow of funds to operate and it may take years before equipment breaks down. Therefore, the narrative of solar-powered water systems for communities should shift from ‘tapping into a cost-free source of energy to pump water’ to ‘accumulating funds for system replacement’.
A well-thought social approach, involving contribution from users and external technical support for maintenance and repair should come before technology choice. In this sense, prioritizing communities with strong social cohesion and coordinating approaches with government water offices and/or knowledgeable private-sector companies is a prerequisite.
When solar pumping should be discouraged
Solar pumping should not be seen as a blanket solution to every water supply project and its use is discouraged in some cases, namely:
- where theft and/or vandalism of solar pumping schemes is widespread, as reported from past interventions;
- when the expertise of the implementing organization is low and private- sector support cannot be counted upon;
- where solar technology does not bring any significant technical, economic, or enviromental advantage over existing solutions in terms of amount of water supplied, greenhouse gas emission reduction, cost savings over time, or simplicity of operation and maintenance of equipment.
Issues related to operation and maintenance, and training and evaluation
Solar pumping schemes will suffer fewer breakdowns and have much less intensive maintenance than generator or hand pump schemes. However, solar pumping schemes can and will experience technical problems at some point in time that cannot be solved at community level (or for which the organization in charge of the water scheme will probably need external support), regardless of the training provided in the past.
It is important that service agreements are established with a good- quality private contractor, water utility, water service provider, or relevant government technical office, before any installation and they should be renewed as needed.
Since the single most important barrier towards a wider adoption of solar pumping solutions is the weak technical expertise of most WASH organizations, support from the private sector, government, and/or the donor community should be provided or encouraged for capacity-building activities in areas with high potential for adoption of solar pumping solutions (e.g. areas with high solar radiation and high dependency on fuel-based solutions for the supply of water).
In addition, ways of collaborating (with, for example, academic institutions, knowledgeable private companies, or water utilities) should be encouraged in order to make training activities as sustainable or over as long a duration as possible.
Finally, since adoption of solar pumping solutions is often based on the long life expectancy of solar products, it is important to support evaluations of older (more than five years) solar systems in order to build up stronger evidence on the adequacy of solar pumping technology for the given context, as well as to inform future water strategies in the country of work.