Category: Handpump Technology

By Andrew Armstrong (Water Mission), RWSN co-lead for Sustainable Groundwater Development

Solar pumping is the trendiest technology in rural water supply today. Policy-makers and practitioners are eager to better understand its benefits and limitations and the private sector is responding with a variety of product offerings. Much of this interest is motivated by the Sustainable Development Goal to increase water service levels in the most remote areas. A more compelling driver is that rural water users are willing to pay for service that is accessible near or within their homes. There is currently no more promising technology for meeting these expectations in off-grid settings than solar pumping. Despite this high interest and the fact that solar pumping technology has been around for decades, a great deal of misinformation is being propagated.

This post aims to address a few of the most common misconceptions.

Myth #1: Solar pumping is too complicated and not appropriate for remote, rural settings

The most common barrier to adoption of solar pumping is misunderstanding of its complexity and applicability. The technology is often avoided because of perceived technical and management challenges, which are in fact common to any rural water supply system. In reality, the design and installation processes associated with solar pumping are no more complicated than other motorized pumping schemes. Operation and maintenance is more straightforward than with handpumps and generator powered schemes which, as indicated in recent evaluations published by UNICEF and the Global Solar and Water Initiative, likely leads to higher functionality and reliability rates.

Solar pumps are applicable across the same head and flow profiles as grid- and generator-powered pumps, and most solar pumping equipment available today is essentially “plug and play”. External power backup for periods of low sunlight are rarely necessary if water demand is estimated and storage is sized appropriately. In addition, current off-the-shelf computer software tools simplify equipment selection and automatically consider daily and seasonal weather and solar irradiation fluctuations when estimating water outputs.

The high capital cost of solar pumping equipment often brings its large-scale applicability into question. However, the life-cycle cost benefits of solar pumping are well documented and are within and on the lower end  of IRC’s WASHCost benchmark ranges for piped schemes and boreholes fitted with handpumps. There is no fuel cost associated with solar pumps, and the cost of maintaining power generation equipment is greatly reduced because solar modules have no moving parts and long functional lifespans. Furthermore, the cost of solar modules, which represent the most expensive element of a solar pumping scheme, continues to decrease at a rapid rate.

Myth #2: All solar powered water pumping equipment is created equal

Equipment manufacturers have taken advantage of demand and have flooded the market with solar pumping products of all varieties and price tags. Unfortunately, many are of poor quality and likely to fail in a fraction of the lifespan of higher priced, higher quality equipment. Low-quality products seldom come with warranties covering the first few years of operation during which failures are most likely to occur. Uninformed customers often fall into the trap of choosing cheaper equipment without considering that low-quality equipment fails quicker and costs more to maintain in the long-term. This results in solar pumping schemes which were expected to function for years failing and being abandoned after a few months in operation. The best way to guard against this is to stick with brands that have a proven track record for durability and reliability, even if it costs more up-front. It is also important to verify that products adhere to internationally-recognized certification and testing standards.

Another related challenge is that imitation spare parts for major brands are easier to find than authentic ones. Logos and barcodes can be forged such that it becomes difficult to detect if a part is counterfeit. This issue can be resolved by sourcing products from trusted dealers with good technical support capacity. The private sector can also have a positive influence on product quality. By providing local dealers with exclusive access to advanced training and support networks, major manufacturers can incentivize sales of quality equipment. In fact, some solar pumping suppliers such as Bluezone Malawi  are choosing to base their business model solely on high-quality products.

Myth #3: Scaling-up solar powered water pumping will lead to widescale depletion of groundwater aquifers

There is concern that solar pumps, because they can operate automatically whenever the sun shines, could pose a long-term threat to groundwater resources. It is true that exploitation of groundwater paired with low or misunderstood aquifer recharge can lead to potentially irreversible depletion, and there is a deficiency of good hydrogeological data in countries where the most interest is being placed on solar pumping. However, abstraction technology is just one of many factors that influence aquifer sustainability and solar pumping should not be devalued because of potential risks which can be mitigated. It is also important to note that the risk of groundwater depletion due to over abstraction with solar pumps depends on the application. Domestic supply withdrawals, in comparison to agriculture and protracted emergency applications, are likely to have negligible impacts.

Below are some actions that can be taken to mitigate the risk of groundwater depletion:

• Proper borehole development and pump sizing to safe yield – Ensures solar pumps are physically incapable of depleting aquifers. A good resource for this is the RWSN/UNICEF Guidance Note on Professional Water Well Drilling. Simple control measures such as float valves and switches can also be employed to prevent wasting.
• Better groundwater monitoring alerts authorities to potential risk areas. Many countries successfully employ remote monitoring systems (see, for example, the USGS’s National Groundwater Monitoring Network. Read more here.
• Water pricing in the form of tariff collections and abstraction charges enables sustainable and equitable allocation of groundwater resources, but requires sound management built on transparency and accountability. Prepaid water metering technologies may also play a role.

Further resources

Resources are available to equip rural water professionals with knowledge and skills and stop the spread of misinformation about solar pumping. Of note:

• The World Bank curates a solar pumping website and knowledge base. For a good overview of solar pumping system components and other considerations, see this recent World Bank publication (Solar Pumping: The Basics).
• The Grundfos Technical Institute offers a series of free pre-recorded solar pumping and related webinars.
• Numerous universities, such as Strathmore University in Kenya, offer in-person courses designed specifically for working professionals.

In order to generate rich discussion and continue raising awareness of existing resources around solar pumping, the RWSN Sustainable Groundwater Development theme will host a three-week e-discussion from 28 May to 15 June 2018. For more information or to participate in the e-discussion, join the RWSN Sustainable Groundwater Development DGroup.

(Photo credits: Water Mission)