| Traditionally the water pumping technology of choice | | | | 5: Some of the pump models can be backed-up by a |
| has been the wind pump. Wind pumps provide long | | | | genset to pump additional water with the same |
| lasting solutions with a basic technology which is well | | | | pump during the night or during overcast days; |
| understood and can be maintained locally. However | | | | 6: Good quality and reliability. |
| even wind pumps have become expensive to install | | | | 7: Simple to install: Furthermore, solar pumps are well |
| and to replace. | | | | known for having the following features: |
| Solar water pumps and dc pumps are currently being | | | | 8: Require minimal attention as they are self-starting; |
| used to irrigate crops, water livestock, and provide | | | | 9: Solar pumps are “good” for boreholes as |
| potable drinking water. Solar water pump uses peak | | | | they pump over the whole day; |
| solar array output which frequently coincides with | | | | 10: Weak boreholes can be used effectively with a |
| high water demand during long, dry summer days. In | | | | low volume pump due to pumping 8 to |
| the event of cloudy weather solar water pump | | | | 10 hours a day; |
| systems often use storage tanks to store excess | | | | 11: In most cases, a solar pump offers an ideal |
| water. Unlike generator powered water pumping | | | | solution to the diesel option which requires operating |
| systems, solar water pumps do not require fuel or | | | | funds (with uncertainty about future diesel prices), |
| constant maintenance. Solar water pumps can also be | | | | time investment for operating pump (manual starting |
| designed for portability to be moved as water | | | | etc) and logistics for fuel, maintenance, installation and |
| demand or change of seasons requires. Solar water | | | | de-installation; |
| pumps cost less to operate, offer modular capability | | | | 12: Tracking arrays can be used to increase daily |
| to be quickly expanded as demand increases, unlike a | | | | water pumping rates; |
| generator or windmill water pumps. | | | | 13: Solar pumps offer clean solutions with no danger |
| Diesel water pumping is attractive due to the large | | | | of borehole contamination. |
| power range of the pumps and the availability of | | | | Theft of solar photovoltaic panels is a problem and |
| water when it is needed. It can pump water for | | | | one needs to look at counter measures if there is a |
| varying daily demands through longer operating | | | | risk of theft. Refer to web links below for more |
| periods (assuming sufficient borehole strength), thus | | | | information. |
| allowing for the flexibility required in some applications. | | | | Cost of solar and diesel pumps: |
| The technology is well understood and service for | | | | A cost comparison was conducted for solar and |
| diesel engines is readily available. Recent fuel price | | | | diesel water pumps over a range of pumping heads |
| increases and generally intensive maintenance | | | | (10 to 200m) and a range of daily flow rates (3 to |
| schedules however can make diesel water pumps a | | | | 50m3/day). The all-inclusive costs were calculated |
| costly pumping option. | | | | taking into account. |
| Solar water pumps are often thought of as being an | | | | The initial upfront cost, the operating costs (diesel |
| expensive technology, which is not able to pump | | | | fuel for the operating life), maintenance costs, and |
| enough water and which is not durable. | | | | ?replacement costs (diesel engine, solar submersible |
| However, solar water pumps have come a long way | | | | pump unit etc).Calculating the all-inclusive cost is a fair |
| in 25 years and today there are solar pumps on the | | | | way of comparing solar pumps (usually higher upfront |
| market which have improved on previous technology. | | | | cost) with a diesel pump (usually lower upfront cost, |
| 1: Submersible pumps which can pump up to 200m | | | | but with ongoing diesel and intensive maintenance |
| heads; | | | | costs). The all-inclusive cost takes a long term |
| 2: Pumps that are able to pump larger volumes of | | | | approach and is calculated over a twenty year |
| water, e.g.: | | | | period, which is also the minimum life expectancy of |
| At 100m, about 10,000 liters per day; | | | | a solar panel. The cost comparisons show that diesel |
| At 50m, about 20,000 liters per day; | | | | pumps are on average two to four times more |
| Above performance can be doubled through dual | | | | expensive over a 20 year period than solar pumps |
| systems (if the borehole allows his). | | | | for pumping the same average amount of water per |
| 3: Low maintenance requirements (3 to 5 years). | | | | day! Refer to costing approach in final report for |
| 4: Good performance which means fewer solar | | | | more detailed information. |
| panels to pump the same amount of Water. | | | | |