1. Engineers Without Borders-USA 2008 International Conference

2. University of Minnesota Chapter Solar-Powered Well Pump and Water Tower Amponsah, Ghana Spring ’06 to Summer ‘07

3. Agenda Community Needs Site Visit Design Implementation Challenges

4. Community Needs 600+ students & villagers w/o clean water Pit latrines w/o wash station Result:  Lost time in class due to diarrheal illness  Gender inequality from fetching water  Rare but still present: Guinea Worm

5. Site Visit - Summer 2006

6. Village Above-ground water tower Grundfos submersible pump M/F sanitary toilets Hand washing station Biomass compost pens Soccer field / P.E. field Irrigated farmland for school crops main school building drying slab for crops and bricks secondary classrooms secondary classrooms Control Box water line Solar panel array water faucet Design Layout

7. Pump Grundfos SQFlex-11  11GPM  30-300 VDC / 90-240 VAC  Multiple Protections

8. Solar Array 8 Panel Array BP 3115J, 115 W 12 V, 7 A Nominal

9. Implementation- Summer 2007

10. Raising the Water Tank

11. Implementation

12. Perfect or Far From? Major Challenges: 1 Transport 2 Wrong Tower 3 Incorrect Schematics 4 Well Log Inaccurate

13. Challenge 1: Shipping

14. Challenge 2: Tower Main structure after our modifications Structure present when team arrived 10 ft Seal Welds Added Cross-Bracing Added Footings w/ Rebar

15.  Max exposure to the sun  Above jungle canopy  Reduced potential of theft 6500 L Polytank (10L/person /day) Challenge 2: Tower

17. Designs are often modified in the field -- previous structural/failure analysis is no longer accurate Design failures occur despite the strength of your materials 3D FVM study of 80 fps (59 mph) wind gust directed towards the lofted edge of the solar panel assembly - to be coupled with structural analysis to determine strains on mounting brackets. necessary to prevent catastrophic accidents Retroactive Design Analysis Failure analysis can direct your in- country collaborator’s attention to features prone to failure

18. Challenge 3: Incorrect Schematics 2 Parallel 4-Panel Banks8 Panels in Series Result: 125 Watts in full cloud cover Result: Random pump shut-off in 50% sunlight 48 V 96 V 48V @ 14 A = 672 watts96V @ 7 A = 672 watts

19. Challenge 4: Well Performance Valve to limit well output Pump Duty Cycle: 5 Gpm Lockout 2 Gpm We had to limit well output due to incorrect well log ( = pumping, =Low Well Alarm) Time

20. Concluding Remarks

21. Contact Information Presenter: Nathan Knutson knut0293@umn.edu Chapter: www.tc.umn.edu/~ewb President: Brian Bell bell0384@umn.edubell0384@umn.edu