Health Clinic – Las Mercedes, Honduras

Janelle Barth, Stephanie Chang, Greer Mackebee, Walter Li

Structural Design

Current Footprint – 60’x80’

Notes - Footprint

• Cut and fill enough to fill hole without extra soil left over

• Strip footing• Soil – mostly clay• Minimum 5’ from boundaries• Allow space for latrine

Current Floor Plan

Notes - Plan

• Use spaces on exterior – optimize sunlight• Kitchen on right – minimize distance to latrine• Sink near shower – minimize piping• Delivery near kitchen for access to hot water (as

opposed to being connected to Recovery)• 8’ hallways for easy maneuverability (i.e. moving

beds, etc.)• 2 entrances – main (to waiting area) and kitchen

(to load supplies/easy access to latrine)

Other Notes

• Roof – corrugated tin and corrugated translucent material (optimize sunlight)

• 10’ walls• Materials: CMU (8”x8”x16”), rebar, poured

concrete base, wood beams for roof support system

• Sketch-up Model

Next steps

• Convert to metric• Determine optimal base depth for cut and fill• Design roof structure• Determine loads• Find North for solar panel/roof design

Standard Solar Powered System Design

Our System6 x Isofoton 75 Watt solar panel

Xantrex 40 amp + 30 amp charge controller

12 V 115 amp hr Nautlius deep cycle battery

WyckomarUV-250 UV water filters

3 x Low powered laptops

600 watt power inverter

Sunfrost Vaccine Refrigerator

Thin-Lite DC fluorescent lights

Location of Load componets

Battery /Charge Controller/InverterStorage

13 watt lights

30 watt lights

Vaccine Fridge

13 watt lights

13 watt lights/Laptops

Calculations for Total Power Consumption• Total power consumption =

Σ Appliance Wattage rating * Hours used/day*Total number of Appliance

Appliance Watts Hours /Day Quantity Total WattsSunfrost Vaccine Fridge

54 7.5 1 380

Thin-Lite 30 watts Fluorescent lights

30 6 3 540

Thin-Lite 13 watts Fluorescent lights

13 6 8 624

Laptops 8 4 3 96UV filter 30 4 1 120Total 1760

Sizing the solar panel

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

4.39 5.26 5.97 6.14 5.60 5.48 5.56 5.65 5.24 4.64 4.31 4.13

• Solar panels are tested at 1000 W/m at 25 ⁰ C • The solar panel should be able provide the required wattage at both the summer and winter

hours• For temperature ranges between 25⁰ and 40⁰ C, the power output is close to linear

http://www.reuk.co.uk/Effect-of-Temperature-on-Solar-Panels.htm]• 75 watt panels = 75/1000 = 0.075 % efficiency• At lowest solar isolation of 4.13 kWh/m2/day produces 4.13 * 0.075 = 310 watts per panel• Total number of panels needed = Total power consumption/watts per panel

= 1760/310 = 5.6 panels ≈ 6 panels minimumTo compensate for cloudy days and system losses, 7-8 solar panels may be necessary

Monthly Averaged Insolation Incident On A Horizontal Surface (kWh/m2/day)

Sizing the battery system• Nautilius Deep cycle are rated at 115 amp hrs and 12 volts for a total of

1380 watt hrs • Although deep cycles can be discharged to 80 %, they have a much larger

cycles is discharged at lower percentages• This is a graph comparing cycles of discharge vs. discharge %

• We want both a long lifespan for our system and also the power the solar fridge for several days if there are consecutive cloudy or rainy days/solar panel malfunctions

• Aiming for optimally 20 % discharge rate, each battery would be able to provide 0.2* 1380 = 276 Watt hours

• Number of batteries needed = Total wattage/ Watt hour per battery = 1760 /276 = 6.3 ≈ 7 batteries

• After 2 days, total watt hours available = (0.8)2 * 7 * 1380 = 6048 watt hrsThis can still provide 16 days of the vaccine fridge running by itself

• At 20% discharge rate, the batteries will last for 2500 cycles. • Assuming 1 cycle per day for each battery = 2500/365 = 6.8 years before

replacement. This will probably be 6 years, due to some over discharging.

Sizing the Charge controller• The charge controller prevents the batteries from

overcharging/discharging, maintains the rates of charging/discharging, keeps power from batteries from going back into solar panels, and also converts the variable voltage from the solar panels into a steady voltage

• For 75 watt solar panel, should be at 75 watts/12 volts = 6 amps, however this current can spike up to 8 amps. For our solar system, 7 * 8 amps = 56 amps. Thus we could use two charger controllers, a 40 amp and a 30 amp charge controller.

Sizing the Inverter• A 600 watt system will have enough capacity to power 5 amp tools, fans,

and also our needs for a water filter, and laptops. • The water filter = 30 watts • 3 laptops total = 24 watts • The 600 watt system will exceed our daily needs but will allow greater

expansion of AC appliances.

Choosing the laptop • Netbooks are very power efficient• The Dell mini 9 makes if easy to upgrade RAM and hard drive• The solid-state hard drive is less likely to fail• Linux drive Operating System can be re-installed and rebooted from a USB

drive, and thus making system recovery very easy

Choosing the Vaccine Fridge

• Sunfrost energy specifications• Energy Consumption (12 volt) making 2.2 kg ice/day

.38 kWh/day @ 32° C (90° F)

Running Current: 4.5 amps for 12 volt system, 2.3 amps for 24 volt system Starting Current: 15 amps for 12 volt system, 7.5 amps for 24 volt system

Room Temperature 21° C (70° F) 32° C (90° F) 43° C (110° F)

Refrigerator Temperature 3° C (38° F) 3° C (38° F) 3° C (38° F)

Freezer Temperature -11° C (12° F) -9° C (15° F) -5° C (23° F)

• The Sunfrost Fridge:– has been approved by the World Health

Organization– is very power efficient– can maintain a fridge temperature of 3° C at a

large range of temperatures