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
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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
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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 System
6 x Isofoton 75 Watt solar panel
WyckomarUV-250
UV water filters
600 watt power
inverter
Xantrex
40 amp +
30 amp
charge
controller
12 V 115 amp hr
Nautlius deep cycle
battery
3 x Low
powered
laptops
Sunfrost Vaccine
Refrigerator
Thin-Lite DC fluorescent
lights
Location of Load componets
30 watt lights
13 watt lights
13 watt lights
Battery /Charge
Controller/Inverter
Storage
Vaccine
Fridge
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 Watts
Sunfrost 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
96
UV filter
30
4
1
120
Total
1760
Sizing the solar panel
Monthly Averaged Insolation Incident On A Horizontal Surface (kWh/m2/day)
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
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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 minimum
To compensate for cloudy days and system losses, 7-8 solar
panels may be necessary
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 hrs
This 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
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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)
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)
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
• 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