1. Lunar Lander Power Systems
Adham Fakhry
Power Group
Lunar Descent Phase
[Adham Fakhry] [Power Group]

2. Solar cells for Lunar Lander
Ultraflex Solar cells
Ultra Triple Junction Cells
From Able Engineering
Efficiency = 30%
1000 $/Watt
150 W/kg
Mass = 1.57 kg
Power = 236 W
Area = 0.78 m2
Cost = $235,620
From Spectrolab
Efficiency = 28.3%
330 W/m2, 400 $/Watt (for 2kW – 5Kw range)
2.06 kg/m2
Mass = kg
Power = 218 W
Area = m2
Cost = $87,200
[Adham Fakhry] [Power Group]

3. Battery for Lunar Lander
To survive a Lunar night, need 5 W for standby power
145 W-hr/kg. Need 1680 W-hr to survive 14 days.
Need a 11.5 kg battery to meet this requirement, in order to survive the night.
Desired total mass of battery structure: 20 kg
(Insulation, Support Struts, Battery, Power Management and Distribution System)
Batteries obtained from Yardney – Technical Products.
[Adham Fakhry] [Power Group]

4. Backup Slide 1: Solar Array Grid
1.0 m
0.113 m
0.357 m m m
[Adham Fakhry] [Power Group]

5. Backup Slide 2: Power Sys. Prop.
Properties
Solar Cells
Batteries
Mass
1.362 kg
20 kg = 11.5 kg batteries + structure + Power Management and Distribution system
Power
218 W (Maximum potential power)
6,048,000 W or 1680 W-hrs
Cost
$ 87,200
Awaiting return from Yardney
[Adham Fakhry] [Power Group]

6. Backup slide 3: Battery Sizing
Calculation for battery:
Need 5 W for standby power
Mass Battery = 145 W-hrs/kg
Days of use = 14 days = 336 hrs
Usage = 5 X 336 = 1680 W-hrs
Mass = 1680 / 145 = 11.6 kg
Battery needs power distribution system, for managing power and dropping the voltage for other systems, such as camera, coolers, etc.
[Adham Fakhry] [Power Group]

7. Backup slide 4: Solar Array sizing
Solar array Calculations:
Dimensions of Solar cells:
Area of Lander roof = π(1/2)2 = m2
Solar efficiency = 300 W/m2
Potential max power = W
Cost of Solar Cells:
Cost of cells per watt = 1000 $/W
Cost of Cells = 235, = $235,600
[Adham Fakhry] [Power Group]

8. Backup slide 5: Solar Array sizing 2
Solar array Calculations:
Dimensions of Solar cells:
Total area = m2
Weight /area = 2.06 kg/m2
Total weight = kg
Cost of Solar Cells:
Cost of cells per Watt = 400 $/W
Cost of Cells = $ 87,200
[Adham Fakhry] [Power Group]

9. Backup slide 6: Cost per block
Solar array Calculations:
Cost of Solar Cells:
Cost of cells per block: $300 per block
Block sizes range from cm2 to cm2
Average number of blocks = 360
Total cost of solar cells = 70,200
[Adham Fakhry] [Power Group]

10. Backup slide 7: Potential Power
[Adham Fakhry] [Power Group]

11. Backup slide 8: References
[Adham Fakhry] [Power Group]