Transcript Solar_Powerx

Take Away Message
• The solar power system design is based on
technology flight-proven by NASA.
• We have been unable so far to obtain
measurements of the IR emissivity and Solar
Absorptivity of the solar panels.
• Power requirements adopted
• Preliminary for solar panel frames developed
• Power system is probably big enough
EUSO SPB Solar Power System
Jim Adams and Malek Mustafa
Adopted Power Demand
• Astronomical Night Load: 116.4 watts
– EUSO Telescope: 86.4 watts
– IR Camera: 30 watts
• Powered-down Load: 65 watts
– EUSO Telescope: 35 watts
– IR Camera: 30 watts
Please confirm these values
• Combined Efficiency of charging controllers & DC-DC
Convertors: 80%
– Night Load: 145.5 watts
– Day Load: 81.25 watts
• Required raw operating voltage: ~30 volts
Please confirm this voltage
 Maximum Power Demand: 3024 watt-hours/day
 Maximum Nighttime Power Demand: 2241 watt-hours/night
Solar Array
• Three SunCat Solar Panels per side
– Each Panel: 78.7 cm X 68.6 cm X 1.4 cm and 0.8 kg
– Expected power production - sun incident on only
one side:
• 415 watts at 25C
• 300 watts at 45C
• Power output is higher when sun strikes two
sides
– With two panels equally illuminated, the power
output will be 1.414 times larger that when one
side faces the sun.
Maximum and minimum power
production each day
• Minimum Power Production: 2500 watt-hours
– One side of the gondola always faces the sun squarely
so only one panel is illuminated
– The solar panel is operating at 45C
– Shortest day of the year
– 82% of maximum requirement
• Maximum Power Production 5213 watt-hours
– A corner of the gondola always faces the sun so that
two solar panels are equally illuminated.
– The solar panel is operating at 25C
– Longest day of the year
Battery Pack
• Batteries: Odyssey PC1200 lead-acid batteries
– These are flight-proven batteries recommended
by CSBF.
– We will use two 12V and one 6V battery in series
– Each battery each capacity of 42 amp-hours
– the string weighs 45 kg.
– We propose to fly strings of two batteries,
providing 2520 watt-hours of storage.
– Total battery mass will be 90 kg
What about the worst case?
(Solar Array falls 18% Short of meeting the Demand)
• This can occurs >60 days into the flight.
• If the gondola is rotating, the average production
will be 105% of the maximum even at 45C.
• If the solar cells are cooler more power is
produced (39% more at 25C)
• The battery capacity exceeds the maximum
nighttime demand by 12.5%.
• We need to sense the raw battery voltage
– If the raw voltage indicates 10% of stored energy
remains in the batteries, we need to switch to the day
time load, a 44% reduction in power consumption.
Power System Design
• Solar panels arrayed around the bottom of the
gondola – three panels on each side
– One charging controller for each side
• Two stings of Lead-acid batteries
Solar Array Crinoline
(open square frame)
Solar Array on Gondola
(Crinoline hangs at the bottom of gondola)
The End