how many wattts is the international space station solar system ?

[rollandelliott]

http://en.wikipedia.org/wiki/Electri..._Space_Station

doesn't mention it, Only clue I got was that it could powever several homes. So are we talking around 50KW or what?

What was really surprising was the panels are just 14% effcient. I thought nasa would be using something a lot more effcient.

[BB.]

A bit more information:

http://en.wikipedia.org/wiki/Integrated_Truss_Structure

Each of the Solar Array Wings are 34 m (112 ft) long by 12 m (39 ft) wide, and are capable of generating nearly 32.8 kW of DC power.^[4] They are split into two photovoltaic blankets, with the deployment mast in between. Each blanket has 16,400 silicon photovoltaic cells, each cell measuring 8 cm x 8 cm, grouped into 82 active panels, each consisting of 200 cells, with 4,100 diodes.^[3]

Not sure if 2/4/6/whatever "wings"...

-Bill

[SolaRevolution]

What was really surprising was the panels are just 14% effcient. I thought nasa would be using something a lot more effcient.

I wonder how many Watts/meter² they get at that altitude and, for that matter, how many hours per day? I would suspect they are harvesting far more than 140 Watts/meter² and quite possibly 24 hrs/day. The "extra terrestrial" PV array would not have the same operating tempurature considerations. I wonder how a normal STC flash test would compare to their "out-of-this-world" operating conditions. (First time I've used that phrase literally ) I imagine that they use a different rating system.

On Earth, a 2kw STC array which is 14% efficient by area, with 5 hours of noon sun may reasonably produce 8.5 kWh. Above the atmosphere a 2kW array which is 14% efficient by area could be much smaller and with 24hrs/day insolation it may produce as much as 48 kWh/day.

While it would be the ultimate in off-grid it may not require much of a battery bank.



-Alex

[SolaRevolution]

A bit more information:

http://en.wikipedia.org/wiki/Integrated_Truss_Structure


Each of the Solar Array Wings are 34 m (112 ft) long by 12 m (39 ft) wide, and are capable of generating nearly 32.8 kW of DC power.[4] They are split into two photovoltaic blankets, with the deployment mast in between. Each blanket has 16,400 silicon photovoltaic cells, each cell measuring 8 cm x 8 cm, grouped into 82 active panels, each consisting of 200 cells, with 4,100 diodes.[3

So, if you go by the area of the cells:

82 panels x 200 cells = 16400 cells
16400 cells x (8cm x 8cm) = 104.96 m²
32.8 kW / 104.96 m² = 312.5 W/m²

Assuming 14% cell area efficiency this would mean an orbital insolation of 2232 W/m² x 24hrs compared to 1000 W/m² for noon sun average on Earth.



-Alex

[bill von novak]

Assuming 14% cell area efficiency this would mean an orbital insolation of 2232 W/m² x 24hrs compared to 1000 W/m² for noon sun average on Earth.

I think it's closer to 14 hours. The station orbits the earth every 90 minutes so it's in shadow for a little less than half that time. The good news there is that the batteries only have to last for a "night" of about 36 minutes.

[techntrek]

The space station makes almost 16 orbits per day, and since it is in a low-altitude orbit it is in darkness for about half of each orbit - or about half of each day in total.

Edit: I see Bill had a similar post while I was composing mine.

[inetdog]

The space station makes almost 16 orbits per day, and since it is in a low-altitude orbit it is in darkness for about half of each orbit - or about half of each day in total.

Edit: I see Bill had a similar post while I was composing mine.

Is this a tracking array, independent of the orientation of the station, or is the whole station oriented to aim the cells?

[BB.]

From the Wiki Truss Structure link:

The Alpha joint is the main rotary joint allowing the solar arrays to track the sun; in nominal operation the alpha joint rotates by 360° each orbit (however, see also Night Glider mode). One Solar Alpha Rotary Joint (SARJ) is located between the P3 and P4 truss segments and the other is located between the S3 and S4 truss segments. When in operation, these joints continuously rotate to keep the solar array wings on the outboard truss segments oriented towards the Sun. Each SARJ is 10 feet in diameter, weighs approximately 2,500 pounds and can be rotated continuously using bearing assemblies and a servo control system. On both the port and starboard sides, all of the power flows through the Utility Transfer Assembly (UTA) in the SARJ. Roll ring assemblies allow transmission of data and power across the rotating interface so it never has to unwind. The SARJ was designed, built and tested by Lockheed Martin and its subcontractors.[

-Bill

[techntrek]

As Bill found, all of them are independently tracked arrays.

[rollandelliott]

I wonder what these solar panels are made of? The article mentions they had accidnets where panels "ripped" in the past. I bet they get really good performance in the coldness of space.