PV Gap

Tommy Said:

PowerSat : Space Solar Power - is it for real?

We Answered:

I remember hearing this idea in 1980, and at the time, it was thought this might someday be practical.

The day has not yet come. It's very expensive to put even small satellites in high orbit. As a crude example, a shuttle flight costs about $1 billion, and I'm being generous. Taking the panels on my roof as an example, lets say you get 6 watts per pound out of them. We'll say the shuttle can take 2 tons up, so that's 24,000 watts, if I'm figuring right. Let's say, with round numbers, that those panels cost $100,000. For that same money, you could get 10,000 times as much power, just by keeping the panels on earth.

Judith Said:

Why is solar technology so costly?

We Answered:

You are right that it would be a combination of cumbersome and costly to use solar energy for many things.

Solar cells are made using semiconductor manufacturing technology. The machines used to precisely control the manufacture of this material can cost 10s of millions dollars a piece. The same material - used to make a computer chip - can cost up to $1000 per square inch once fully processed into the fastest microprocessors. Thankfully, soar cells are a bit easier to make than these high speed microprocessors and as a result are much cheaper.

Even on a bight sunny day, one fundamental limit of solar technology is the limitation of the power available from solar energy in a given amount of area. For example the amount of energy that shines on the surface of a car parked in the sun at noon on a sunny day is still not enough to move a typical car up even a small incline, must less send it speeding up a steep hill at 60 miles per hour.

Add to this, the problem that even the most expensive solar energy cells lose most of the sun's energy during the conversion process and also that the sun just doesn't shine that much (remember night time, right?). So, to obtain enough energy to supply powerful items like cars, one must either fill a very large area with solar collectors (expensive and not practical for your typical road) or let a solar panel charge a battery for a very long time, just to move a car for a short time.

Conversely, your vision has arrived in for many items. Solar powered radios, road signs, calculators, off-shore beacons all exist. Some yatchs use solar power to power the whole ship. Hey, my watch is solared powered!

Jack Said:

35. When will the technology exist for solar power stations in orbit?

We Answered:

It's hard to answer questions like this because of the uncertainty of the development schedules and priorities of developing these technologies.

About the only intelligent response I can give you relates to the major challenge of achieving this goal. --namely, how do you get the power from space to the earth.

Of course, as I'm sure you know, nearly every satellite in orbit relies on solar power to generate electricity, but none of them beam the power to earth. The major issue with tranmitting that power to earth? Microwaves seem to be the answer, but what do you do about the area in the atmosphere that would create a dead zone through which nothing could pass.

James Said:

why don't we use solar power when we have the technology do governments really care about the enviroment?

We Answered:

To much tax on fuel and not everyone has alot of sun

Ron Said:

solar powered technology?

We Answered:

Because Hawaii has a lot of sun, our solar powered phones are located on the side of roads in case someone has car trouble.

We also have combination solar/wind generator lights installed at the Hanauma Bay parking lot.