Solar

The sun doesn't shine all the time. Besides the problem with night and day, there is also the problem with cloudy days. And if the panel is not positioned at a right angle to the sun's rays, the efficiency drops - and the angle of the sun's rays changes continuously, so for ideal results, the panel needs to be repositioned continuously. Bottom line: on average, solar panels will only deliver about 16% of their rated capacity. Therefore, it would seem unwise to depend on solar for more than one-sixth of one's power needs.

Under ideal conditions a single 8.75 sq ft Sharp Solar Panel will generate 175 watts. Each 175 watt Sharp solar panel costs $520 when purchased in bulk.

 

For Future Cost Comparison

How many 175 watt solar panels would be required to replace just one-sixth of the 12,900,000,000,000 watts (12.9 Terawatts), presently produced from carbon-based fuels every hour here on Earth, assuming that the solar panels are operating at 16% (0.16) efficiency? And how much would it cost for that many solar panels?

2,150,000,000,000 watts/(175 watts per panel x 0.16) = 76,800,000,000 panels

Each panel costs about $520.

$520/solar panel x 76,800,000,000 panels = $40,000,000,000,000

Excuse me? $40 TRILLION dollars???? For just one-sixth of our energy need???

It's a pretty scary number, but just for future comparison purposes, to eventually put this number into perspective, let's calculate the cost per Terawatt:

$40 Trillion/2.15 Terawatts = $18.6 Trillion/Terawatt (remember this number!)

Umm… $40 TRILLION dollars, batteries NOT included! ...and you WOULD need batteries - LOTS of batteries! Batteries (for night time and cloudy days), controllers, and tracking apparatus (to keep the panels pointed at the sun - shown right) will probably cost another $30 trillion...(There may be an answer to the battery problem - see smart grid.)

Don't forget - the sun doesn't shine at full power 24/7. Don't forget -in the real world- solar collectors only deliver their rated power about 16% of the time; and as shown by the insolation map below, there is huge variation in different parts of the world.