How come solar panels are not very efficient?

Question

I need to write a paper on alternative energy sources for school.

Answer 1

Solar panels use a lot of different materials, but silicon is the most common. The problem is that slight imperfections and impurities in the solar panel dramatically decrease the amount of electricity that can be produced.

Answer 2

Often the panels themselves are not the problem. To get useable solar energy out of a PV panel, you need to go through several sources, all of which have efficiencies of their own .

You get energy from the sun, which is collected by the solar panel. Some of the light bounces off of the panel, some will pass through and turn into heat behind the panel. Only a certain percentage of the energy is trapped by the PV panel. After trapping the energy, the panels produce DC current (this kind is not used in most buildings). The current is stored in battery banks, which lose some energy as well. The energy can only be stored so long in the batteries, so they are not 100% efficient. Finally, the energy will leave the battery bank and go through an inverter to transform the DC current to AC current (the kind that comes out of the plug in your home.) The inverter is also not 100% efficient, though it can retain as much as 96% of its energy with no problem.

(Btw. PV = photovoltaic)

Mostly, solar sources are not effective because many places do not have enough sun throughout the year to power a building.

Other good alternative energy sources: solar thermal (evacuated tubes - they produce hot water from sitting in the sun), wind power (again, only in certain areas), geothermal (like old Faithful at Yellowstone - use that kind of power), hydropower (only if you have a big enough river), and biomass (this is corn, waste products, wood, methanol produced from garbage dumps).

Answer 3

The above answer seems to take care of your paper for school. I just wanted to point out that a car or truck is not as efficient as solar. The engine produces a lot more power then is required to drive you down the bock to the store to buy a Coke. Yet people still buy bigger motors and faster cars and pay 10 to 20 times the value of the car just to look cool. I guess you can't drive a solar panel to the night club and look cool like you can in a corvette which has zero return on your investment. You can't even plug your corvette into your house to run your freezer when the power goes out.

So is solar panels efficient or not? Just depends on what you are comparing them to.

Answer 4

With solar panels, the only thing you gain from a more efficient panel is the ability to produce more electricity from the same amount of area. If you have lots of area for a solar panel, then it's much cheaper to use more panels that are less efficient than to use fewer panels that can me much more expensive. An efficient panel can cost ten times or more than a less efficient model.

Efficiency is the power output divided by the light power incident on the panel.

Answer 5

because there's no such thing as a free lunch.