What could be the energy efficient products powered by solar energy?

Answer 1

Answer
It isn't. Just because it harnesses energy from the sun, i.e., a natural source, does not make it efficient. To understand efficiency, one must understand the relationship between economics and efficiency. That which is economically efficient is efficient.
Thus the issue is not where the energy comes from, but how much energy is produced through solar technology, and how much energy is consumed (i.e., what is spent) in harnessing energy from the sun.
In order to harness energy from the sun, solar panels must be built. This requires labor and time, as well as mining for Natural Resources such as copper, etc. Throughout all of these activities, energy is consumed. In fact, EVERYBODY CONSUMES SOME FORM OF ENERGY IN EVERYTHING THEY DO. In order for A to spend energy doing X, B must spend energy producing, for example, food in order for A to sustain himself.
One needs inverters and charge controllers in order for solar systems to work. Batteries must be produced, used, and replaced as well, which is a huge drain on resources, i.e., energy. Thus the energy produced vs. energy consumed in solar power makes it inefficient.
One of the most efficient, and thus inexpensive, forms of energy comes from coal. Barack Obama has already stated his desire to destroy what remains of the coal industry in the United States. When that happens, common people will find turning light bulbs on to be a form of luxury.

CommentUnfortunately, too many discussions on this topic confuse several very different forms of energy efficiency to reach an incorrect conclusion:
* conversion efficiency: Given some "raw" natural resource containing some theoretical amount of energy R Joules (light from the sun, coal deep in the earth, etc.), when I convert that resource into E Joules of electricity, what is the efficiency E/R ? This efficiency is always less than 100% for every energy source. This number is easy to measure, but irrelevant on its own.
* extraction efficiency: Given some "raw" natural resources, I have to put in a certain amount of energy S Joules (roughly equivalent to start-up costs: the energy to run the tools to dig into the earth and pull coal out of the earth and carry the coal to the coal-powered electric generator; the "embodied" energy required to build solar panels; etc.), after which I get E Joules of electricity out. This ratio E/S had better be more than 100%, otherwise you're better off doing "nothing" and converting those S Joules into electricity directly. Typically an oil well flows freely when it is first drilled (it takes very little energy S to run the pump in order to get lots of energy E out), but it gets more and more difficult to pull the next barrel of oil out of the ground. In theory, you might reach the point where it would take more gallons of oil to run the pump all day than it produces that day -- a smart operator will shut down that well before that happens. Some of the very first solar cells produced had a E/S ratio less than 1, but today's solar cells (over their lifetime) produce 6 to 10 times the amount of energy required to produce that solar cell. See the "Net Energy Analysis" link below.
* Economic efficiency: some ways of producing electricity require constant attention by lots of high-paid people; other ways are more-or-less automatic once set up. Some ways of producing electricity require mind-boggling amounts of start-up costs; others can get started on much less. Some locations have a government that requires certain ways of electricity production to pay high insurance and security costs, other ways have lower costs, and some ways may be subsidized. Sometimes there is a method of producing electricity that is perfectly reasonable, when considered by itself, and there are more than enough people who would be willing to fund and build it, when considered by itself; but it doesn't get built because those people found some other way of producing electricity that generates more electricity at lower cost.
* Sustainable efficiency: There is a finite (although very, very large) amount of matter and energy available to us. There are some ways we can "use" matter and energy in ways that our children, grandchildren, etc. can continue to do the same for thousands of years. There are other ways we can "use" matter and energy in ways that "use it up", forcing our children, grandchildren, etc. to find some other way to get the energy they need to survive.




However, after the solar panels are put in place, they do less damage to the Earth. They are dependent on a renewable source: the Sun. Coal, fossil fuels, eco fuels etc. all come from Earth, and coal and fuels cannot be replenished. The Sun is a constant, renewable source. Solar energy would be efficient in reducing carbon emissions and stopping greenhouse gases, as solar energy is directly changed to electrical energy. Coal and fuels must undergo chemical processes, and form carbon dioxide and other gas emissions which are harmful to the atmosphere, increasing greenhouse gases.

Answer 2

Well lights in the house, garden lights and your water heater can all be powered by solar energy.

You can also have a battery that is charged by solar energy and other appliance can then be connected to this battery.