how long would a solar cell have to work to re-coup the energy used to make it?

Answer 1

I'm taking a class at UCLA about climate change and we had a speaker that made and installed solar cells. He said there were different types, some more efficient, but some more appropriate and style friendly. He said that they last on average about 30-40 years. As you know their manufacture is extremely energy intensive, and he said that they took about 4-7 years (depending on model) to save the energy that were used to make them. In the end though you have to take into accout that these solar cells could be made by other renewable energy sources at least in part, so this figure might be a little less, and their usage is still very important.

Answer 2

Well, I see there are many answers, I thought the answer is that in less than 5 years, savings in your electric bill would cover the price of the solar cells.
In California, you can sell the extra power you make, say, at noon time, when production is high and use low, to the power company, at the time when they reach the peak commercial power use -and the price of electricity is the highest.
Also, a new kind of solar power cell has been developed that produces 50 percent more power and is cheaper; it will reach the markets by the end of this year. This was done by using a more efficient chip.
Another approach is to focus sunlight with mirrors which puts more energy on the cell and produces more electricity. This alone, also increases the power by about 50 percent.

Since the sun energy is free, in principle, one could use the electricity to produce Hydrogen from purified water. The Hydrogen can be used to power a home, bike, car or bus.

Don't pay attention to those that say "gasoline is cheaper than Hydrogen". They probably do not know gasoline prices.

Answer 3

This depends on the type of solar cell, but they will recoup their energy sometime around halfway through their life cycle. From Wikipedia:

"The energy payback time of a solar panel, assuming a working lifetime of around 40 years, is anywhere from 1 to 20 years (usually under five)[2] depending on the type and where it is used (see net energy gain). This means solar cells can be net energy producers meaning they generate more energy over their lifetime than the energy expended in producing them."

Answer 4

there are MANY MYTHS on this....
Generally the average rule is about 10 years to pay itself back financially if placed well.
It depends also what type has been made and how much precious materials have been needed to make (ie. silicon)
You also need to consider if I was to place a solar panel to light a house in the desert this cannot be comparable to how much energy and costs it would take connect that house up to the grid.
This is why is a lot less energy intesive to run Remote area systems eg. payphones and street lights from solar panels as it would be stupid to try to connect them up to mains electricity. In this scenario they would re-coup a lot more energy than a mains grid setup.
It really depends on what type of panel it is, how it is made, how it is placed, what application it is providing.
However most Solar Hot water systems take 1 year to pay back their energy costs, and 3-4 years to pay back their financial cost.
It is just the main expense of silicon in electricity gen. from the sun.

Answer 5

The real issue has nothing to do with the amount of money or energy used to make the solar cells. The issue is what is the life of the installed cell and the net net energy savings over time.

Even if it requires 10 to 50 years to get back the energy used in the manufacture of the cell (and these are very pessimistic numbers), if the life of the cell (which has no moving parts) is measured in centuries then the investment is well worth it.

Answer 6

If you assume the cost to make it is a measure of the energy used to make it, which is not 100% true but it should be close enough, then it is somewhere between 11 and 54 years given the amount of sunlight at my location. I live in a pretty sunny location (Austin, Texas), but there are places in Arizona that get more sun, so payback would be faster there. But there are plenty of places that get much less sun, like Seattle, where payback would be much longer.

According to the 1st source, a $925 solar panel will make 180 watts in full Sun. Given average conditions at my home location, again using information from the 1st source, I calculate it can be expected to make about 196 kilowatt hours per year, what with clouds and sun angles and so on. My electric company charges me $0.0867 per kilowatt hour, so the 196 kwh per year the solar panel makes is worth $17. Dividing that cost into the price of the solar panel says it will take over 54 years to pay for itself.

Another way to look at it is by energy intensity of the economy. The 2nd source says it takes 9 MJ for the US economy to make one dollar. 9MJ is 2.5 kwh. So if the energy intensity of the solar panel manufacturing process is equal the the US average, then it took 2.5 * 925 = 2312.5 kwh to make the panel. It makes 196 kwh per year, at average conditions in my location, so that means it takes 11.8 years to make as much energy as it took to produce.

Answer 7

Most manufacturers estimate the re-coup time to be about two or three years, but that obviously depends on where they end up being used. The main factors that will determine the payback include a south facing orientation, the shading that they experience throughout the year, the angle of the orientation of the module, the local weather, etc.

Answer 8

It depends on how much it costs.
Take how much the solar cell produces in a year. (average)
Subtract the cost the electric company will cost for that same electricity.
If the cost of the electricity is 300 bucks, and the cell cost's 3,000. It would take 10 years to recoup the money. If the cell lasts 20 years, you save 3,000 dollars.
Its up to you to decide how long you will live there, and if 3,000 in savings after 20 years is worth it.

Answer 9

solar cells are just an secondary source of storeing energy

Answer 10

It depends on how large it is... the larger the more time I'm sure.