I’ve seen several discussions on blogs regarding the net engergy gain (or loss) of solar systems. Some people claim it’s a net energy loss, but I have a hard time believing that to be true. Can anyone answer with either a credible source or facts that back up their answer? I’ve done a lot of searching and found very little to help me clear up this question. And please don’t mix financial information into this discussion, I’m only interested in the net ENERGY of solar electric (photovoltaic) systems.
More Pages:
- Solar Panel: What Kind Of Solar Panel Do I Need To Power A 130W Electric Motor? (8/6/2011)
- Solar Energy For Home – Does My Solar Electric System Have To Include Batteries?
- Solar Turbines: What Is One Advantage Of Using Wind Turbines Rather Than Burning Fossil Fuels To Produce Electricity? (7/22/2011)
- Solar Energy: How Much Do Solar Energy Panels Cost? (5/15/2011)
- Solar Energy: What Type Of Electricity Can Produce From Solar Energy: Ac,dc Or Both? (6/23/2011)
{ 5 comments… read them below or add one }
It is not simple to answer.
there are several different technologies
and many differnent working environments and load factors.
high-spec NASA pannels, clean room semiconductors, redundancy & destructive testing. and a short hostile life generating little useable power – perhaps the case could be made the are a net energy loss.
organic (dye) photovoltaics, although having lower efficiencies, are much simpler to mass produce, so less net energy input
and in normal use should give ample life to give a positive energy gain. unfortunaly still very much at development stage so no easy to read summaries
No, the energy used to manufacture a PV system is not greater than the energy produced by a PV system in its lifetime. To calculate the net energy of a PV system, more information is needed (like the size, location, manufacturer).
Good luck in your search.
The answer depends on a number of variables. Some of the more important variables are:
1.Whether the system is installed as fixed posotion or able to follow the path of the sun during the day. A system that can follow the path of the sun will produce much more electricity. This is why roofing shingle solar panels do not work well and panels that lie flat on the roof do not work well. The panels need to be up in the air at right angles to the sun and follow the path of the sun throughout the day to have optimum output.
2. The latitude where the system is installed. At higher latitudes the system will produce less electricity.
3. The average cloud cover where the system is installed. For example a system installed in a location with a great deal of fog or cloud cover, such as San Francisco, California will produce less electricity compared with a system installed at the same latitude but with less cloud cover, such as Fairfield, California.
4. How well the panels are cleaned and maintained. Solar panels get dirty like the windows in your house and their electricity output drops considerable when they are dirty because the sunlight cannot get through. The panels are often in a location that makes them difficult to clean so the panels are often not well maintained and kept clean and electrical output often drops considerably.
In general a well maintained system that is designed to follow the sun, installed at a latitude of 45 degrees will produce as much energy as it took to make the components in about 7 to 10 years. Assuming the expected life of the system is 25 years, it will start producing a net positive energy contribution after 7 to 10 years, and for the remaining 15 to 18 years of its useful life.
I hope this helps.
Pretty simple… follow the money.
If a solar panel didn’t over its life provide more energy than it took to produce the panel… the panel would never “pay off” by the amount of energy you no longer have to buy from the electric company.
Since panels PLUS BATTERIES PLUS REGULATOR can pay off in 4 to 6 years… it becomes obvious that it CAN’T use more energy to make the panel than what the panel produces over its useful life.
I have looked into this issue as well, and finding data does take some serious searching. Part of the problem is that it is very hard to fully calculate the energy inputs required to create a system, let alone to correctly average these costs across the many types of PV systems available.
In speaking to solar installation experts, what I understand is that today’s solar panels are lasting a tremendously long time. As with hybrid car batteries, there is a set period of years covered by warranty and a period of years that the cells are expected to still gather a large (90% or so) amount of their stated power. But, the reality is that installers are seeing the systems work at 95% efficiency multiple decades after installation.
This makes the calculation even harder (we don’t know when the system will actually stop saving energy), but has helped me to believe that the PV systems will save a significant amount of energy over their usable lifetime. This will only improve over time as the new systems we keep reading about come to market.
In searching for answers I found some research I have linked to this answer. Basically
- Australian study concludes a system lasts 30 years, takes the first 8-11 to pay back the energy (60% of which is from the wafer manufacture). However, they note that systems may last 40-50 years! They further project that a system created in 2010 will likely require only 2 years to pay back, due to the increasingly efficient technology.
- June 2006 article on a study that averages several studies to conclude a payback time of 4 years.
- National Renewable Energy Laboratory study concluded a 4 year pay back.
The above articles also make it clear that there is a very favorable net pollution reduction as well. PV seems to be a great way to go!
I don’t want to stray off topic too much, but you may also wish to look into solar water heaters, which are often simpler (likely lower energy input) and generate the same energy reduction for a home (but at a lower $ cost).