Dispelling the Myths of Solar Electricity: Energy Payback

| 3/26/2010 2:20:00 PM

Tags: Dan Chiras, PV systems, solar energy,

 PV systems 

You may have heard it said that it takes more energy to make a PV system than you get out of it over its lifetime. Fortunately, that’s not even close to being accurate.

While it takes energy to make solar cells, modules and the rest of the components of a PV system, the energy payback is actually amazingly short — only 1 to 2 years. Research conducted by CrystalClear, a private company, has shown that it takes two years for a PV system with monocrystalline solar cells to make as much energy as was required to manufacture the entire PV system. Researchers also calculated the energy payback for polycrystalline cells and polycrystalline solar cells manufactured by the ribbon technique. The calculations estimated that it took 1.7 years for a polycrystalline system to reach this point and 1.5 years for modules made from ribbon polycrystalline PVs. A previous study showed that thin film modules, which require even less energy to produce, achieved energy payback in one year.

These studies were performed for sunlight conditions similar to those found in southern Europe with an average insolation of 4.7 peak sun-hours. For those who live in sunnier climates, the energy payback will be even quicker. For those who live in less sunny regions, the payback would be slower.

As it turns out, most of the energy required to make a PV system is used to produce modules — about 93 percent of the entire energy budget is devoted to making modules. As just noted, the most energy-intensive modules are those made from monocrystalline solar cells. Polycrystalline cell modules require 15 percent less energy to manufacture than monocrystalline modules. Ribbon cell module production is even more efficient. It requires 25 percent less energy than monocrystalline and about 12 percent less than polycrystalline to make a ribbon cell module. Thin film uses even less energy, about 50 percent.

“Given that a PV system will continue to produce electricity for 30 years or more, a PV system's lifetime production will far exceed the energy it took to produce it,” writes Justine Sanchez in her 2008 article in Home Power entitled “PV Energy Payback.”

tim sefton
11/17/2011 3:20:53 PM

Solar is great but you need some type of energy source for when the sun is not shining - we're in Michigan where it can be cloudy for days - We working on a project developing and building a low cost stirling engine for electrical generation that would work well for when its cloudy - We are targeting a building cost of $110 for a 1KW output - http://www.kickstarter.com/projects/672465444/low-cost-sterling-engine

5/12/2011 11:37:25 AM

Oil which oozes out of the ground is always going to be cheaper than anything else plus oil is subsidized. There are environmental costs with fossil fuels. So I am not really interested in hearing complaints about subsidies for solar. http://www.washingtonpost.com/politics/senate-democrats-push-to-end-tax-breaks-for-big-oil-companies-to-cut-deficit/2011/05/10/AFiL42hG_story.html

ron laurie_1
4/3/2010 7:17:18 PM

to Tom Stechschulte In 1991 Texas Instruments developed a solar system and backup "battery system" that was tested in Ottawa Canada for a full year. On anouncement of the results thier stock jumped 25%. Ontario Hydro ( a provincially owned utility) bought up the patents immediately. This system had cost $15,000 to retrofit the house. It provided all the electrical needs of this home in northern Canada in this city dwelling. The low cost of a new technology in silicon cell manufacture also kept the cost low. The real key was the power storage system. The storage system was capable of returning 80% of the power fed into it. Any excess was fed back to the grid and payed for at wholesale rates. Check it out.

4/3/2010 4:30:24 PM

blainenay If solar and wind energy, --- why do these technologies need substantial government subsidies (at taxpayer expense) to be viable? I If their advocates are to continue to tout the benefits of these technologies, they must first demand Congress remove all subsidies. Let these technologies succeed or fail purely on their merits. Anything less is pure hypocrisy. HYPOCRISY!?!?! blainenay You have no clue the HUGE GOVERNMENT SUBSIDIES the oil industry is sucking out of the American budget, not to mention the Iraq war! And they destroy the environment!

roy fritz
4/3/2010 11:41:31 AM

If you wish to find some helpful information I would suggest going to "otherpower.com " they have alot of good information and good people. Anything from wind to solar to hydro can be asked and good people will answer. Just an idea to help people life off grid.

roy fritz
4/3/2010 11:21:13 AM

There is a $$ balance that needs to be addressed that must be the meeting piont of power used and power needed and power available. If building a solar power only there is alot of homework needed even with a backup generator. Alot of people get a good idea but fall short when they fail to orgainize their power uasage. Using power wisely helps most people balance their systems. Alot of normal items such as TV's use power even when not being turned on the same as oven computors. A disconnect power power switch on such items should be looked into. Solar and wind and micro hydro systems are great sources of energy but living the off grid way of life means you need to change the way you use electicity. Just me two cents worth. Off grid in 651 days and counting.

4/2/2010 7:26:41 PM

Mr. Stechschulte, keep you Eye on company call EEStor: EEStor Inc., a privately held company based in Cedar Park, Texas, was founded in 2001 by Richard Weir and Carl Nelson, former senior managers in disk storage design and manufacturing at IBM and Xerox.  EEStor has patented an Ultracapacitor storage device, an EESU (Electrical Energy Storage Unit), that acts like a super battery but with characteristics that overcome all of the challenges inherent with lead acid, lithium or nickel-metal hydride batteries. They are partnered with a company called ZENN. http://www.zenncars.com/ The storage units are being developed for use in Electric Vehicles, but I don't see why they can't be used in homes as well.

4/2/2010 7:14:41 PM

I agree with the post about removeing all subsidies. If that were to happpen then the oil and gas inddustry would not seem as attractive as it does now. Levelling the playing field works for all technologies, Big Oil just seem to be able to cover their subsidies a lot better.

erica etelson_1
4/2/2010 3:51:52 PM

Another myth about solar is that the up-front installation cost is so high that it takes 20 years before you break even. That's rapidly changing with the invent of the "solar lease" or "power purchase agreement" from installers like Sungevity.com and others. I'm leasing a grid-tied PV system for zero-down and paying what I used to pay for electricity. Very cool.

tom stechschulte
4/2/2010 12:49:32 PM

I currently am off the grid. I have a ten panel solar system of 165 watts each. I live in SW Utah at 7800 ft elevation. We have a propane back-up generator. My battery system is a 1200AH gel battery system. I have been living here since December 2006. My trouble does not seem to be with the amount of electricity generated but with the storage of the power. It is very difficult to find objective information about battery systems. In my opinion that is the weak link in PV solar systems. The batteries (storage capabilities) have not kept up with power generation capabilities. I must run my generator for 2 to 3 hours every night except in late May to late August. Any advice out there?? Thanks, Tom Stechschulte

4/2/2010 10:55:46 AM

I don't know where that "under 1000" figure is from. Where I'm at a grid tie in costs more then that. Arkansas has no incentives to install solar and to top it off the cost of powering your house is cost prohibitive. Net metering here is set so you are paid nothing and if you produce extra power you're giving it to the power company. Say I normally use $150 bucks worth of power a month and I produce $200 bucks through solar giving me a $50 credit. At the end of the 12 month calendar period the power company zero's out the account not paying the balance owed you. Until the cost goes way down this is like the other aternative power sources, nice to know it's there but it costs too much and will not be adopted.

4/2/2010 9:47:41 AM

How did you arrive at the $1000 cost. Around here a 200 watt solar panel cost about $1000 ( on sale at $850 on rare occasion) and that doesn't even include the wires needed to connect the PV panel to any batteries. At that price I assume the batteries or grid tie equipment is free. And a 200 watt solar panel will not provide anywhere near enough power up here at latitude 54 especially during a 16 hour long dark winter period with maybe 2- 3 hours usable sunlight. That is assuming no cloud cover and the 24" snow fall gets cleared from the solar panel immediately, and before the sun rises.

4/2/2010 8:52:11 AM

If solar and wind energy, battery-powered and hybrid cars, and alternative fuels such as ethanol and bio-diesel are such good deals, why do these technologies need substantial government subsidies (at taxpayer expense) to be viable? If their advocates are to continue to tout the benefits of these technologies, they must first demand Congress remove all subsidies. Let these technologies succeed or fail purely on their merits. Anything less is pure hypocrisy.

renewable ray
3/29/2010 6:16:51 PM

We all are victims of propaganda from the "professional installers" of the world. I will scream if I have to read "it takes $20,000 to install solar on your home. With today's reasonably priced GTI's [grid tie inverters] a do it yourselfer cab be selling power to the grid for well under $1,000. Ray @ New World Solar http://newworldsolarpower.com

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