How much CO2 does one solar panel create?
Yes, it's true that making solar panels creates carbon dioxide, but over the life of a solar installation it produces on average of 30x less CO2 than coal power.
Sat, Jul 17 2010 at 4:32 PM EST
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Photo: EnviroThink Whenever I sing the praises of solar PV as a means to hugely reduce U.S. carbon emissions while strengthening the security of the grid, I get people complaining that I'm not disclosing the carbon impacts of solar panel production.
So let's get this straight.. solar panels are at least 20x better on the climate than coal, kWh for kWh. I say at least because the most often cited report is by Danish utility Vattenfall from 1999. It looks at only 3 countries -- Japan, Sweden and Finland -- all of which are fairly dark and dreary, and it does not account for recent advances in PV production (new solar panels are significantly more efficient).
Based on that study, solar PV works out to about 50g of CO2 per kWh compared to coal's 975g of CO2 per kWh, or about 20x "cleaner."
Coal power plants in the U.S. are considerably less regulated (and therefore less efficient) than their European counterparts, making them more carbon-intensive. And the U.S. has much greater solar access than Japan or Sweden, making solar PV less carbon-intensive.
Here's a comparison of several scientific studies on the carbon life-cycle costs of solar (both PV and thin film). The gist is an average 3 year payback... meaning after 3 years the solar panels create as much energy as was consumed in their initial production and installation. In the remaining 22-27 years of their life span they would be "carbon negative."
Now depending on where you live, this payback period could vary significantly. Here's a chart of "peak sun hours" in the U.S. (a numerical equivalent for the amount of time that the sun averages 1 kWh per m2 of intensity):
Say you bought a standard 224 watt solar panel and stuck it on your roof in an optimal location with no shadows. The panel is rated to produce 224 watts of power in 1 hour of peak solar intensity. So if you live in Santa Fe, New Mexico you would generate 6 x 224 watts = 1.33 kWh in one day with that one panel. You have to shave off about 10% for efficiency losses (inverter and wiring) so in Santa Fe you're looking at 1.2 kWh of production per panel per day, or 438 kWh's per year.
In Cooperstown, New York you have roughly half the solar intensity, approximately 3 hours per day of peak, so there you would expect to produce 0.6 kWh with the same panel each day, or 219 kWh's per year. The national average is somewhere in the middle (about 4.5 hours per day) so on average in the U.S. a 224 watt panel creates 0.9 kWh per day or 328 kWh's per year. Over a typical 25 year lifespan that panel would produce about 8,200 kWh's.
Stockholm, Sweden where the Vattenfall study was performed, gets 3 peak sun hours just like Upstate New York, producing about 5,500 kWh's over its typical 25 year life span. According to the study, a solar panel in Sweden generates 50g of CO2 per kWh so that is a total of 274 kg of CO2, or 600 lbs of CO2.
Though there are some efficiency losses for solar panels in hotter climates, ostensibly the same 600 lbs of CO2 could get you twice the amount of energy in Santa Fe, New Mexico making it 40x less carbon-intensive than coal power and the national average would be about 30x less carbon intensity for domestic solar PV.
If you want to get really exact efficiencies for your area check out the awesome PVwatts calculator.
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Comments
loganrides
09/27/2011 21:55 PM
I got several bids over the past few weeks from a few San Francisco roofing contractors to install these solar panels on our roof. The cost really isn't as bad as I thought, but our overall savings is supposed to cut down on our utilities by 40%. Plus, my understanding from the roofers is that we will get a tax break for putting this in. The guys start next week, I'll keep you.... More
Kyle
06/28/2011 13:41 PM
My wife and I have been looking into adding these solar panels to our home and try to turn our house into a greenier house. My wife has been investigating, what and where to buy and have discovered that you may need to protect your home with a different type of siding in order to get the full benefit of solar energy. Is this true or just a gimmick to sell siding?
Anonymous
06/28/2011 13:53 PM
The only benefit of adding special siding would be to improve the energy efficiency of your home as a whole. If you are losing heat through your walls then of course improving your insulation and siding will help.
But from the perspective of whether siding upgrades are required to maximize your solar panels...no.
John Daniel
03/27/2011 09:29 AM
Has anyone looked into the kits or guides that show you how to make solar panels? Very intrigued and curious if these things work. My neighbor turned me on to this site: Solar Panels Make Easy DIY Project Let me know if you have tried this out or not. thanks
John Daniel
03/27/2011 09:32 AM
whoops, not sure that website came through on the DIY solar panel kits. Here it is again: http://www.solarpanelsmake.com
thanks
DavidCognito
07/25/2010 17:55 PM
Karl,
The graph you've used for g CO2 / kWh is not credible. It's from a nuclear operator. The Sovacool meta analysis is a more reliable benchmark:
Lifecycle CO2 emissions g / kWh: wind = 10, hydroelectricity = 13, solar thermal = 13, solar photovoltaic = 32, biomass = 14 - 41, nuclear = 66, natural gas = 443, coal = 1050.
samuel
07/22/2010 13:35 PM
what is the price of a solar panel
ns
07/19/2010 22:57 PM
there needs to be a comparison made on the CO2 emissions from coal mining vs panel manufacturing?
jef
07/19/2010 19:30 PM
How much total CO2 will solar panel reduce in its lifespan?
John
07/19/2010 09:17 AM
What about the batteries used to store the electricity? They wear out before the 22-27 years sited in the article.
tempo36
02/23/2011 18:13 PM
The vast majority of installed PV systems in cities are installed as grid tie-in. This means there are no batteries. Instead of storing power when you are making more than you consume, you feed it back into the grid and your electric meter turns backwards. Many utilities now credit your bill for this. This solves the need for batteries to store excess generated power.
The down side is that grid tie-in systems are designed to shut off if the grid loses power. So during a black-out you.... More
P Ness
07/19/2010 07:09 AM
and no one ever caculates the impact of disposal after.
what is the impact of that?
anon
07/19/2010 03:24 AM
@s
apparently sweden is different... last i recall, it only takes one post to make a point, and posting more than that just makes you spam... welcome to the food chain
@Mark_e_Evans
07/19/2010 02:25 AM
With a headline like this, I expected a conversation about the carbon/environmental intensity of solar panel manufacturing. That's an interesting, and largely unaddressed issue.
You're talking about the net energy production difference per carbon produced, independent of manufacturing. I don't think anyone credible is arguing that solar panels (1) generate power, and (2) generate power with less carbon intensity per unit than coal.
S
07/19/2010 00:57 AM
#1. They consume less energy than Americans.
#2. The only reason why 43% of the Swedish primary energy supply comes from renewable sources (which is the largest share in any European Union country) is because of a GOVERNMENT MANDATE. And everyone in America hates government mandates.
So it would never work in America. I hope these Americans just keep consuming until they all drop dead from asthma, heart disease, and diabetes.
Tim
01/13/2012 19:44 PM
The main reason why the US doesn't have more renewable energy and electric cars is not totally the fault of US citizens. They do take a good deal of blame for not wanting to change their way of life and realize the savings of doing so, but the main barricade is that the fossil fuel industry owns our government. Most of our environmental regulations are being reversed by the Republicans that have been bought by these companies to "cut spending"in the budget, but they won't touch the billions of.... More
