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Another PV ERoEI debacle May 17, 2016

Posted by Maury Markowitz in balonium, solar.
Tags: ,

Your face should have this expression when you read Ferroni and Hopkirk’s paper.

recent report by Ferroni and Hopkirk explores the energy balance of solar power, and concludes that using PV is energy negative. That is, building PV requires more energy than the panel will produce over its lifetime.

Claims like these pop up from time to time, and normally end up being based on definitional tricks on the part of the authors. This example is no different in that respect, but in this case they also add a liberal dose of bad data.

The paper is so filled with errors and omissions that’s it’s almost breathtaking. Once again, dear reader, it’s time for the deep dive.

The sincerest flattery

While googling myself (I can’t remember my URL any more than you can) I found to my delight that the name of this blog has been taken up by a pair of bloggers from Aberdeen. A May 9 post by one of the authors pointed me to the paper that is the topic of the rest of this article.

After stating that the topic of ERoEI is new to the blog, he goes on to note that when he came across this paper, “the findings are so stunning that I felt compelled to write this post immediately.”

When I come across a study in the renewables field with findings that are “stunning”, I normally hold it at arm’s length until I can run the numbers myself. That’s because the field is utterly filled with bogus information from thinly disguised coal company shills to the nuclear true believers. Don’t get me wrong, there’s just as much BS going the other way, from the usual suspects to the space heads, which is all the more reason to be super-skeptical.

While Mr. Mearns does make some comments about the validity of certain inputs in theoretical terms, in the end, he quotes the bottom line:

Solar panels will produce only 0.83 times the amount of energy they take to produce… If correct, that means more energy is used to make the PV panels than will ever be recovered from them during their 25 year lifetime.

That’s a big “if”, isn’t it.

And guess what, it’s not correct.

Start bad…

So let’s get into the meat of it. The paper starts with the authors having examined 28 other papers on the topic and found they had a wide variability of Cumulative Energy Demand (CED), the amount of energy used by a product over its lifetime. They conclude that “the authors … were not following the same criteria in determining the boundaries of the PV system.”

Now getting the CED is important, because the overall energy balance, ERoEI, is basically energy out divided by energy in. So you’re going to need to have a good value for that CED, and they’re all over the map. Then, after complaining about this, their solution is to define an entirely new version – yay!

But now they change gears and work on the other side of the equation, the total energy produced. And they attempt to do this in per-square-meter terms.

Now stop right there.

The industry, and I mean the entire power industry here, not just the renewables industry, measures everything in either per-watt or per-kilowatt-hour terms. That’s because the physical mechanisms of the generators differ wildly, but a watt(hour) is a watt(hour), so when you convert to those terms you have a real apples-to-apples comparison.

Consider an example; if I tell you a hydro dam cost $2/Watt and a new wind turbine costs $1.50/W, well, there you have it. Now, what if I told you that the dam cost $2 per square meter and the turbine $10? That sounds like the exact opposite. And then, does that area include the reservoir? Does the turbine include all the area around it or just the actual footprint on the ground?

See the problem? The area is tough to pin down. Dollars are not.

So why would the authors pick such an odd unit? I can’t say for sure, but in the abstract, they mention something about how “solar radiation exhibits a rather low power density”. Well, sure, and that’s important why? Apparently, it’s not, because it only figures in very peripherally in the calculations, and has no effect on the bottom line.

Well let’s get to the numbers at hand:

The data are available in the Swiss annual energy statistics … and show an average value of 400 kW ht/m2 yr (suffix “t” means “thermal”) for the last 10 years. This is an indication of the rather low effective level of the insolation in Switzerland. … The uptake from the incoming solar radiation is converted into electrical energy by the photovoltaic effect. The conversion process is subject to the Shockley-Queisser Limit, which indicates for the silicon technology a maximum theoretical energy conversion ef- ficiency of 31%. Since the maximum measured efficiency under standard test conditions (vertical irradiation and temperature below 25 °C) is lower, at approximately 20%, the yearly energy return derived by this first method in the form of electricity gen- erated, amounts to only 80 kW he/m2 yr.

Ok, if you don’t really know much about solar power, you might not immediately see the problem with this statement. What they’re doing is a double conversion – they’re not calculating the amount of energy produced by a PV panel, they’re taking the amount of heat collected by a thermal panel, then applying a formula to convert that to expected electrical power production.

I-See-What-You-Did-There-Fry1But that conversion is totally wrong. The Shockley-Queisser Limit doesn’t work on thermal energy, it works on the original solar energy. And no, the thermal energy is not a good proxy for the original solar energy. The main contribution to the losses in PV, the SQ limit, is wavelength, which doesn’t come into play in thermal collectors. And the main contributor to losses in thermal collectors is ambient temperature, which has a minor effect on PV.

The two are just not the same, you can’t do that.

But more to the point, why would they do that? Because the same source they quote for the thermal value publishes actual electrical output figures as well, which they then go on to quote:

According to the official Swiss energy statistics (Swiss Federal Office of Energy, 2015), an average for the last 10 years of 106 kWhe/m2 yr is obtained for relatively new modules.

This number is 30% higher than their calculation based on thermal, a discrepancy they don’t even try to explain.

Beyond that, any number that is “an average for the last 10 years” is, by definition, not talking about “relatively new modules”. Ten years ago the average panel was about 160 Watts and cost about $5.00/Wp. Today they’re around 280 Watts and cost about $0.45/Wp. The vast majority of the world’s PV was installed in the last three years, so any calculation based on data older than that is just plain wrong.

SolarGIS-Solar-map-Europe-enAnd even this number, 106, is significantly lower than I would expect given that Switzerland has fairly average insolation for mid-latitude Europe. So what’s up with that?

Well, when I checked the cited source I found that no such number is actually reported. One can only find total output numbers and then work back from there, but the authors fail to give their calculation. And those totals  -wait for it- go back over a decade, so we’re right back to that problem again.

Which is all the funnier when you consider that such data is trivially available on the ‘net. Anyone who wants do to do this calculation should do what we all do; use NREL’s PVWatts. It has highly accurate weather data going back 30 years taken only from first-class sensors.

I typed in Zurich for the location and selected the TMY3 data set. For the system size, I considered a typical modern 280 Watt panel at 1.6 m², or 175 W/m², and typed 0.175 into the System Size. I also changed the tilt from 20, which is good for California, to 30, which is good for Zurich. And here it is:

Screen Shot 2016-05-16 at 10.05.02 AM.png

They said 106. We’re at the very first number in the paper, and they’re already off by a factor of 60% from what the industry standard tool suggests.No attempt is made to explain this, except for dismissive comments about industry calculators.

 …get worse…

Now the authors turn their attention to the expected lifetime of the panels, which is needed in order to calculate the overall lifetime energy production. They do so in a rather convoluted fashion, starting by considering the weight of panels recycled in Germany:

This was 7637 t. A module of 1 m2 weighs 16 kg and 1 kWp peak rating needs 9 m2 and consequently, scaling this up, a 1 MWp module will weigh approximately 144 t.

Hmmm. A SolarWorld 280, a typical modern panel, masses 17.9 kg. That’s 17.9/1.6 = 11.2 kg/m². I really have no idea where they got their value, and they don’t include any reference. A 1 MWp system using these panels would require 1 million / 280 ~= 3570 panels, or 3570 x 17.9 = 63,903 kg = 64 t. So now we’re at calculation number two, and we find they’re off by another factor of two.

The paper goes on to use these numbers to suggest a typical lifetime is about 17 years. Now the problem is that if older panels are heavier, then the number on a per-kg basis is automatically skewed towards older panels again. Or to put it another way, if you had 10 panels from each year since 1990 and scrapped one from each year, when measured by weight it would seem that more older panels are dying.

And once again I’m left scratching my head why they would use this convoluted logic when one can find real values in seconds. In fact, one of the most quoted examples is right down the road from them on the LEEE-TISO buildings. The vast majority of these panels, apparently the first grid-tie system in the world, are still running fine after almost 35 years. They calculate the losses at 0.2 to 0.5% a year, which corresponds to a panel lifetime on the order of 60 years.

…a little more…

They then ignore their previous calculations and use a 25 year lifetime. So apparently all of that was for nothing! And that brings us to this:

Experience has shown that, on average, efficiency and hence performance de- gradations of around 1% per year of operation must be expected (Jordan and Kurtz, 2012).

Now we go from bad to terrible. They claim this 1% number comes from a paper by Jordan and Kurtz. That paper is available online, It states the measured rate varies widely, from 0.23% to as much as 2%. And the mode among that data is between 0.4 and 0.5%, which you can see on page 4 of the paper.

So if the paper they quote says it is 0.5%, how do they get 1% from the same report? Because they chose the figure on the right of page 4, which includes low-quality data. And what is the difference between the two? Well, to quote the paper, the low-quality data is:

very sensitive to several sources of error that could skew the results. Soiling, maintaining calibration and cleanliness of irradiance sensors, module baseline data (nameplate vs. flash test), and not appropriately accounting for LID are just a few major sources of data errors.

In other words, the high-quality data is based on controlled measurements, where they account for these effects and report only the actual panel degradation. In contrast, the low-quality data does not account for these issues, so it includes all sorts of external environmental effects. They fail to mention any of this, and then knowingly use the bad data.

They also fail to mention that while the 1% value was indeed used by the industry in the past, they number the industry now uses is 0.5%. And that’s because a number of long-period studies demonstrated 1% was too high. In particular, an NREL study found that panels made before 2000 had a degradation rate of 0.5%, and those after 2000 fell to 0.4%. That indicates the sorts of improvement processes that continue to this day. And, of course, they have the LEEE-TISO numbers, which strongly agree with both of the sources quoted above.

Ferroni and Hopkirk then claim:

There are also other, external factors, which can reduce PV module lifetime, for instance the site, the weather and indeed climatic conditions. These aspects do not appear to have been treated in the scientific literature in connection with photovoltaic energy usage.

Oh, come on! They actually talk about these factors in the paper they’re quoting! These sorts of effects are also considered in every tool that predicts output, including PVWatts. And what, do they think their weather would be any different than the LEEE-TISO install down the road from them? Ugh.

…which brings us to…

Ok so now all of this feeds into this equation:

Screen Shot 2016-05-16 at 10.46.51 AM

What this does is add up all the yearly power production figures over the lifetime of the panel to produce the total energy output of the panel. And using their figures they get 2203 kWhe/m².

Ok, just for funsies, let’s run the exact same equation, but we’ll use NREL’s 30-year climatic data, and the industry-standard 0.5% degradation. That gets you 3795 kWhe/m². Almost double.

And I need to point out that I’m using industry standard numbers, and in one case, from the same paper they quote. Their result is lower simply because they have selected worst-case-scenarios for all of these numbers. Normally one would indicate this with error bars or use the mode or mean values like I’m doing here.

But they haven’t done that. They just say these numbers are correct. They aren’t.

So, now, the other side of the equation

Ok, so the authors have now developed a number for the total output of the panel, now it’s time to consider the total energy input. And that starts like this:

The average weight of a photovoltaic module is 16 kg/m2

As I noted earlier, the SolarWorld example I linked to above is 17.9 kg for 1.6 m², or 11 kg/m². I assure you this is typical, but feel free to Google “solar panel weight” if you don’t believe me. Then they go on to state:

and the weight of the support system, inverter and the balance of the system is at least 25 kg/m2

25 kg for every square meter? I’ve installed a number of crazy systems, and I can assure you, we never came even close to that. Invariably the heaviest part of the system was the panel.

So let’s check on their sources. Well, first of all they don’t actually quote the original source for those numbers, they quote a University of Toronto thesis from 2009 where you’ll find that:

Support structures for PV panels are made from aluminum or steel, with the majority of systems using steel.

The majority use steel? Uhh, no. And the 25 kg/m² figure in there? It comes from two even earlier papers from 2007. And when I looked there, the one that did have the 25 figure was quoting that from the other, which didn’t have that number in it.

I really have no idea where there this number comes from.

There’s only so much time we can spend on that madness. So let’s just use the power of the internet to find modern values. Check out page 6 of this fairly modern product guide to mountings, which puts the total weight of mounts and panels at 16 kg/m². If we use the modern figure of 11 kg/m² for the panel, that puts the weight of the support structure at 5 kg/m². That same guide also includes values up to 50 kg/m², but that’s for ballast on flat roofs, which are concrete blocks, not steel. This is not used on sloped roofs or ground mounts, but as it might represent as much as 15% of the market, you can factor that in as you wish.

Ok, let’s keep going.

16 kg (module) + 25 kg (balance of plant) + 3.5 kg (significant chemicals) = 44.5 kg/m2

Ok, let’s use our numbers from real sources instead: 11 + 5 + 3.5 = 19.5 kg/m²

Which brings us to:

Since the total lifetime energy return is 2203 kW he/m2, we obtain a material flow of 20.2 g per kWhe

Or maybe it’s 19,500 / 3795 = 5.1 g/kWh? Once again, using numbers from the industry I get a number four times “better” than they do.

Now, why is this important? Because that number is basically how you calculate the energy needed to make the panel and rest of the system. So much weight of steel takes so much energy to make, and so forth. So if you reduce that by four, you’re almost reducing the CED by four, right off the bat.

Show me da money!

So now the authors move onto the “use of capital.” The basic idea here is that money embodies energy, in a way. Basically, everything requires energy to build and ship to you, so if you spend $1 on something, some of that is paying for that energy. So, on average, you can say that a dollar of capital has a certain average energy content, which for convenience, we’ll express in kWh.

So if we’re going to start down that road, we need to have some sort of value for how much capital we need. Here’s the relevant part:

The actual capital cost for a sample group of fully installed PV units, 2/3 roof-mounted and 1/3 free-field-mounted, in Switzerland lies at or above 1000 CHF/m2 with large cost variations of up to 30%, due principally to the uncertainty in the price develop- ments of PV modules. The NREL (National Renewable Energy Laboratory of the U.S. DOE) reports capital cost for fully installed PV units in the lower end of the price range given above. The 1000 CHF/m2 cost, translated into specific cost for installed peak power is 6000 CHF/kWp and is a result of personal experience of the authors.

Ok ok, let’s take this bit by bit. First, they have a 2/3 roof and 1/3 field split. They don’t provide a source for that, of course. I’ve never seen numbers anything like this, and it is trivially easy to find industry values that show the opposite.

For instance, even in Germany where the majority of installs were residential, they represent only 35% of the total buildout. In the US, where the split used to be about 50/50, utility installations now far outnumber residential. I mention this because utility installs are ground-mount, so according to these recent sources, the total installed base should be at least the opposite of what they use in this paper.

And this is important because the capital cost of the system is roughly double for roof mounts, especially residential. That’s because you’re installing far fewer panels per job, so setup and administration are a lot more on a percentage basis. And for that reason, utility-scale installs are dwarfing residential these days, a move that continues to accelerate every year.

Which brings us to the second number, the actual capex value they will use from here on in. That number is 1000 CHF/m2, but that translates into 6000 CHF/kWp based on the “personal experience of the authors”?!

In a peer-reviewed paper, we’re being told just to take their word for it.


Well, they can’t be bothered to cite their numbers, but I’ll cite mine. I will refer to the most comprehensive and up-to-date industry-measured values one can easily get, the yearly Lazard LCoE report. And that number, averaged across the western world, is found on page 11, and it is $1500/kWp for utility and $3500/kWp for residential.

Using the modern 1/3rd residential, 2/3rds commercial split, that gives us (3.5*.33)+(1.5*.66) = $2145/kWp average. Now to make a kWp of panel using those SolarWorlds, we need 1000 / 280 = 3.57 panels, and since each panel is 1.6 m², we need 3.57 x 1.6 = 5.7 m², so on a per-m² basis that’s $2145 / 5.7m² = $376 / m².

That’s less than 1/3rd the number they’re claiming. Even this number overestimates the contribution of residential installs in the future. I prefer to use the utility rate as more indicative of the real capex of PV; $1500 / 5.7m² = $263 / m².

Working in a coal mine

The paper then moves on to breaking out the various components of that cost and calculating the energy value of each one. They start with labour. After quoting four-year-old figures, they say:

Based upon the authors’ experiences for typical local labour costs per square meter of PV module are: project management (10% of capital cost), installation (506 CHF per m2), operation for 25 years, including insurance (1.67% of capital cost per year for 25 years) and decommissioning (30% of installation). The total labour costs amount to 1175 CHF/m2.

Now in case it’s not obvious, I want to point out that all of these measurements are based on the capital cost. So if your capital cost is off, this is too. And their capex is off by a factor of three to four. Because, once again, it’s just “the authors’ experiences”.

And to make my point, consider that value in the middle, the installation costs. They’ve already said that the total capex for the system is 1100 CHF / m², and here they say that installation labour is over 500 of that, roughly half.

Really? According to these numbers, published only months ago, all soft costs put together cost around 52% of the system price. And you’ll note that number puts all-in prices at 1300 Euro, basically identical to the Lazard number at $1500 US, and, once again, 1/4 the number Ferroni and Hopkirk create out of thin air.

So again, let’s ignore their made-up numbers and use these industry standard ones. They calculate 505 kWhe/m² based on 1175 CHF/m² of labour. Using these figures we see that all the soft costs are 52% of 1300 Euro per kWp, or 748 CHF/kWp, or 209 kWhe/m².

But what’s another factor of two between frenemies?

And finally, in section 5.5.3, the duo calculate the energy value of the capital itself. Basically, the idea here is that if you have to borrow the money (or you can flip that to opportunity cost, same thing) then you could express that in terms of panels you could have bought with that interest (so to speak). You can think of that as “lost energy” in a way…

  • Using their rate of 1100 CHF/m², they get a value of 420.
  • Using the industry rate above, 1300 Euro/kWp, that gets us around 120.

Show me da money (again)!

Which brings us, finally, to their totals in Table 4:

Screen Shot 2016-05-16 at 12.13.34 PM

Now let’s do the exact same thing using the numbers we’ve calculated:

CED 1300
Integration 349
Labour 209
Faulty equipment 90
Capital 120
Total 2068

So basically, just considering the known-good, widely-available capex number, we’ve reduced the “energy investment” by 22%.

All of this goes back to the original claim. They claim that the ERoEI is 2203/2664 = 83%. But a whole lot of that is made up by the cost of capital, based on a bogus number. By changing that one number to the one actually measured in the field, we get 2203/2068 = ERoEI 1.06.

And if we instead insert NREL’s number for the insolation, and use the industry standard degradation, it becomes 3795/2203 = ERoEI 1.7. That’s better than fracked oil in the US.

And we haven’t even touched that CED number, which, as you can see above, is based on some rather odd numbers about system weights.

That’s not all folks…

Now we come to the issue of recycling. In the calculations in the paper, the authors consider the panels to have a 30% decommissioning fee, which is added to the labour term.

But they totally ignore the salvage value of the panels. Panels are basically glass, aluminium, some silver and some copper. People pay for these things, which is precisely why the Europeans have a recycling program for panels, one they even talk about in their paper.

Given an average 50% energy recovery for recycling, we can reduce the CED of a 2nd generation panel to 650. Running the same calculation gets us 1419, so 2203/1419 = 1.55, or 3795/1419 = 2.7.

And if you do consider the recycling as a potential revenue stream, then the labour line is reduced by some portion of that 30%, which brings the denominator to 1340. And that gives 2203/1340 = 1.64 or 3795/1340 = 2.83.

So in the end

Consider this: the calculation they use in their paper would produce different results if the interest rate changes, the FX rate between the Yuan and Swiss Franc changes, or the price of installations continues its astonishing downward fall.

So, what exactly is this figure measuring?

It’s certainly not measuring anything like the “embedded energy content” of the panels. That wouldn’t change just because someone types a number into a Bloomberg terminal. Yet that’s precisely what happens using their calculation.

And finally, I need to point out the glaring fact that the authors don’t run the same calculation on any other power source. Given that sources like nuclear are far more capital intensive than PV (which is why no one is building them) their calculation of “ERoEI” is worse.

This paper is just plain bogus. The entire methodology is based on numbers that have no physical reality (money) and the authors deliberately cherry pick data to make those numbers “prove” their point, or just make up values out of the air. All of this is glaringly obvious, and is simply yet another example of the sorts of attacks renewables face at the hands of the true believers in the nuclear field.


1. sod - May 17, 2016

Thanks! Very good convincing work!

MuellerB - May 19, 2016

You can also look at the material intensity which they claim to have from a british nuclear power station, which is also bogus (see the comments to euan mearns artcle), if you look into the document the numbers there are totally different and about 30 times hgher.
If you take the real numbers of the document it is about 15g/kWh for nuclear power, and according to your calculation about 5g/kWh for solar power.

Maury Markowitz - May 19, 2016

I think it’s very telling that the original authors did not run the same calculations for any other power source, notably nuclear. I am currently working up a set of spreadsheets for this.

2. singletonengineer - August 17, 2016

Picky, I know, but where is the inverter efficiency included in your numbers? I was quoted 80% for a domestic system earlier this year. That would be a lower limit for commercial scale installations… would 85% be close?

Maury Markowitz - August 18, 2016

Great question! Warning: I’m replying on my iPhone so forgive me for any errors!

The inverter efficiency is in the capacity factor. Pretty much everything is; snow, wire losses, inverter losses, even dirt on the panels. In the past, NREL used a derate of 23%, meaning they expected that much loss after the panel. That was based on inverters with efficiency on the order of 85%. But the last 15 years have changed that dramatically, modern string inverters have peak numbers around 98% and averages well over 93%. This is largely due to the improvement, and especially price reductions on modern IGBTs and thyristors with allow higher frequency operation. As a result, NREL finally updated their apps to use a total derate of 17%. That said my own system outperforms even that, which is common for small systems using micros or optimizers. So inverters used to make up just less than half of the derate in the past and now it’s the same as the effect of dirt.

So my advice is to use 90, but be sure to go to the PVWatts page and click on the link beside that number so you can see all of the inputs and play with them.

Maury Markowitz - October 26, 2016

And a further update: NREL has once again reduced the derate to a mere 14% in the latest version of PVWatts.

3. Abhilash - October 25, 2016

Thanks for the informative deep dive. Hard work like yours helps me keep my head above the metaphorical waters. Cheers!

4. Ugo Bardi - October 25, 2016

Hello, Maury. Can I reproduce your post in my blog? (www.cassandralegacy.blogspot.com

Maury Markowitz - October 26, 2016

I’d be honored! Out of curiosity, I noticed a big spike in traffic on this article today, but no obvious single source. Has it been pointed at from another site somewhere?

WattisDuurzaam - October 26, 2016

The Ferroni and Hopkirk article has been cited to justify the claim that solar panels are ‘energy sinks running on coal power’ in a Dutch national newspaper last Saturday. That might have helped. 😉

Maury Markowitz - October 26, 2016

Ah yes that sounds like it.

Ugo Bardi - October 28, 2016
5. Sanjeev Ghotge - October 26, 2016

Excellent work, Maury! Keep nailing the lies!

6. The Truth Is In The Footnotes - October 28, 2016

I appreciate your thorough dissection of this article, your use of logic, reason, and a healthy skepticism, and the relative lack of vicious profanity and name calling. You even display a sense of humor (and adorable graphics) which makes work much more pleasant to read than the typical rant. Bravo! Your occasional use of Italics and the word “bogus” seems like an entirely reasonable reaction to such obvious procedural gaffes on the part of the authors.

However, I detect a significant bias in your approach. As seen above, you can patiently excoriate any material you find questionable, yet in your other musings you enthusiastically quote from NREL and other pro-PV articles as though they were “golden”. I submit that if you performed a similar examination of any of those you would find they all have similar deficiencies in methodology and references as the article you were critiquing above, some much worse.

I have been collecting data for a design study of a “ground up” input/output flow chart for a solar “breeder” process. So far I have examined more than 300 articles from the pro-PV power industry for info on the total energy and material inputs, and found even the most “comprehensive LCA” to be useless for the purpose of documenting a valid model for solar breeding. In their determination to prove a “positive energy balance” the authors omit critical steps in the production processes, significantly undervalue energy inputs, ignore material losses, fail to account for in-process recycling and many other energy values that make up the actual process, for good or bad.

If you actually read the NREL and other pro-PV references carefully for disclaimers (check the footnotes) you will find that many articles are not actually “studies” of any real data, but “predictions of future performance”, and the conclusions are based largely on substituted values or estimates. Often, when “real values” are claimed, they are “averaged” and no source is given. The few articles that claim to use empirical data also includes substituted data at less the correct value, and the boundaries are limited. Several of the authors cite their own previous work and that of their co-authors as references for each other in what appears to me as a “round-robin” of self-reinforcing delusion (or deception?) which is all based on a more-or-less imaginary or incomplete foundation.

When I attempt to add back in the energy values all of the (intentionally?) missing pieces of the puzzle using data reported from the primary industries involved, it looks to me like the total energy needed to stamp out these little PV puppies in the real world is many times the amount that they will ever produce. So, all other issues aside, it appears “solar breeding” will never be remotely possible, based solely on a profoundly negative “energy balance”. Therefore, when the non-renewable energy sources are consumed, the “renewable” sources will expire as well.

What say you to these charges? Would you be able to set aside your bias and examine your sources critically? Would you be willing to use you commendable intellectual powers for discovering the “truth”, even if it contradicts your previous conclusion? The true Scientific Method demands that you do so, but can you? I await your response with interest, and I thank you sincerely for you consideration.

Maury Markowitz - October 28, 2016

I await the chance to review your article!

The Truth Is In The Footnotes - October 29, 2016

Outstanding! The finished article will be a while yet, but I am looking forward to your dissection of it. Most likely, I will need to break all of that down into 3-4 articles, each making a specific argument. I am hopeful that if you examine my article(s) like you did above, you will either confirm my findings, or bury me with “boguses” and italics and sarcastic memes… and save me the embarrassment of attempting to publish something without merit. In the meantime, would you be willing to review the deficiencies of just a few of the articles I mentioned, and perhaps look at some rough calculations? I think you may pick up on the main issues right away.
Thanks again.
P.S. apparently my r key is flaky. apologies for the typos.

Maury Markowitz - October 31, 2016

I’d be happy to look over what you’ve collected. I will filter, however – any article more than five years old I won’t bother with. It is outdated, by definition, as outlined above.

The Truth Is In The Footnotes - November 6, 2016

“I’d be happy to look over what you’ve collected. I will filter, however – any article more than five years old I won’t bother with. It is outdated, by definition, as outlined above.”

Hi Maury, are you sure? One of the most-referenced pro-PV articles is the NREL “PV FAQS” http://www.nrel.gov/docs/fy04osti/35489.pdf

You even linked to it as a “pro-PV” reference in an earlier post. It was published in 2004, and the articles it uses as references were published in 1998, 1997, 1997, 2000, and 1991.

Maury Markowitz - November 6, 2016

It appears I cannot reply to a reply in this UI, so I hope you can see this. I should have been more clear in my post – the numbers that need to be modern are economic ones. That said, this paper *is* getting a little long in the tooth, kerf losses are *way* down and energy in mono has gone down somewhat. I’ll start looking for a better one.

7. steve - October 28, 2016

SO glad Ugo reproduced your post. I started following the Euan Mearns blog a while back, and don’t have the background ( or time) to determine how solid the information is. Thanks for your work.

8. Uku Uujari - October 31, 2016

Up to 10 year old panels are all relatively new, if the life cycle of the panel is considered to be 20+ years. It is good to know, that the most modern panels can produce more power, than was consumed by building those panels, but if the average of the last 10 years is still opposite, then it does not show solar panels in good light.

Rather than theoretical values, the empirical values for power production per square metre should be used. I checked many public real installations close to Zurich (from https://www.suntrol-portal.com/en/plant/search/browse), and I found no single installation, that has produced 170 kWh/m2 per annum.

Reduction of energy costs because of possible energy regain from recycling is not correct, if to consider how those mountains of demolished panels are piling up.

Maury Markowitz - October 31, 2016

> Up to 10 year old panels are all relatively new

In terms of that panel’s lifetime, yes, but in terms of a baseline for the performance of panels in general, no. As the vast majority of panels are three years or newer, any statistic based on any data older that that is skewed, by definition. It would be like talking about gas milage of cars in the US by averaging ever car made since the 1960s.

> Rather than theoretical values, the empirical values for power production per square metre should be used.
> I checked many public real installations close to Zurich

Interesting, let me try it. Ok, using the web page you posted I found one installation in the area that is relatively new:


According to PVWatts with a 14% derate and 40 degree average pitch, this system should produce 13,759 kWh per year. It has been running since March (I’m assuming yyyy-mm-dd) which is 237 days of 365 = .65 of a year. It has produced 10,166 kWh, so pro-rating that over the year gives us 10,166 * (1/ .65) = 15,640 kWh/year. So this system is outperforming the estimates, by a good amount.

Perhaps you are using PVWatts incorrectly? Did you account for the mixed, non-ideal pitch angles? I can step you through it if you’d like.

Uku Uujari - October 31, 2016

It is not the wisest thing at all to estimate annual production by only results of few summer months! This kind of speculation leaves far behind every possible speculation that one might find from the report by Ferroni and Hopkirk.

Please note, that most of actual installations are producing only 110…140 kWh per m2, althouhg they are mostly under 5 year old.

Maury Markowitz - October 31, 2016

And it’s not the wisest thing to estimate “mid latitudes production” based on Switzerland’s almost-all-BIPV installs. When you have solid numbers on a utility-scale install in the area, I’m all ears. Hmm, reply threading on WP leaves lots to be desired.

Uku Uujari - October 31, 2016

Even if to be over-optimistic and to add total 2000 kWh for missing 4 winter months, then the installation you selected, will not exceed 140 kWh per m2.

Uku Uujari - October 31, 2016

What scale is utility scale?
https://www.suntrol-portal.com/en/plant/search/advanced let you select installation even by the system size.

Uku Uujari - October 31, 2016

Is this installation in utility scale enough?

Uku Uujari - January 21, 2017

So far your selected installation https://www.suntrol-portal.com/en/page/pvdobler is in trend to achieve 125…130 kWh per m2 per year. That is much closer to 110 kWh/m2, suggested by Ferroni and Hopkirk, than to 170 kWh/m2, suggested by you. It is only 50 days short from the first complete year of operation, and the total production of the last 50 days is ca 315 kWh. So the pessimistic yearly output will be ca 10,840+315= 11,155 kWh. Optimistic yearly output could be 12,500 kWh (if to assume, that during the next 50 days those panels will produce 5 times more energy than last 50 days), but even this is far from 13,759 kWh per year, predicted by PVWatts’s, and even more from yours utopic 15,640 kWh/year.

Uku Uujari - March 12, 2017

Today, on March 12 at 9:10 AM, the first 365 days of operation of the Pvdobler’s solar station was completed.
Total energy produced during the first “year” of operation was 11,826.12 kWh.

My optimistic prediction (from October 31) was 2.87 % higher – 12,166 kWh.
The mean of my optimistic and pessimistic predictions from January 21 was extremely precise, (11,155+12,500)/2=11,827.5 kWh (the error margin was only 0,01%).

The prediction by PVWatts (13,759 kWh) was 16.34% too high.
Your prediction (15,640 kWh) was 32.25% too high.

The actual production per m² per annum was 134.4 kWh.
Ferroni and Hopkirk claimed, that the average for the region is 106 kWh/m² per annum. That was 21.12% less than the yield of the Pvdobler’s solar station and this was not so bad if to consider, that you especially selected the solar station, that was very new and had shown it’s initial productivity that was above the region’s average.
You claimed, that an average annual production for the region is 170 kWh/m² (177.7 kWh/m² for the Pvdobler’s solar station). That is 26.5% (32.3%) higher, than the actual yield of the Pvdobler’s solar station.

So, let’s say that at least the myth of 170 kWh/m² per annum is busted!

Anton Boonstra - May 12, 2017

[quote]So, let’s say that at least the myth of 170 kWh/m² per annum is busted![/quote]
Nope. If you look closer, you can see this installation uses 3 different orientations. Along with the south orientation, also the not ideal east en west orientation.

If you look at the outputs per string/MPP, you can also see that before June 20th 2016 only one string was active. So the complete installation of 14,3 kWp has not been active for a full year.

Uku Uujari - July 28, 2017

Anton, I did not choose this installation! Mauri did, and presented this installation as an exsample of installations, that can produce 170 kWh/m² per annum. He claimed, that 170 kWh/m² per annum is an AVERAGE productivity of real installations! So we talk about productivity of real installations, not theoretical maximum of ideal installation.Real installations are not in ideal conditions.

9. Uku Uujari - November 1, 2016

Should all those energy costs to be included when calculating the cumulative energy demand? Is there something missing?

Calorific value of the raw materials / packagings / wastes
Mining, drilling of raw materials
Reclamation of depleted mines / oil and gas lands
Transportation (ores, crude oil, gas)
Processing of the raw materials (metals, silicon, plastic, etc.)
Waste disposal (raw materials), cleaning of exhaust gases and waste waters
Packing, tare (raw materials)
Warehousing and logistics (raw materials)
Transportation (raw materials)
Actual production of solar cells and panels in the plant
Waste disposal (production), cleaning of exhaust gases and waste waters
Packing, tare (solar panels)
Warehousing and logistics (solar panels)
Transportation (solar panels)
Installation, base, fasteners, inverter, wiring, relays etc.
Maintenance, cleaning (snow, leaves, algae, dust, etc.), repair
Dismantling of the depleted device
Transportation to the recycling station / landfill
Waste disposal at landfill

Maury Markowitz - November 6, 2016

Absolutely! Please provide all of these numbers, along with similar numbers for two other sources of your choice, although I’d personally prefer wind and nuclear as the two.

10. lukas boehler - January 7, 2018

Thank you for this work. Next time I’m confronted with the stupid results from this paper i know the fact’s and must not dive into de details.

We are trolled by nonsens information today which were widly spred. Mr. Ferroni made a newspaper article out of this paper! Same happends whith climate change and EV’s.

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