ECD: Better or Worse? (ENER)
ECD has created a shiny new presentationto introduce interested parties to the company. It is an excellentillustration of what Energy Conversion Devices are all about. Let usfocus, specifically, on the "better real-world performance" claim madeon slides 10 and 12.
According to these slides, Unisolar’s "amorphoussilicon triple-junction" product dramatically outperforms virtually anyother PV panel on the market – from "dual-junction amorphous silicon"to monocrystalline silicon. It is all bogus, of course. In the realworld, on real roofs, Unisolar’s glued-on laminates should rarelyoutperform optimally-tilted rack-mounted glass PV panels (whetherthin-film or crystalline), and the initial energy-yield advantage, ifany, should typically be gone within a few years, mostly due to long-term degradation issues.
The first thing one should notice on Slide 10 is that the yellow bar labeled "Avg. a-Si Double Junction" appears too tall. That bar is actually only 29% shorter than the red UNI-SOLAR bar, not 41% as the label claims. Turns out that the bar labeled "Avg. Poly-Si"is also a bit taller (it is only 15% shorter than the Unisolar bar, not18% shorter as labeled). Thus, the bar chart drawing appears tovisually penalize Unisolar’s "relative performance." So was this somekind of a Freudian slip or simply an innocent alteration to make the chart look nice?
Slide 12 supplies the "supporting data" for the chart. According to that slide, "USO [that is, United Solar Ovonics] outperforms: Mono-Si by 11%, Poly-Si by 18%, CIS/CIGS by 24%, DJ a-Si by 41%."The source is indicated as "Tucson Electric Power, Arizona, USA," thesite, as "Tucson, Arizona, USA." And, specifically, the average annualyield (2004-2007) of Unisolar’s "a-Si TJ" is shown as 1,757 kWh/kWp, while the "avg. mono-Si" is 1,588, and the "avg. poly-Si" is 1,491. So far, so good.
Now,go back and carefully read the Safe Harbor (slide 2). All thedisclaimers there are about forward-looking statements. But what aboutpast ("historical") information and statements? What about slide 23 presented at the Investor Day last year, and a subject of the first post in the "kWh/kW myth" series in this blog?
On that day, investors were told that "Tucson Electric Power report[ed]" that Unisolar had 1,757 kWh/kW average annual yield, mono-Si, 1,686, and poly-Si, 1,492.
The 1,757 Unisolar number is the same in both the "Introduction" and the "Investor Day" slides, but the mono-Si number is different (1,588 vs 1,686) and so is the poly-Si number, by just a tad (1,491 vs 1,492).So when did ECD tell the truth, on October 2nd, 2008 or, a year later,on October 12th, 2009? Let us look more closely at the data source.
Tucson Electric disclose, on their web site,the underlying raw monthly and yearly kWh data (in pdf files) for manysystems they have monitored at their Springerville station (SGS), theirOperating Headquarters (OH), as well as some customer locations, butthere is no specific report there comparing Unisolar’s performance withthose of other systems for the period 2004-2007. In fact, that raw setis plagued by some incorrect entries (for example, the Shell/Siemens ST40panels that comprise the 1440W system at the OH are not a-Si as stated- they are CIGS, and the Astropower system at OH is not a round 1500Wbut a bit smaller – 1485W or 9 x 165W). In addition, there have beenvarious panel replacements and inverter changes and modifications (theTrace inverter of the Unisolar system, for example, was apparentlyreplaced by a Fronius inverter sometime in 2005). Finally, it should benoted that only the SGS systems were truly monitored on a real-timebasis (while data was collected manually for the OH and the rest of thesystems, see pages 33 and 36 of the 2006 Annual Report). The tablebelow is an attempt to provide a clean dataset (showing only systemsthat had non-zero kWh generation in each of the 48 months in the period2004-2007, although an exception had to be made for the mono-Sisystems).
So, what do the data reveal? The "average" 2004-2007 kWh/kW energy yield number for small systems (basically, at OH) was 1,590 for mono-Si (one AstroPower and one Shell system, but the data are not clean), 1,532 for poly-Si (three BP/Solarex, one Sharp, and one Kyocera system), 1,445 for CIS/CIGS (one Global Solar and one Shell/Siemens system), and 1,273for DJ a-Si (one BP/Solarex system). The respective "averageoutperformance" by Unisolar is 11%, 15%, 22%, and 38% – thesepercentage numbers are not much different from what ECD show in theirslide. Great!
But the data from the large systems, which are monitored more reliably, show the poly-Si’s average as 1,723 (ASE systems), and DJ a-Si’s as 1,524(BP/Solarex systems). Unisolar’s "average overperformance" is just 2%and 15%, respectively, and, nowhere near the 18% and 41% numbers in the"Introduction."
Moreover,take a look at the yearly outperformance percentages for each small OHsystem, separately. Do you notice how they jump (7% to 18%) between2005 and 2006 for each OH system, except Sharp, and then continue toincrease in 2007 as well? The change of the Unisolar inverter sometimein 2005 might have had something to do with it (Sharp was the othersystem that had an inverter replacement that year – notice the 60% jumpin 2006?). In year 2005, Unisolar outperformed mono-Si by 5%, butUNDERPERFORMED large-system poly-Si by 2%. And it performed on par withFirst Solar’s CdTe large system (no wonder ECD, who lost the thin-film race, never mention First Solar in the entire "introductory" presentation).
But that’s not all. The 2003 Tucson Annual Report reveals on page 40 that "modules are facing due south at an angle of 34 degrees from horizontal, which is latitude angle"(describing the SGS large-system set-up, but the OH set-up at Tucson isprobably similar, with possibly slightly-lower tilt, as the latitudethere is 32 degrees). It appears that the Unisolar modules used in this"study" were the tilted, framed US-64 panels, discontinued in November of 2007. Why would ECD’s introductory presentation rely on performancedata from modules they no longer make and sell? Couldn’t they find someindependent, side-by-side long-term performance data for the PVLsystems they have been selling since 1997?
Luckily,there might be a way to estimate the hypothetical performance ofUnisolar’s PVL products which typically lie glued to a flat roofwithout any ventilation. The analysis of another dataset (Santa Cruz,CA, located at 37 degrees latitude, 600 miles west, but just 5 degreesnorth), again a subject of a previous postin this blog, reveals that in the period 2005-2008, the30-degree-tilted Unisolar framed modules (US-116) outperformed theno-tilt glued-on Unisolar laminates (PVL-128) there by 24% in 2005, 26% in 2006, 27% in 2007, and 27% in 2008 (yielding 1,607, 1,573, 1,647, and 1,628if Tucson Electric had installed a system with Unisolar’s current product line (the PVL series) glued to a flat roof, then, in fact, the Unisolar system could have UNDERPERFORMED allthe tilted rack-mounted panel "average" systems (mono-Si, poly-Si,CdTe, Sanyo’s HIT, and, yes, even CIGS and the large BP/Solarex a-Sisystem), except the small OH BP/Solarex a-Si system (but note thatTucson Electric complained on page 42 of their 2003 Annual Report that the "BP a-si modules have been challenging" due to issues with voltage mismatch at the inverter, while in other studies, those modules had been plagued by corrosion and delamination). kWh/kWp, respectively, or underperforming the Tucson set-up by just 3%in 2005, explained by the lower solar irradiance 5 degrees north, butby 11% in 2006 and 2007, adding further evidence that something couldhave gone wrong after the inverter change in 2005 at Tucson). Isn’tthis interesting? It turns out that
Specifically, assuming a 25% outperformance of Unisolar’s tilted framed modules vs the glued-on laminates, and even ignoring the possible data contamination from the inverter change, the "average underperformance"by Unisolar’s flat-roof "BIPV and BAPV" products would come to 11% vstilted mono-Si, 8% vs small-system tilted poly-Si, 2% vs tilted CIGS,18% vs large-system tilted poly-Si, and 8% vs large-system tilted DJa-Si, based on the Tucson, AZ data. In other words, a glued-onBIPV/BAPV Unisolar system would be underperforming (in terms of energyyield) virtually any optimally-tilted rack-mounted glass PV rooftopsystem, even before the long-term degradation sets in.
Thus,it appears that neither the "Investor Day" slide nor the recent"Introduction" slides fairly represent the energy yield(under)performance of Unisolar’s current glue-on-laminate line ofBIPV/BAPV products. Consequently, any return-on-investment or LCOE calculations that had relied on such representations might benefit from a careful re-evaluation.
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