By Girolamo Di Francia, ENEA & EU-PVTP expert, Italy

Introduction

The photovoltaic (PV) sector has now reached a good maturity characterized by a worldwide installed capacity of 180 GWp, increasing at a constant rate of about 35 GWp/yr during the last three years and by an annual turnover of about 45 B$, a trend that also seems confirmed for the current year. More than 85% of all the PV plants are realized by means of PV modules based on crystalline and polycrystalline silicon (cSi solar cell technology), an industrial sector dominated by Chinese companies with a 60% of the market share. In comparison, less than 20% of the photovoltaic modules are produced in the European Union (EU) and the United States (US). Vice versa EU and US are the most relevant markets for photovoltaic products with almost 70% of the installed capacity being located in those areas (EPIA 2013, Eurobarometer 2015).

On the history and the development of such a strongly unbalanced situation, several papers have been published (see for instance: de la Tour, 2011). As a matter of fact, the question is not a minor one. Photovoltaic is indeed an important product segment of the semiconductor industry, accounting, in 2014, for about a 5% of the whole 300 B$ sales of this sector and, by now, rapidly becoming comparable to other more confirmed electronic device markets, such as those related to memories or analog devices. A very intense debate is, therefore, in progress focused on the possible strategies the US and EU should undertake in order to revitalize their photovoltaic industries so that a more suitable equilibrium between China and EU/US production is set. In this respect, it seems natural to try to learn from the historical development of the electronic industry, if similar problems have occurred in that case, and if the solutions they implemented could be transferred to the photovoltaic case.

Table 1. 2014 world leading photovoltaic manufacturers

Company	Country	Location of production lines
Trina Solar	China	China
Yingli Green Energy	China	China
Canadian Solar	Canada, China	Canada, China
Jinko Solar	China	China
JA Solar	China	China
Renesola	China	Poland, South Africa, India, Malaysia, South Korea, Turkey, Japan
Sharp Corporation	Japan	Japan, US
Motech	Taiwan	Taiwan, China, Japan, USA
First Solar	US	Malaysia, US
Sun Power	US	US, Philippines

Indeed, a similar situation occurred in the US semiconductor industry in the late 1980s, when it had become evident that the competition with Asian electronic chips manufacturers (memories and analog devices) was going to be lost. Most of the US electronic companies decided then to shift their production from that class of chips to new products (mainly microprocessors), also through the support of national governments initiatives. This change of approach was sustained by a growing demand for the new products that, in turn, supported the creation of a local industry of production equipment specialized for those kinds of applications (Pillai 2014). Product innovation was, therefore, in that situation, the solution to cope with the asian competition, at least temporarily.

Discussion

Whether this approach can be applied to the PV industry, as well, and innovation in solar cell technology be used to revitalize the US and EU photovoltaic industries is, however, a matter of debate. Before that paradigm can be adopted, it is important to understand the extent that the photovoltaic and the electronic sectors are similar and, in this respect, a few issues need to be more deeply discussed.

1. Technological issues

Although the basic material and processing technologies are similar, the actual fabrication processes for a cSi solar cell and an electronic chip are very different, as shown in Table 2. In the case of a solar cell, a single device is obtained out of the processing of a single silicon wafer (true large area devices) while in electronics, thousands of chips are fabricated on a single substrate (high volume production). Of course, device processing resolution requirements are also very different. For a solar cell, the minimum line to be processed is, at most, in the hundreds of microns range, while for a memory chip even less than 20 nm could be required. Both resolution and number of devices to be processed per single wafer change, in turn, the basic Fabrication Yield (FY) requirements for the two devices: for a solar cell, the FY is mainly limited by wafer handling failure, with less concern with the fabrication environment.

Table 2. A comparison of the main features of a solar cell and an electronic device

	Photovoltaic	Electronic
Basic Fab. Proc.	=	=
Large Area	True large area	High volume
Resolution	0.1 mm	20 nm
Reliability	25 yr/80%	5 yr (Memory card)
Operating Conditions	-40 °C/+80 °C	-10 °C/+50 °C
Fab. Yield Limit.	Handling	Wafer processing

For an electronic device, particle contamination control is critical, perhaps even more than wafer handling, and highly controlled environments (clean rooms ISO 1 and ISO 2) are mandatory. But it is, perhaps, in terms of device reliability that the two classes of devices mainly differentiate. A solar cell has to continuously work for at least 25 years in an operating temperature range that can change from – 40°C up to + 80°C, and with an end life efficiency that has to not be less than 80% of its starting one. On the contrary, an electronic device, a memory card for instance, is warranted to operate for about five years and in much less stringent operating conditions (-10 °C up to + 50 °C). It is worth noting, in this respect, that for many other electronic devices (mobile phones for instance) the full functionalities are assured for not more than two years.

2. Product innovation issues

In the electronic sector, the capacity a new product has to enter the market is, first of all, connected to its innovative performance, perhaps even more than to its cost. Let us, for instance, consider again the case of memory cards, one of the most reliable devices, as stated above. As shown in Figure 1, in the last 12 years the average product has increased its performance by a factor of 1,000, increasing its capacity from an average of 128 Mb in the year 2003, to today’s 128 GB.

Correspondingly, a twofold decrease in the cost/Mb has been observed, although in this same period a more limited decrease in the average product cost is actually observed (McCallum 2015).

On the contrary PV solar modules have experienced in the same period a one fold decrease (from 6 $/Wp to 0.6 $/Wp) in their average cost, but the conversion efficiency, the main technological characteristic fingerprint of the innovation for this sector, has only observed a modest 30% increase (see Figure 2).

Innovation, therefore, does not seem to have played a key role in the development of the photovoltaic sector and, effectively, it has been reported that the major role in PV cost reduction is due to economies of scale (ISE 2013, Goodrich 2012).

Conclusions

Sic reris stantibus, it is questionable to what extent innovation in the PV sector can effectively support the further diffusion of this form of energy and help the EU and US industries cope with the Chinese competition. Recently, for instance, it has been observed that while a certain level of product innovation can be necessary, excessive innovative technological scenarios could even be detrimental (Goodrich 2012) with respect to a more capillar photovoltaic diffusion.

The point that is important to keep in mind is that the end user of a PV module is an energy producer, and since the fuel (the solar radiation) is available at no cost, once the system used for the conversion is such that the cost of the electricity produced becomes competitive with that of other energy sources, as it is now effectively observed in several countries, the only other issue to be considered is the long-term system reliability. As the solar modules actually on the market have shown in the last 40 years, to fully comply with this requirement, it is difficult to conceive an innovative product capable of revitalizing the US or EU photovoltaic industries that is, at the same time, truly different from that classical, very sound, product. Finally, it is worth noting that it has also been demonstrated that there is no practical economical advantage in setting up a PV industry in China with respect to any other US or EU region (Goodrich 2013). This suggests that revitalizing the US or EU industries could be more a question of further supporting the diffusion of photovoltaic energy than of pushing too hard on the innovative character of the PV productions. In this respect, it is perhaps more urgent to find innovative financial schemes, sustainable from the point of view of public spending, and also capable of supporting the expansion of a sector that has become relevant for EU and US industrial and environmental policies, than to pay too much attention to the innovative characteristics of a product that seems, at present, to fully satisfy most market expectations.

References

de la Tour A., Glachant M., and Ménière Y. 2011. Innovation and international technology transfer: The case of the Chinese photovoltaic industry, Energy Policy 39 (2): 761-770.

EPIA Global market outlook for photovoltaics 2013-2017. Available at: http://www.epia.org/fileadmin/user_upload/Publications/GMO_2013_-_Final_PDF.pdf

Eurobarometer 2015. Barometre photovoltaique Eurobserver Avril 2015. Available at : http://eurobserv-er.info/photovoltaic-barometer-2015/

Goodrich A., Hacke P., Wang Q., Sopori B., Margolis R., James T.L., and Woodhouse M. , (2012) A wafer-based monocrystalline silicon photovoltaics road map: Utilizing known technology improvement opportunities for further reductions in manufacturing costs. Solar Energy Materials & Solar Cells 114: 110–135

Goodrich A., Powell D. M., James T. L., Woodhouse M. and Buonassisi T., (2013) Assessing the drivers of regional trends in solar photovoltaic manufacturing. Energy Environ. Sci., 6 : 2811-2821

ISE-Photovoltaic Report, Photovoltaic Report 2014, Ise Fraunhofer, 2014.

McCallum J.C. 2015 Flash Memory Prices (2003-2014). http://www.jcmit.com/index.htm (last accessed june 2015)

Pillai U., Querques N., and Haldar P. 2014 The U.S. Photovoltaic Manufacturing Consortium: Lessons from the Semiconductor Industry. InterPV.net – Global PhotoVoltaic Business Magazine. Available at: http://www.interpv.net/market/market_print.asp?idx=666&part_code=03