Grid parity entering “inflection zone”

Applied Materials sees a “zone of inflection” starting around 2011-2015 during which time the levelized cost of energy from PV technologies will start to equal and then go lower than conventional electricity rates, in a presentation of the company’s PV technology strategy at a technical symposium jointly sponsored with the IEEE SCV-EDS society.

Applied Materials’ Mark Pinto, SVP/GM, energy and environmental solutions, sees a “zone of inflection” starting around 2011-2015 during which time the levelized cost of energy (LCoE) from PV technologies will start to equal and then go lower than conventional electricity rates (see Fig. 1), in his presentation of the company’s PV technology strategy at its technical symposium (Oct. 2, Mountain View, CA) jointly sponsored with the IEEE SCV-EDS society.

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Figure 1. Grid parity: the inflection zone. Assumes good sunshine (1800 hrs), 7.5%/year cost/W reduction for PV. (Source: Applied Materials)

Pinto pointed out that if the installed price of solar is <$4/peak watt (Wp), it is possible today to meet a target price of $0.20/KWhr (10% of the world’s total price of electricity falls into this category) with large scale installations of thin film-based PV technology. If the price of electricity is $0.15/KWhr, the average price in California today, one could meet an installed price of <$3/Wp provided a forward-going contract is established — i.e., the projected cost of what a factory will output in the next 8-10yrs would have to be <$0.15/KWhr. And with a target price of electricity at $0.10/KWhr, more than 50% of the world’s total today is at this value, it’s possible to get to production costs at that level over a forward period if feed-in-tariffs (FITs) or other kinds of government-based incentives are included.

To drive down the cost of PV technology, Applied is attacking its two components: module cost and installation cost. Module cost, i.e., cost/W, comprises materials and process costs and module efficiency. Installation costs comprise module efficiency, module size, module weight, labor cost, and site costs. Strategies for thin-film and crystalline PV are different.

For thin-film PV modules, Applied is leveraging both low cost/area processing and reduced installation costs that are the direct result of using large substrates. Pinto cited SunFab data using 5.7m2 substrates, for which the company says it has obtained an ~20× reduction in display cost/area. Another advantage to using the large area substrates is the attendant reduction in installation costs by system integrators who measure cost by $/Wp for the whole system. Pinto said that the 5.7m 2 size glass results in a balance of system savings >17%. “It’s equivalent to a more than 2%-3% gain in efficiency,” he noted.

On the process side of thin-film, Applied is on track to achieve 10% cell efficiency within the next two years (see Fig. 2). According to Pinto, the company is working on three key areas to meet its roadmap: 1) improved light capture by the optics, 2) improving the PECVD processing (i.e., better materials) for the absorber layer, and 3) reducing the resistivity while increasing the reflectivity of the contact materials.

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Figure 2. Driving thin film silicon efficiency at large scale. (Source: Applied Materials)
Pinto presented an example of the SunFab tandem junction cell produced on 5.7m 2 modules — it has achieved an initial cell efficiency of >10% with a standard deviation of only 0.2% over the full 5.7m 2 module. The relative variation is <5% in micro-crystalline silicon (μc-Si) fraction over the entire substrate ( see Fig. 3).

Aside from implementing equipment/process improvements and using larger substrates, Applied has been leveraging scale at the factory level. Pinto told attendees that the company has customers committed to gigawatt thin-film module factories. The GW-scale factory, sitting on 111 acres, will consume 500 tons of glass/day and produce 6000 modules/day — enough, Pinto noted, to cover 7.5 football fields, and the equivalent of 450,000 300mm wafers/day. Applied believes it will achieve at least a 20% reduction in the process cost with the same technology and equipment being used in the gigawatt factory configuration. The savings will come from the economies of scale in terms of reuse of infrastructure, labor, better loading of equipment, and better materials costs. “So when you’re in the inflection zone, 20% can make a big difference in the cost,” he noted.

Applied has also been taking on the cost challenges in wafer-based PV technology. The tactics being used on the manufacturing side are improving material efficiency by using ultra-thin wafers along with high throughputs (>1000 wph) and higher equipment uptimes. However, because thinner wafers have higher breakage rates on older technology systems, Applied has introduced better wafer handling techniques to reduce the breakage and also improved the process of getting a tool up and running more quickly. “If you do both of these, you can drive the uptime into the high 90s where it needs to be for an efficient factory,” said Pinto.

Another technique Applied has added to make crystalline lines more cost-effective is better uniformity and wafer binning. “If you can tighten up that distribution near the high end, the factory, by definition, gets more watts out,” explained Pinto. “You reduce the overall cost/watt.” And once the solar cell has been manufactured, it is critical that cells are tested and matched as closely as possible (they are connected in series), i.e., wafer binning, to “make the most of the lots you get.” [ Ed. note: Earlier this year Applied acquired Italian firm Baccini, a supplier of automated metallization and test systems for manufacturing
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Figure 3. SunFab tandem junction on 5.7m2 modules. (Source: Applied Materials)
crystalline silicon PV cells.


Examples of high-efficiency commercial silicon PV cells include SunPower’s all back contact cell that has achieved a 23.4% efficiency, and Sanyo’s HIT cell, which has achieved an efficiency of 22.3% (see Fig. 4).

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Figure 4. High-efficiency commercial silicon PV cells. (Source: Applied Materials

This story was originally published by Solid State Technology.


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