300 GW/a: PV‘s bold horizon

What’s your first reaction to the 300GW/a goal?

I think it’s doable. With the current capabilities of the silicon-based industry, one could fairly easily conclude that it can be scaled another 10 times by 2025. That’s 13 years away and given the rate of growth that we’ve seen, it’s certainly conceivable.
Because I work in the research and technology end of things, I also do firmly believe that we’ll see other cell technologies emerge as being more cost effective. So what technology will be scaled will be quite different from the current industry footprint that we see today. In 13 years I do believe that silicon will be a major player, but I don’t believe that it will be the only technology. I also don’t believe that in 13 years that we’ll be building cell and module plants that will look like the ones that we see today. I don’t believe that we’ll be cutting wafers with a saw. I believe that we’ll have moved to a more efficient use of silicon and we’ll see plants that are more sophisticated.

In other technology sectors we’ve seen a considerable level of convergence, how convinced are you that we will see a diverse technological landscape for PV in a 300GW/a scenario?

PV modules are now a commodity. They’ve already emerged as a commodity now and I don’t see that changing. So I believe the market will be a reasonably vibrant space. A lot is going to happen in the next 13 years, I do believe that the market will be segmented and I think certain technologies will occupy specific segments. With the amount of PV that will be out there in 2025, there will be a reasonable amount of ground-mounted, very high efficiency concentrated photovoltaics – and you really don’t see that today.
I believe that rooftop systems, in residential, small commercial, and even large commercial rooftops, will still be mostly silicon. We will see higher efficiency cell designs, the leading edge of what we see today plus new designs as well.
I am still a believer that CdTe will be a part of the landscape in 13 years and will be competing with silicon in rooftop applications. BIPV, and PV roofing systems in particular, will be a new segment where CIGS and maybe CZTS, an “earth abundant” replacement, will also be competing with new thin silicon absorber solutions. Silicon will be a major player but I do believe there will be other PV technologies.
I also believe that by that time we’ll have multiple junction cell design on silicon that will occupy some of the space: For instance, technology not unlike the very high efficiency cells that we see today, which comprise a back side-contacted mono-junction, for example, that SunPower has designed.
I do believe that in 13 years the community will have developed and commercialized a double-junction cell with a much thinner silicon absorber. These new silicon tandem cells and the new thin absorber mono-junction cells will be manufactured using substantially different processes.
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What about organic PV, do you see a place for that?

I actually do. It’s been an interesting transformation for me since I’ve been at NREL. This technology has moved at a very remarkable pace in the last couple of years. OPV will occupy a special niche though. It will always be in applications that are different. The reliability and lifetime of OPV has improved dramatically, but in my gut I still don’t believe OPV will be competing head-to-head to with mono-junction or double-junction silicon cells. However, I do believe that the lifetimes will be long enough and the efficiencies high enough that it will be competing for BIPV applications.

What will be the technological challenges to 300GW/a?

Smart grids and storage will be the big challenge. I believe that we already know the basic things we need to move the cost of PV-generated electricity down to what the US DOE calls the SunShot goal, that’s US$0.50/W panel cost. And I do believe we know how to get there.

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Some say US$0.50/W is very close.

Agreed. I think that the first technology that will actually show manufacturing capabilities at that cost will be CdTe, because they are the closest today and the technical barriers for that technology to get there are really the lowest. CdTe has it’s own challenges in the near term, it’s panel efficiency has to come up, but many of us believe that it can.
Generally, if you look at where we’re at today and where we’ll be in five years, it’s a fairly easy leap to say that the cost will be in a good place in 15 years. But we’re not going to move this industry dramatically without dealing with the integration issues.
For PV to become a major player in the electricity landscape, even in places where you have very low retail electricity prices – as you do in many parts of the U.S., compared with the rest of the world, we’ve got to solve a number of integration issues, we’ve got to deal with the variability issues that come with all renewables.
Wind and PV are going to be the very big renewables and the utilities need – the technical community needs to show how there’s something big for the utilities in this – and personally I think a lot of progress can be made in just managing variability.
There is certainly some threshold after which you have to have storage: I personally think a well-engineered grid with all improvements that are possible, with a fairly straightforward integration technique excluding storage – I think 25 to 30% renewable penetration is possible. But I think at some point we have to have storage.
Storage does not today show the cost that is necessary to reach today’s retail electricity prices in places like the U.S., but I really do believe that the wild card in all of this – in all of the electricity markets in the world – is how we’re going to react to climate change and the price that we will put on carbon emissions.
I think that will change things. I think that will change the market for storage and I think there are a number of storage technologies that will compete, but it will be at a higher price point.
I think that PV will be able to compete in markets that have time-of-day pricing, markets that have a very good solar resource – for instance much of the U.S., Latin America, Spain and Italy fall into this. We have very high electricity prices during the peak, at a time when a PV system is at its maximum output. PV will compete head-to-head with fossil fuels in those places.
But for the rest of the world, I think we’re going to have to have storage at some point, so I can’t tell you right now that in 2025, with 300GW/a, that storage will have to be absolutely necessary. My instinct is that it will have to be in some markets and those markets will be supporting a higher price.
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Well a higher price will require a shift in some people’s attitude towards electricity; do you agree that that will have to take place?

I just believe that we’re going to have a different attitude, even among the most skeptical nations like the U.S., and this will emerge in the next five to seven years, maybe even sooner. Concerns about climate change will change the market for zero-carbon electricity solutions and nuclear is going to be swept up in that too.

In terms of carbon pricing, we’ve seen in markets like Australia that it’s been politically very controversial. How big a role will politics play in realizing a 300GW/a goal?

I am not a politician. I think that if you were to bring together any group of 10 economists, they are all going to tell you that we’re going to have to apply some sort of new market force to curb fossil fuel consumption. And whether you call it a carbon tax or some other tax, I think that this is going to happen. Earlier in my career, I worked for two oil companies, and I know a little bit about how the coal industry works. There is a lot of money at stake, these are very large industries. But ultimately the human and economic cost of climate change will be too big to ignore.
Right now, this question is being dominated by “special interests,” there are those that want to see the status quo maintained. Climate change will introduce very big issues that have huge consequences economically but also morally. I hope that there’s no reversal to what Australia has done, because I really do believe that these are important issues and carbon pricing is an important step. It’s going to be a bumpy road and in any industry of this size, which involves this amount of money, there’s going to be huge forces trying to keep the status quo maintained.
You can argue that if the issue is carbon, then carbon capture and sequestration (CC&S) is really going to have to work. Today, most people and most forecasts that I’ve seen about fossil fuel sources using CC&S say that the electricity produced will have a higher cost than electricity from a PV system, even with fairly expensive storage. So that’s why, we’re going to get to a point where countries like the U.S. will have a change of heart. I do believe that by 2025 we will have changed. I don’t see any other solution.