Photovoltaics and Our Energy Future

In a previous post we provided an overview of solar energy and promised to delve into more detail about specific technologies in future posts.  Here, we’ll look into photovoltaic (PV) technology and its potential as a cost-effective way to harness renewable energy.

The International Space Station. Source: PBS-NOVA

The International Space Station. Source: PBS-NOVA

As a bit of review, PV panels comprise multiple cells made from specific semiconductors whose electrons become excited by contact with light. The resulting energy is in the form of an electric current, allowing us to convert sunlight directly into electricity. This technology was first patented in 1946, and entered the public view in a big way in 1958 with the launch of the Vanguard 1 satellite, the first to be powered by photovoltaics. Today, the iconic image of the International Space Station soaking up the sun represents one sector for which PV has proven revolutionary.

But many earthly uses exist, as well, and in 2011 PV accounted for 67 gigawatts (GW) of global electricity generating capacity, compared to only 1.5 GW in 2000 (that’s an increase of over 4,300%). Still, this only meets a tiny portion of electricity demand – in the US, PV generation has grown rapidly, and its capacity stood at 3.5 GW in 2011, but this only made up about 0.03% of total generation. Even at these growth rates, PV will remain a relatively small contributor for some time.

And yet, we continue to hear about PV and its potential to provide renewable energy. In fact, solar panels have become a symbol of environmental friendliness, the emblem of sustainable energy. Given its small contribution to energy production, PV’s popularity may seem out of place, or at least premature. While those who have visions of a PV-powered world may aspire to an unrealistic dream, however, the technology’s significance – and its potential – should not be overlooked. For starters, the cost (historically, the biggest barrier to its widespread adoption) has come down significantly over the past few years. The average price of installed modules has plummeted by 50% since 2008 alone. At this pace, PV is quickly approaching grid parity, the point at which electricity from PV is equal to the average cost of electricity from the grid. Grid parity is widely viewed as a critical turning point for the competitiveness of PV – so much so, that the Department of Energy launched the SunShot Initiative, which aims to help achieve this goal by 2020. Many experts predict explosive growth as we approach and then surpass grid parity, and the Department of Energy expects this to allow PV’s contribution to national electricity generation to grow to 11% by 2030.

NREL's map of PV potential in the US.

NREL’s map of PV potential in the US.

Like most renewable energy technologies, PV offers different opportunities in different regions. While it may never be the world’s predominant energy technology, PV can provide a large portion of electricity in certain areas. As we mentioned in our earlier post about solar energy, the amount of electricity produced by photovoltaic cells depends on the amount of available sunlight, but they actually operate less efficiently at extreme temperatures. As you can see on the map above, the Southwest is the US region that receives the greatest intensity of solar energy. Temperatures in that part of the country, however, generally exceed the optimal operating temperature for most PV panels – in the Southwest, a technology called Concentrating Solar Power actually tends to be the best bet for large-scale solar energy development. Although the sun is a bit less intense in Miami than in Albuquerque, PV panels will have a longer operating life in Florida (due to milder temperatures), and will ultimately generate more electricity as a result. That’s not to say that PV can’t harness large amounts of renewable energy in places like New Mexico and Southern California (it already does). It’s just to demonstrate that, while the Southwest and Southeast are both hot, sunny places, from the standpoint of solar energy potential, they have important differences. But all across the country, PV offers opportunities for residential or commercial on-site renewable energy generation, often reducing reliance on the grid. This allows homeowners or companies to generate their own electricity when the sun is shining, something that deserves our renewed attention in the aftermath of Hurricane Sandy.

The Verdict: PV is a promising technology that stands to play an increasingly prominent role as we move toward greater reliance on renewable energy. With prices coming down and efficiency improving every year, PV is becoming more attractive to homeowners, investors and utilities. This renewable energy option has been growing at breakneck speed and all signs point to even faster growth ahead. While it may never power the world, PV can certainly be a significant contributor to our energy future.


4 responses to “Photovoltaics and Our Energy Future

  1. I think these are some good points when talking about PV and the opportunities ahead. One thing I’d like to see more on is the challenge of distributed generation. PV shines best (no pun intended) in areas where remote power is needed. The delivered cost of fuel for generators can be really high and PV fits the need for this niche really well. However, the tables are stacked against it when grid operators have to deal with distributed generation from homes and commercial scale projects. What do you think? Is this a technical challenge or a break in the mold of how utilities need to think operate and design their systems going forward?

    • John:
      Great points – you’re right on the money about PV’s fit for remote power generation. Some would say this is its true calling (can you think of power needs more remote than those aboard the ISS?). In my view, the challenges you allude to are multifaceted. Technological improvements and cost reductions would allow us to bring in solar- or wind-generated electricity more efficiently and over greater distances, for example, but at the moment it’s not in the utilities’ interests to usher in that change. Storage issues come to mind, too. Like you suggested, taking full advantage of PV’s potential will require not only technical innovation but structural innovation on behalf of the utilities. While the fundamental changes we need for effective, widespread distributed generation may be difficult for utilities to accept, It may behoove them to take the lead rather than allow the independent development of a system that may ultimately make them irrelevant (albeit, not any time soon).

      Interestingly, this op-ed ( from yesterday’s New York Times discusses the resilience that grid-connected PV can provide in densely populated areas, as well.

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