Photovoltaics Comes of Age

Solar panels are cheap enough to become a major component of green energy.
Originally posted at: MIT Technology Review

Zweibel-KenThe United States has supported research into photovoltaics for almost 40 years, recently with a 30 percent investment tax credit. Japan instituted incentives in the 1990s, when photovoltaics cost at least five times as much as residential electricity. In the new millennium, Germany instituted incentives an order of magnitude larger.

Thanks to these efforts, the cost of photovoltaic modules has dropped 40 percent in the last 18 months. Photovoltaic electricity now costs about 15 cents per kilowatt-hour in the best sunlight. That’s only twice the cost of wholesale electricity and wind. Costs are expected to continue decreasing, and electricity is worth more during the daytime than at night. That means this technology is finally cheap enough to become a significant element in plans to combat climate change and oil dependence.

First Solar, Ordos, China, US

China, USHow can we be so profoundly behind in our awareness of solar PV? China signs an agreement with the world’s largest PV company (which just happens to be an American company) for the world’s largest PV system (equivalent to Hoover Dam in output) using the most advanced, lowest-cost technology, and we haven’t even heard about it? The company, the technology, the concept of big PV. All that is new. Our press and our government are in the dark. Why?

We hear about self-promoting Silicon Valley PV start-ups manipulating the press for coverage while they raise money (First Solar is from the Rustbelt). We hear about Chinese silicon PV companies using low-cost labor to take the market away from everyone, because that is a cliché of our psyche – the foreign threat.

Buying PV Without Getting Ripped Off

PV pricesThe second, and much improved, version of California’s experience with PV prices, Tracking the Sun II, has been released.

It is a huge step forward from the previous report, which seemed to treat CA as an island and ignored the much greater experience of the non-CA-dreaming world outside. This year there are special sections comparing CA with Europe. We are blessed!

However, the report is still out of date, since it ends in 2008 (with an unrevealing peek at 2009). As we know, prices for silicon modules have dropped like a stone, and very large quantities can be bought under $1.5/W.

Now what we can do from the CA report is actually estimate what we should be paying going forward without getting ripped off. The reason this is important is that most people will read the CA report without the knowledge of the staggering plunge in module prices and think we are still stuck at $8/W for residential systems (and similarly high prices for the commercial and big ground-mounted systems).

Solar PV Getting Cheaper, But Press Doesn’t Have a Clue about the Real Story

Solar PVRead this article by the AP and you would think the reason solar is cheaper is subsidies.

Well, good sources tell us that Chinese crystalline silicon modules are available at $1.4/W; and big systems can be installed with trackers at $3/W (which means $2.5/W without them). These prices put solar in the 10 c/kWh range right now in good sunlight!

The mainstream press probably doesn’t know what these numbers mean. For comparison, modules used to sell for $2-$4/W, so $1.40/W is a huge drop. And big systems went in for $4/W or more, and little ones on rooftops for the outrageously high number of $8/W quoted by the article and out-of-date reports.

Fast Cloud Transients

One of the thorniest issues that seemed to be facing large, utility-scale PV systems was sudden changes in PV system output due to the movement of single clouds on an otherwise sunny day. Now it seems that this issue has been resolved favorably, in an economical manner.

Figure 1 shows a particularly excruciating example of solar variability.

Figure 1. Worst case example of incident sunlight caused by the movement of transient clouds on a clear day (After Hoff and Perez)

Figure 1. Worst case example of incident sunlight caused by the movement of transient clouds on a clear day (After Hoff and Perez)

This kind of sunlight graph put chills down the spine of utility engineers and caused a major setback for the deployment of large-scale PV systems. PV output responds instantaneously to such changes. Such variability also compares unfavorably to solar thermal electric (STE) systems, which have natural thermal inertia, which damps out the sudden changes. STE system installers gladly took note and publicized the PV problem to everyone making a choice between STE and PV.

The Cost of Solar PV

The Cost of Solar PVI get brassed off of constantly seeing ultramundane high prices for solar PV charged as the only possible price. You read this in articles from all sorts of media, and it is gulped by the slump and sinker. So how much does PV cost?

The response is “prices.” There is no real price, because there are many prices. Price differs by the local sunlight amount and by the system’s size and type.

And two types of prices exist– dollars per watt, which is price per momentary output. And cents per kWh, which is price per unit of energy imparted. Dollars per watt is difficult; cents per kWh is harder.

So with this in mind, let’s do some prices!

Great systems are cheaper than little systems; pocket-sized systems, like those on your house, are more expensive again. If we admit the greatest systems can be inducted (sans delays and all sorts of undefinable costs) at $3/W; then large rooftop systems on WalMart might increase the price for $4/W; and inhabited systems for $5/W. These would be “entire” systems, with no withholdings and other arrests. For more characteristic ones, you can supplement a dollar or even $2/W. These are all stationary mounts; if you wish tracing, supplement another 50 ¢/W to a dollar to the great system price (but you get 25% more output).