Manufacturer Perspectives on Array Tracking Markets, Equipment and Innovation: Page 2 of 7
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Another big innovation in version 3 is its torsion release system. When the wind blows, the outer rows of an array field receive more pressure than the internal rows. Typically, at about a 60-mph wind, the tracker row will move into a less torsioned position. Usually that means it will get more vertical, which is counterintuitive. But what it really does is act as a safety valve for harmonics in the system. You have a very long row of about 300 feet and 90 modules. It’s flexible, and at the center there’s a kind of spring effect because you have a torque tube. Resonant harmonics and torsional galloping can occur. When you have the safety valve in there, it relieves the harmonics and actually minimizes the torsion in the torque tube, which allows you to have larger spans and fewer foundations. Our new design links almost a megawatt—about two football fields of arrays—with one motor. From a maintenance standpoint, we use a very high-quality German industrial-grade motor that should last the life of the PV modules.
When you look at the tracker space today, there’s push-pull, which is a heavily weighted rigid system requiring level terrain and often a lot of earthwork. An independent row tracker is flexible—you can put it wherever a row can fit properly. We like to think of our solution as the best of both worlds because it has one motor that drives 30 plus rows, and it follows terrain. It’s flexible and yet efficient, and it minimizes failure points and components.
JS: There was a time when module prices were falling so rapidly that one possibility was a negative impact on the tracker market. What actually happened was the exact opposite.
RC: When people tell me that modules are going to get so cheap, we’re not going to put them on a tracker, I say that’s absolutely the wrong conclusion, because modules get cheap through efficiency increases. The price of a module today is pretty close to the cost of its components’ processing. It costs the same to track a module that produces 300 W as it does to track a module that produces 370 W. As that module gets more efficient, the cost to track per watt goes down. The other piece is that as we get smarter about tracking, we get more material efficient and better at manufacturing, which also drives the price of tracking down.
Then there’s economics. You spend 7%–10% more for a tracker on a project, but you gain maybe 20% in generation. That alone is a big economic gain. The more PV we put on the grid, the more we want to flatten the output from this array. With a tracker, you broaden the production profile early in the morning and later in the day, when peak power is at a premium. If you look at coupling tracking with storage, trackers allow you to use less storage because they push that power out later in the day. You get an overall economic benefit in terms of production versus cost, and you get the power in a more level fashion that’s in tune with when the utility wants it. In addition, it drives down storage capacity requirements. The economics of tracking are favorable, and the market has borne that out. Over 70% of utility power plants in the US are on trackers.
Internationally the scene is interesting. Different markets have different maturity levels, but we’re seeing quick adoption of trackers, and some markets just start with trackers. We’re doing a lot of business in Australia these days. Obviously it’s geographically dependent. If you’re up in the Northeast, maybe the gain doesn’t justify the cost, so you may go with fixed. We’re doing tons of business in the Southeast. It doesn’t have to be blazing sun; it just has to be decent for the economics to pencil out.
JS: Did you ever imagine the solar industry would grow and evolve this quickly?
RC: I always believed in solar. I had an idealistic mind about it early on, but it just seemed like the right approach. One thing I realized over all these years is that the real driver is always economics. I’m glad we’re at the point as an industry when we can offer an economic renewable solution to energy. That’s really the accomplishment this industry has attained in a remarkably short period of time.