Hacker News Reader

Comment by mchannon | Hacker News Reader

I've been in solar energy as my primary vocation since the 1990's.

I've built solar cars, I've built solar panels, I've installed solar panels, I've designed solar trackers. I know this industry inside and out.

I'd never heard of an east-west array before (though I did experiment with one-cell-wide "crinolations" at 60 degree angles, did not find any value to using them but it was a different application where low-angle light wasn't a factor). I'd never thought of such an array on this scale, at this low angle, before.

I don't think most of the people reading this article quite understand that this is a completely different kind of array topology to flat-plate fixed-tilt, or tracking-based systems. Do yourself a favor, if you consider yourself intellectually curious, and if you came away from skimming this article thinking there's nothing new under the sun, read it again with a keener eye toward the novelty of it.

View on HN

I have an east/west array on my roof, as my house is positioned with the front facing west.

In the winter it's outperformed by a south facing array (northern hemisphere) but in the summer the east array gets a ton of sun before midday, and crucially, it's getting a ton of sun when the temperatures are a bit cooler, so it performs very well.

I actually use this exact example when encouraging careful attention to paradigms where a fundamental variable is slowly but consistently changing.

It's essentially equivalent to a boundary on a phase diagram: Cost/Watt has fallen past a critical threshold, and suddenly this dramatically different approach just makes more sense.

Another interesting configuration is vertical bifacial panels aligned on North-South axis and interspersed with farming rows. Low-cost panels make it feasible and it doesn't much block agricultural production if the panel rows are spaced far enough apart.

I guess trackers really are an American thing? I’m in solar for ten years in The Netherlands, and I don’t think any utility scale fields use tracking. For residential roofs east-west placed systems have been an option for the same amount of time. They are now gaining popularity in The Netherlands because of net congestion during midday.

Trackers are useless when the majority of the incoming sunlight is diffuse (as is the case where you live).

Trackers are useful when the majority of the incoming sunlight is direct (America has a mix but the western half and parts of the south have a lot of direct).

Trackers are essential when you use concentrated sunlight.

A tracker that doubles the amount of sunlight hitting a panel is not free, but it also makes the panel take up 2x the area, or more, to avoid shading its neighbor.

The thing people tend to forget about trackers is they offer this trade-off where you can trade shaded area for power per rated panel. When land is cheap and panels (or arrays, heliostats, power towers, etc.) are expensive, trackers make sense.

The reverse has been the case for the past ten years, and continues to get more true by the day. I doubt we will ever see the day return where land is cheap again and/or PV are expensive again.

Thank you, I went back and re-read after seeing you comment and I did indeed miss the big point here. I had been concerned that even if PV costs reach near zero, the fixed install costs would still limit future reductions on solar costs. Clearly not!

Reply on news.ycombinator.com