Let’s Do the Math: Why Fixed Solar Arrays Are the Most Cost-Effective

Recently, Terraform Industries published a post comparing the costs of mounting solar panels on fixed arrays vs. frames with trackers.

TL; DR: PV modules are cheap enough today that the simple fixed arrays are more cost-effective than single-axis tracked arrays.

While single-axis arrays still produce more energy than fixed ones, the labor and material costs required for their implementation are much higher. Fixed arrays come out ahead in terms of dollars per watt, offering the most cost-effective option for producing solar power.

Meanwhile, the use of dual-axis trackers, aka panels on a swivel stick, was not even included in this study due to the high initial and maintenance costs.

Now you may think, “the study is based on utility-scale solar farms. How can we apply these insights to residential off-grid solar?”

One of the top takeaways from the study is that the cost of solar panels has dropped significantly over the past decade. While rotating frames can squeeze more power out of each panel, the increased production does not offset the additional cost.

Instead, modern designs use fixed arrays and more panels to compensate for the reduced solar production. The increase in panel costs is more than offset by savings from less complicated and lower-cost frames. The installation costs for these fixed arrays are also lower because they require less skilled labor.

We have been recommending our clients to use fixed ground-mounted mechanisms to anchor their panels.

For our clients, building a fixed solar panel frame is easier and cheaper than installing a single- or dual-axis rotating one. Many people can do it themselves. Moreover, there’s virtually no maintenance required if you use our frame design blueprint — a far cry from dual-axis trackers, which often break down (e.g., a loose screw here, a rusting cable there) and stop tracking the sun as intended.

What about the loss in solar power production? That amount can be easily compensated for by adding a few hundred dollars’ worth of solar panels — less than the thousands you’d spend on a swivel stick.

Another consideration is the number of panels you can mount on a frame and the ease of expanding your solar field to meet evolving needs.

If you build a ground-mount fixed array, you can add panels easily and economically as long as you have the space (which isn’t much of an issue for most people in Caliente). Meanwhile, most dual-axis trackers can only hold around eight panels. Adding more means you need to spend thousands on another stick — and still be limited by the number of panels you can fit on it.

Finally, we must consider maintenance over the long run. It’s quite a project to climb up and clean panels on a swivel stick (OSHA will have something to say about that). Meanwhile, a loose connection means calling a technician and paying a few hundred bucks just for them to turn a screw.

Moreover, we’ve seen some trackers that have stopped tracking the sun (the strong UV here is a blessing and a curse — while advantageous for solar production, equipment just doesn’t last long!) They’re stuck, and what are the chances that they point in the right direction for optimal solar production?

How can I tell if my solar field is producing enough power?

The frame you choose is just the means to an end — maximizing watts per dollar while capturing enough solar power to meet your needs. Unfortunately, we’ve seen too many people with solar fields that aren’t producing sufficient power, causing a lot of frustration and involuntary candlelight dinners.

When we dimension solar fields, we consider the worst-case scenarios, such as a few consecutive grey days in the winter. Our data indicates that on a cloudy winter day in Caliente, solar production is around 7% of the highest yield day.

Dimensioning for these low production days means your solar field will produce more power than you can use and store on a typical sunny day — and that’s a good thing! Since solar panels are inexpensive, it’s a sound strategy to over-dimension on the production side to avoid coming up short when it counts.

Is there a simple way to tell if a solar field is producing enough?

If your battery capacity is sufficient to meet your nighttime storage needs, then we can start from there. On a typical sunny day, your batteries should be fully charged by midday. Seems like a lot of margin, doesn’t it? 

Yes, you may think you’ve spent too much money on panels on a nice day, but you won’t regret it when the grey winter days roll around. Plus, you won’t be draining your batteries excessively, which can help prolong their lifespan.

Ready to optimize your off-grid solar setup? See how our surgical and personalized approach can help you pinpoint issues without a costly, wholesale overhaul.