After a lengthy discussion with a friend of mine, I have decided to post some tips regarding dual axis trackers for those of you wanting to implement them in your home solar PV systems. I won’t say I laughed much during the discussion, but you will get the idea of the conversation about his experiences as a solar installer in Florida.

The following are just some basic tips to consider when thinking about using a tracked system. Preferably before you buy the equipment.

Use Proper Shading and Spacing

Static solar arrays are relatively simple to site properly. They need a solid frame, a small space in-between and a couple of inches underneath for airflow. They need an unobstructed view of the sun for as much of the day as possible. Using dual axis trackers adds to that requirement.

As they move during the day, the tracked array will be somewhere near vertical at dawn and dusk. Whatever is behind the array will find itself in the shade for quite a while. If you’re using two arrays, make sure one does not shade the other. Or that the array doesn’t put anything else into the shade, like your house for example.

Use a Solid Foundation

A dual axis tracker can provide a decent power increase when used correctly. However it generally costs more to implement than a static array. Trying to claw back some of that expense by using less, or inferior concrete is definitely the way not to do it.

On a pole mounted array, there is a lot of weight, and a lot of gravity on a very narrow point. A pole mounted array is a giant windbreak and will catch every gust that comes your way. It needs to be anchored very securely.

Otherwise the concrete will crack under the stress and the whole lot can come crashing down. If anything, over-specify the foundation. More concrete, good concrete, is ideal here.

Check the Utility Limits When Grid-Tied

The ability to sell excess power to your local power company is a very useful idea. It’s something that the Europeans have been doing for years, and it seems to be slowly catching on over here. Not every power company has such arrangements, so it’s worth checking before spending extra on an array to purely sell back excess power.

Of those power companies that do buy power, it’s best to check their terms to ensure they are a) fair, and b) have realistic limits. It’s not always worth buying an extra couple of panels for the dual axis tracker system purely to sell.

While trying to speed up the ROI on the system is laudable, if the power company has yearly limits of how much power they will buy, you may be wasting money.

These are all common sense tips, but as I learned the other day, not everyone knows them. Hopefully, this post will save families some hard-earned money and a lot of work.

The use of trackers allows solar arrays to follow the sun as it moves across the sky during the day. It adds a little complication to an otherwise simple system but the payoff is increased efficiency. Dual axis trackers move the panel in two directions so they can follow the sun during the day and throughout the year.

The case for adding extra things to go wrong in a largely maintenance-free solar PV system is that efficiency. Firstly, it means that the power you harvest is increased by up to 15 percent, depending on the type of panels used. Dual axis trackers can theoretically increase that to 30 or 40 percent.

Secondly, it means the panels are always working, throughout the day and throughout the year. Depending on your latitude, the position of the sun during the year can vary by up to 30 degrees. While a stationary solar system can still harvest sunlight from oblique angles, it works better at steeper ones.

With the price of solar panels still being expensive, it’s important to squeeze as much out of them as possible. In large-scale solar systems, that importance becomes vital. The ability to increase efficiency by up to 40 percent when dealing in MW is attractive indeed.

The other benefit of using dual axis trackers is that you need less panels to achieve a given output. If your home needs 3.3Kw to break even, a tracker means you can achieve that with less panels than if they were static. The downside is that it’s hard work installing a tracked solar PV system on a roof.

It’s much better to use a pole mounted system if you’re going to use a tracker as it’s easier to maintain the tracker and for it to move the panels to the desired angle. It gives the panels plenty of space to move, and allows periodic maintenance without having to disassemble the panels first.

The downside is that pole mounted systems need space. They need an unobstructed view of the sun, plenty of room to move, and to be out of the way of everyone. They can be an eyesore, which limits their application in residential settings. Those who don’t have to worry about neighbors should look these kinds of systems up as they have significant advantages over roof mounted setups.

There are of course downsides, so it’s important to get a clear picture before investing in any kind of solar power system.

Dual axis trackers have really seen an uptake in commercial solar PV systems. In Europe, uptake of tracked solar systems is estimated to have increased by 22 percent. In Spain, where solar power is big business, up to 30 percent of all new solar PV systems installed since 2008 have used single or dual axis trackers. The country is currently installing PV systems with an output of around 2.5GW per year, which is a significant amount.

Dual axis trackers may seem overkill for many residential applications, but with a life of between 10 and 25 years, a solar PV system has to look into the future too. Who knows what our power demands will be in that time?

In a nation where more is good and bigger is better, it’s easy to fall into the trap of overindulgence, overspending and over-specification. Just because something has advantages over something else, doesn’t mean it’s better. I was party to an interesting discussion about dual axis trackers the other day, and it got me thinking.

One side of the discussion was expounding the virtues of following the sun year-round on two axes. The other side of the discussion said it wasn’t necessary unless you were a commercial solar power generator. What interested me was the assertion that just because it was possible to harvest more energy with a dual axis tracker, that it was better.

So in the cold light of day, let’s take a look at both systems and their pros and cons.

Dual Axis Tracker

A dual axis tracker moves a solar panel array in two planes. Side to side and up and down. That gives a full range of movement to the array and allows it to follow the sun across the sky during the day, and at different heights during the year.

The advantages are that you can maintain the optimum angle at all times, minimizing glare, and bounce. Bounce is where the angle is too shallow for the panel to absorb the light.

The disadvantages are cost and complexity. They are considerably more expensive than single axis trackers and more complicated. They need more maintenance and there is more to go wrong. They are larger, and weigh more too, which has ramification when constructing.

Single Axis Tracker

This version of solar panel tracker just moves from side to side. They can follow the sun during the day but need to be realigned four times a year. They currently constitute the majority of home and small-scale solar power setups in the country.

The advantages are they are simple, can track during the day and are relatively easy to install and maintain. They can keep the optimum angle during the day. They can also harvest around 90 percent of what a dual axis tracker can.

The disadvantages are that they need adjusting for the seasons, need maintenance and are a weak link in what is a very low maintenance solar system chain.

The case for or against using dual axis trackers isn’t clear cut. For simple home or smaller commercial systems a dual axis tracker isn’t really necessary. A good single axis version can harvest 90 percent of what it’s dual moving cousin would at considerably less cost and maintenance.

For large-scale or utility standard solar systems, a dual axis tracker can make quite a difference. That 10 percent increase in power output can mean quite a lot of wattage when you get into the high Kw range. These kinds of environments will have maintenance teams to keep the equipment working, and will be able to justify the extra expense they demand.

As always in these discussions between what component is better or worse than another, it isn’t clear cut. Each type of solar panel tracker has strengths and weaknesses and lends themselves well to different scenarios.