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.