PV Racking and Tracking Systems of Today

From HeatSpring.com PV Boot Camp Discussion Board

Q:

I read once that the base structure of PV panel is also one of the important system to improve efficiency. Could you please explain that how a system will improve efficiency due to base structure?. Also there are some base structures which are controlled by a motor (with a micro controller system) to focus sun automatically to increase the efficiency. If so, Is there any optimal design for base structure?

A:

In the industry we call it a racking system and if the system allows for better airflow, that will increase the cooling, which will increase the voltage, power, energy and income from the system. This increase is not huge, but it is noticeable and often a few percent increase depending on the amount of cooling.

Trackers are racking systems that will have the PV face the sun as the sun moves through the sky. When PV was 10x more expensive 10 years ago, tracking systems made more sense, because we were able to extract 20 or 30% more energy with the tracking system. Now with PV so much less expensive, it often makes more sense to buy extra PV instead of an expensive tracking system, which moves 365 days per year, flexes cables, is effected by wind and has many moving parts that require replacement and maintenance. Often if you see a tracker today, it will be a broken tracker. One of the great things about PV is that is often has no moving parts and requires very little maintenance. Trackers add big maintenance costs over the lifetime of the system.

All of that being said, the main kind of tracker that we see today is a horizontal single axis tracker. These trackers can support hundreds of kW of PV with a single motor. The will face the sun in the east in the morning, go flat at solar noon and face the west in the afternoon. The maintenance and space required per MW are better for these kind of trackers.

Concentrating PV requires a 2-axis tracker, but concentrating PV is extremely rare. It is just a better investment to use the mass produced products that we use today, which are mostly 60 and 72 cell PV modules that are about 1m wide and 1.7m or 2m in length.

In this fast growing industry, there are many exciting ideas and  when you look back 5 or 10 years, most of the exciting ideas have gone bankrupt. This is much as it was in the computer industry in the 1990s. Most of the companies went bankrupt, but still computers turned out to be the future. Wish I had a time machine and could tell myself which companies made it!

With PV, what is the standard for PV systems today that banks will invest in is the standard system, usually with no tracker, but sometimes on large ground mounted systems a horizontal axis tracker. For buildings trackers are very unusual.

Thanks,

Sean White

From HeatSpring.com PV Boot Camp Discussion Board