Installing Solar Since 1983
License Number 773985


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We were hired to repair a single axis tracking system on a 400kW industrial grid-tied PV system. We were able to do so and below is some information about that system and what we learned.

Satellite view. The facility has two tracking systems, both broken when we were hired.

An electric motor dries a screw-jack that drives a linkage that moves 10 rows of panels in unison.

The linkage.

Rows of panels.

Control box for one of the motors as we found it. A few hands had been in this trying to make it work.

This is the PLC that had been controlling the tracking. There were empty relay sockets and most of the leads were disconnected and hanging.

We repaired the wiring at the motor controllers. We designed, built and installed a control assembly. The logic is handled with a Control-By-Web X401-E logic module.

Time Lapse 1

Very first time lapse after we got the system tracking. We installed an IP camera to monitor the system remotely. The video is a little crude but the clouds are pretty.

Time Lapse 2

First clean time-lapse after initial repair. With the tracker moving we logged about a 30% increase in production. The models predicted 34-37% so we new we had more work to do fine tuning.

Optimization: Once we got the tracker working again we needed to fine tune the timing and duration of each tracking movement. We realized we were losing some morning production. The control module we were using has some limitations but we were able to reprogram the unit to gain the morning production.

Time Lapse 5

Here is our first attempt to recapture the morning production. We are now at 34% gain over the non-tracking production. We think there is a bit more production to wring out if we can eliminate the inter-row shading between 7:30 and 8:30 AM.

If you look closely you can see a stripe of sunlight on the ground exposed by the north-south gap between rows of panels. If you can see this stripe you know the panels are aimed correctly towards the sun.

We invented this little "sun-dial" indicator. When the panels are facing the right direction the sun casts a shadow perpendicular to the face of the panels. The surface is translucent delrin and the shadow can be seen from either side.

Time Lapse 2021-05-06 MOV file