Wattsun Tracker grounding change to prevent lightning damages.
August 2012. Now that I have spent hundreds on new power supplies and circuit boards to keep our wattsun trackers up and running, I think it is time to fix the problem. The problem is the circuit boards are grounded through to the array frame grounding points thereby breaking the grounding rule to never have more than one ground point within any inverter DC system, giving rise to induced high voltage through the two bonded grounding points from any lightning ground strike within a mile or more of our system. As long as the lightning strike is at right angles to a line through the two grounds, no induced static voltage is a problem. But align the lightning strike within that bisect line between the two grounding points and BOOM! You have induced voltage through the grounding bond! First let me repeat the grounding rule I build and design by; http://www.wholesalesolar.com/pdf.folder/Download%20folder/lightning%26grounding.pdf
The first image is front and back of the control circuit board out of my Wattsun 125 single axis tracker. Yes, I have needed to replace four, (4), circuit boards in five years, and three 24 VDC power supplies, all with a retail price of nearly $200 each. The second image is the reason; both of these mounting bolts bond to the grounding of the tracker array frame, which is completely different and not bonded to the main system PE and ground point, except through the circuit board alone. The name for this in DC systems is "GROUND FAULT". This gives rise to huge voltage surges through the circuit board from lightning-earth strikes. Surges not protected by the 5 amp fuse, which compounding the problem, protects from amperage not necessarily voltage, and is on the hot side of the DC supply not the ground or neutral side.
To fix this properly; 1.) we need to isolate the electronics box from the array frame ground, and 2.) ground the electronics and box by connecting a bond directly to the main system PE. This fix brings us back to code grounding of an inverter equipped AC/DC system.
Here is the tracker electronic box that is bonded to the tracker frame grounding system. We will change the stainless steel mounting plate to white plastic. The electronics box isolated from the frame with a new PE connected to the box, upper right corner mount bolt. And we tied the new PE into the main system PE, at the power supply. We also changed the main 120VAC fuse to the power supply from a 5 amp as per Array Technology directions to a 2 amp fuse. Note the max input on the power supply,(1.8A).
UPDATE 11/20/2012!! This change did not work!! The very next lightning storm blew out both of my WATTSUN 125 single axis TRACKERS electronics! Most likely because we forgot to isolate the light sensors. NOW WE HAVE A SOLUTION! Throw out all the Wattsun electronics! Even the sensor and replace with a kit from WINDY NATION. http://www.windynation.com/products/solar/solar-trackers/suntura-single-axis-solar-tracker-hd
We installed this kit using the E-W controller connected to the Wattsun drive and added the kit's 24 inch actuator to our Wattsun tracker's Zenith to end up with a DUAL AXIS TRACKER! WORKS GREAT! And runs off of the 24 VDC power supply. We added a duplex outlet and standard plug into our power supply so we can pull the plug during severe lightning storms, and now we can manually move the array vertical for hail or snow, and horizontal for wind events. We added a waterproof toggle switch next to the new SUNTURA controller so we can manually move the array and turn off power to the controller to keep the array where we want it until the weather event has passed.
Our Wattsun 125 tracker no longer has original sensors and controls. Now a dual axis tracker, thanks to Windy Nation's Suntura control. We purchased a single axis kit and used the E/W to move the original Wattsun slue drive and used the kit's 24" actuator to drive the N/S, or Zenith axis.
The Wattsun electronics box is now the J-box for our Suntura tracker, and sports a toggle switch to turn off all power to the new control after we manually move the array into position for severe weather, so the array stays right where we want it.
We added a 120 VAC plug, to easily pull AC power for the DC power supply if severe lightning is imminent, to prevent destruction of the 24 VDC power supply. In the past we have lost three units to lightning. We think it was due to the Wattsun electronics' sensor and circuit board grounding. Now we can be double sure to survive extreme weather. As a benefit we now have 120 VAC outlet for our solar powered electric string trimmer. By the way, we use a Newton electric lawn mower also. Our mowing is solar powered as much as possible. FYI, the neutral and equipment PE wiring meet code requirements for an outlet at this placement. An in line fuse is within the outlet box.
Both trackers now retrofitted with SUNTURA control and dual axis POWER!
Notice the shadow of the panels frames from the SUN. It is nicely lined up and tracking perfectly for Sunlight to go between the frames.
December 18, 2012. Now the Wattsun tracker's slue drive limit switch cam on tracker '1', came loose and allowed the tracker to move freely through till it bottomed out on the frame members. I don't know how the Suntrua control kept from blowing up! It's another testament to Suntura's heavy duty design! I finally figured out how to tighten up the problem. Need to keep my eye out for this Wattsun problem in the future.
February 5, 2013. Last December tracker 1 had the issue I wrote about above...Today I found tracker 2 locked up full rotation to the East. A stock Wattsun limit switch quit functioning, rather than the cam loosening as last time. The motor was hot to the touch and the electronics in our Suntura controller are fried and non functioning. This is a $300 repair on top of a long list of repairs costing over a grand for both trackers in five years. I have not decided what to do about it other than I moved the tracker back to solar South and can still operate the Zenith manually. The Zenith automatic control also failed but at least the manual part of the controller for Zenith works. Manual control of Azimuth no longer functions. Had to hotwire the motor directly to move the array back to solar South. Is anyone familiar with the concepts of Enthalpy and Entropy? This may apply here in a way as to future designs.
March 6, 2013. Tracker 2 works perfectly after replacing two $0.49 diodes inside the limit switch on Azimuth drive. Both trackers now operating perfectly.
Update 6/10/2013, One tracker wants to move east no matter rain or shine, night or day. I'd call it a significant bug. Nothing out of the ordinary caused it that I saw. After finishing up the testing for skewed arrays I turned off both trackers. No immediate plans to repair any time soon. When I do I am thinking of throwing out the Suntura controller and installing only manual switches for tracking to control the arrays for more testing and the like. My first impression may be to use the Suntura control to actuate very light amp relay switches which in turn operate the actuators, even though Suntura is suppose to handle up to 10 amps 24 VDC motor loads. Just a guess to try.
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