Inquiring Minds Want to Know!
Over the weekend we really went to extremes to show just how tough solar panels can be. Today we’ll tell you the results.
We started with a Suntech STP280 that had been hit by a tractor. The frame was bent, wires were ripped loose, glass was shattered and many of the internal cells were broken. Short circuit current of a shiny new panel should be around 8 amps. Open circuit voltage should be 44V. In the “as found” condition, we had 4.5 amps and 43 volts. Connected to a load we could get about 68 watts. Not bad for a module someone had thrown away.
Especially for a panel that looked like this.
And to recap what happened next:
After the shooting, I measured output under varying conditions. The hole sure was a handy place to put a voltmeter!
And the open circuit voltage was….39V.
Next I added a 24V driving light as a load. The lamp pulled .961 amps at 24V or 23 watts. That’s all the lamp needed. Was there more?
Next, I added a 12V battery, to be charged, and an ammeter.
Now we have 2.508 Amps at 13.8 Volts for 34 watts.
How about 2 batteries in series and the light? 26.2 Volts X .880 Amps = 23 watts
Here’s a look behind the scenes…no trickery, just honest destruction.
Conclusions? Obviously, PV modules work better if you don’t smash them with a tractor, shoot them with a pistol and shoot them again with a shotgun. The worst damage appears to have been done by the tractor. That hit took it down from 280 watts (rated) to 68 watts. The first two shots, from a .45 and a 12ga. slug, had no effect on the output. It was the huge hole from the shotgun when I backed up that cut the output in half. The point is that the panel continues to output usable power and it did a good job of topping up those batteries.Oh, and remember “Don’t Try This At Home.”By: Neal Collier