Wednesday, October 12, 2011
Watch out for the bull when cow tipping–but a bull is nothing compared to 400 volts! The public (and ninjas) have a lot to learn about the new solar power technologies coming our way.
In this example, the ninja learns a crucial lesson about photovoltaic panels (PV panels): they can generate a lethal shock even when it is almost dark. The ninja knows that moonlight can produce a voltage on the PV panels, so he waits for the moon to go behind the clouds. What he did not count on was the reflection of the city lights from off the clouds. Even street lights can generate a high voltage in a solar panel.
So if the moon and street lights can generate a lethal voltage, why do PV panels require bright sunlight to generate electricity? The voltage on the PV panels can be high even if they are not producing power. Recall (or learn if you don’t have an electrical engineering degree) that power is voltage times current. No matter how big the voltage is, if there is no current, there is no power.
The next question is then, why did the ninja die? The answer is that it only takes a small shock at a high voltage to stop the heart. And large solar arrays can kick harder than a bull even at night.
Mark Robison, PE
