Voltage on one lead of solar panel

ttpvt1 · 10-30-18, 08:18 AM

Can someone explain what the voltage on one lead (+ or -) of a solar panel is?
Obviously testing voltage from one lead to the other is Voc.
From experience, testing voltage from one lead to ground shows a small initial voltage which quickly dissipates to 0. Does this mean that touching the bare conductor from one lead of a panel (or string) presents no shock hazard?

philb · 10-30-18, 06:26 PM

You should not get any voltage on a solar panel from only touching one lead (+ or -) to ground unless it's grounded somewhere. I do check this because I don't want there to be any voltage. If there is, I could get electrocuted when I have to work on my panels.

Some charge controller companies tell you specifically not to ground the panels. NEC also has exclusions for not grounding the negative lead but does ground the panel frames.

"From experience, testing voltage from one lead to ground shows a small initial voltage which quickly dissipates to 0. " This could be due to a small amount of static electricity or the VOM self calibrating.

jeff5may · 11-02-18, 11:45 PM

The momentary reading is indeed static electric charge. In every electric circuit, there exists a small amount of capacitance between the live circuit and everything else. When you probe the circuit, the measurement will not stabilize until the capacitance is discharged. A more sensitive (high impedance) instrument will take longer than a less sensitive instrument to drain the charge.

10-30-18, 08:18 AM	#1
ttpvt1 Lurking Renovator Join Date: Oct 2018 Location: Wisconsin Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	Voltage on one lead of solar panel Can someone explain what the voltage on one lead (+ or -) of a solar panel is? Obviously testing voltage from one lead to the other is Voc. From experience, testing voltage from one lead to ground shows a small initial voltage which quickly dissipates to 0. Does this mean that touching the bare conductor from one lead of a panel (or string) presents no shock hazard?

10-30-18, 06:26 PM	#2
philb Apprentice EcoRenovator Join Date: Nov 2010 Location: Oklahoma City Posts: 155 Thanks: 58 Thanked 17 Times in 14 Posts	You should not get any voltage on a solar panel from only touching one lead (+ or -) to ground unless it's grounded somewhere. I do check this because I don't want there to be any voltage. If there is, I could get electrocuted when I have to work on my panels. Some charge controller companies tell you specifically not to ground the panels. NEC also has exclusions for not grounding the negative lead but does ground the panel frames. "From experience, testing voltage from one lead to ground shows a small initial voltage which quickly dissipates to 0. " This could be due to a small amount of static electricity or the VOM self calibrating. Last edited by philb; 10-30-18 at 06:59 PM..

11-02-18, 11:45 PM	#3
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	The momentary reading is indeed static electric charge. In every electric circuit, there exists a small amount of capacitance between the live circuit and everything else. When you probe the circuit, the measurement will not stabilize until the capacitance is discharged. A more sensitive (high impedance) instrument will take longer than a less sensitive instrument to drain the charge.