The 0.1 volt reading is meaningful as a voltage measurement.

When you set your DVM to an ohms range the meter uses its internal
battery to apply a small voltage to what it assumes to be a completely
passive component.  From the resulting current and voltage values it
calculates and displays the resistance ( R = V/I ).  If the component
being tested produces voltage on its own, the meter displays misleading
results, perhaps even negative (!) resistance, assuming it isn't
damaged.

Connecting an ohmmeter to a semiconductor p-n junction like a diode can
tell you which end is which, if the meter uses a high enough voltage to
overcome the voltage drop across the junction ( about 0.65 v for
silicon).  The reading in the conducting direction still should not be
interpreted as resistance in the traditional sense of the word.  A
silicon solar cell has some resemblance to a silicon diode with the
added complication of being a voltage source.

Larry A.

Ben McCafferty wrote:
>
> I followed the instruction from Jim to cover the panel so it would not be
> producing any current, and the voltage output was 0.1.  Would the reading
> still be useful?
> tx,
> bmc  :)
> Ben McCafferty
> ben@volkscafe.com
>
> Volks Cafe
> 1823 Soquel Avenue
> Santa Cruz, CA  95062
> 831-426-1244
> http://www.volkscafe.com
>
> > From: Larry Alofs <lalofs@ENTERACT.COM>
> > Reply-To: Larry Alofs <lalofs@ENTERACT.COM>
> > Date: Fri, 3 Jan 2003 11:43:38 -0600
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Solar panel wrap-up
> >
> > The readings will not be meaningful when you connect an ohmmeter to a
> > component which is producing voltage and current.
> >
> > Larry A.
> >
> >
> > Bill N wrote:
> >>
> >> Minus resistance?  Is that like negative pressure?
> >>
> >> Bill
> >>
> >> ----- Original Message -----
> >> From: "Ben McCafferty" <ben@VOLKSCAFE.COM>
> >>>
> >>> As an aside, I did put an ohm-meter on a panel this morning, and the
> >>> responses regarding diodes seem to be dead on.  The resistance one direction
> >>> was about 19 MOhms, and the other direction was about -4 MOhms.  So I doubt
> >>> we'll be seeing any glowing solar panels in the campground at night.