[pvusers] Mounting PVs on camper

[Bill Neill <solarbill2002@yahoo.com>]

I have written to this list about RFI issues. Here is some more info.

All five pvs are mounted in aluminum welded frames that are bolted to
the aluminum metal fabric of the camper. The layout is 2 pvs front, 1
pv sideways, and 2 pvs rear. All mountings are flat except the 1 which
is at 20 degrees up, South facing. Here is the layout on the camper
roof:
-   -
  |    ->South
-   -
I have no way of tracking the sun and would ask if you all have a feel
for just how much of an advantage I am missing during October 15 to
April 15th (during winter months) without tracking.

Notice that all five pvs are electrically grounded to the aluminum
fabric of the camper. That is the frame of the pv is aluminum, but the
electrical box and connections to the pv are in the upper center of the
back of the pv. I suspect the negative side is in-fact in common with
the frame of the truck, because the control panel has a charge circuit
for the truck battery that I do have connected and so ground is
provided through the truck negative side.

Is it true that no electrical connection exists between the frame of
the pv and the pv negative connection on the back?

I called the factory and they told me not to use the diode in series
with each pv as it is not required - so I am not using these diodes. Is
this good or bad?

My max charge current is 22 Amps (tip top of the bell charge curve)
lasting only about 30 minutes, then starting down.

I have some experience with golf cart batteries and know that the 36
volt or 48 volt units all have 25 Amp range meters on the chargers. It
is typical for current to be at about 20 Amps for the first hour or so
and then reducing and finally staying around 10 Amps for several hours
and finally kicking off at 3 to 5 Amps as a fully charged battery pack.

Thus my observation is that I have 3 series strings of 2 6 volt
batteries making a 12 volt system at 3 times the current. Thus,
applying the knowledge about golf cart charging, 60 Amps is needed for
about 1 hour or so and dwindling down from there to 5 or so. Clearly I
never make enough charge to get this battery pack fully charged in a
day sun cycle in the summer and not even close in the overcast winter.

Is this close to what you all have experienced and thus the need for a
gas generator or line power is required in the winter months.

Bill



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