System not selling enough power

 I have 24 Kyocera 120watt panels rigged in groups of 4 to create a 48
volt system. Often during peak hours my SW4048 is selling about 600
watts, even under no other AC load.  (I have batteries too,
disconnecting them changes nothing.)

I disconnected and measured each group of four panels from positive to
ground. Each group was delivering 7 amps.  So that is 48 volts * 7
amps * 6 groups which equals 2016 watts.

2016 / 120 volts = 16.8 AC amps

However, all I ever see on the inverter AC Amp meter is about -5 (600
watts).

I have a C40 charge controller regulating the panels, but I've also at
times bypassed it to make sure it wasn't doing something odd.

Does anyone have any ideas what is going on?

Thanks,

brian

  On 31 Aug 2003 13:25:59 -0700, brian@worldcontrol.com (Brian Litzinger)
wrote:


It's may be a programming issue.

What is the setting of your Max Sell Amps AC?  The default is 30 for a 48V
system, but maybe yours got changed?



-- ron  (off the grid in Downeast Maine)

 
It was set to 30. I also reset the unit and reprogrammed it a few times.

I'm thinking of adding amp and volt meters per panel group.

I've notice that loose connections can cause havoc, so I'm check all the
interconnects.

Could someone with batteries post their settings for the SW4048 and
C40.  I suspect the settings in menus 17 & 9, along with the C40 settings
should make a fair comparison.  Though to be honest I don't expect the
problems to appear in the settings.

It could well be that everything works fine and it is just my way of looking
at things, and the fact that my Fluke meter's AMP capability is only
10 amps.

 
That's not how you measure the output.
Short circuit current is significantly higher than current at rated
voltage, and open circuit voltage is significantly higher than at
rated current.

You can't multiply the open circuit voltage and short-circuit current
and come up with a number that means anything.
You need to measure the current in circuit, and the voltage to get an
accurate idea of the wattage they are delivering.

--
http://inquisitor.i.am/     |  mailto:inquisitor@i.am |             Ian Stirling.
---------------------------+-------------------------+--------------------------
To do is to be
To be is to do
Do be do be do do

 On Mon, 1 Sep 2003 00:14:34 +0000 (UTC), Ian Stirling


On those Kyocera panels, the current at max power should be 7.1 amps, and
the voltage at max power should be 16.9V.  Open circuit voltage is 21.5V
and short circuit current is 7.45A.

I agree that measuring the open circuit current and multiplying that by the
nominal voltage (48V) is not an accurate way of determining output, but the
7A isn't far off from what it should be, especially given that we don't
know more about the nature of the measurement.

He should be selling more than 5A at 120V unless the SW4048 is not properly
programmed or the power is going someplace else.  It's certainly possible
that the cells or something else is defective, but I'd check the simpler
stuff first.  Then we can see if he's got the equipment to properly measure
the power coming out of the PV cells.


-- ron  (off the grid in Downeast Maine)