<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Gordon:
Henry et al,

Is there any way to get Excel to combine or average data points to reduce the data set below 32,000 points?

Gordon<HR></BLOCKQUOTE>

I was trying to use "subtotals" in Excel to do this but I didn't have something to key the summarization on. So that didn't get anywhere.

Now I'm playing with perl scripts do create summary data sets. I wrote a quick script to take 60 seconds worth of data and write out a summary (average) of the interesting values. Now I can generate a full graph for the entire day.

BTW it appears there are some padding/lead characters in front of the "whr" field.

arnold

BTW, does anyone have any secrets to neat cabling from the diag port.

There is very little clearance between the covers and the port. All the standard cables and adapters I have won't fit with the inside cover on.

I've been on a quest for premade low profile DB-9 male cable but it looks like I'm going to have to make my own if I want to put all the covers back on (without making any sheet metal changes).

arnold

Standard DB9 will fit , the Key is it will be in front of the breaker cover , I did this on one of my inverters but removed the two thumb screws on on the db9.

Making your own db9 is really easy , the only pins used are pin #2 and pin #5

Henry [img]images/smiles/icon_razz.gif[/img]

Ok, it's a bit primitive but it's so small I figure I should share the source code to the little perl script I used to reduce the data. I'm sure it can be done better and in other ways. You don't have to know perl to figure out what is doing.

I used the following link to install perl:
http://activestate.com/Products/Download/Register.plex?id=ActivePerl

I called the program convert.pl and I run it like:

convert.pl "input" "output"

It spits out a comma separated file the excel can easily load.


-------------------------------------------
$input=shift;
$output=shift;
$filler=6;
$interval=60;


open (OUT, ">$output");
open (IN, "<$input");
$count = 0;
$AC_PWR_A = 0;

while(<IN> ) {
if ($filler) {
$filler--;
next;
}

($Date, $Time, $VDC, $DC_Amps, $MPPT, $DC_PWR, $AC_PWR, $VAC, $whr, $AmbTemp, $HS_Temp,

$Freq, $Status) = split;
$count++;
$AC_PWR_S += $AC_PWR;
$DC_PWR_S += $DC_PWR;
if (!($count % $interval)) {
$AC_PWR_A = $AC_PWR_S/$interval;
$DC_PWR_A = $DC_PWR_S/$interval;
print OUT "$Date, $Time, $VDC, $DC_Amps, $MPPT, $DC_PWR_A, $AC_PWR_A, $VAC, ";
print OUT "$whr, $AmbTemp, $HS_Temp, $Freq, $Status\n";
$AC_PWR_S = 0;
$DC_PWR_S = 0;
}

}

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Solar Guppy:
Would it be OK if this is done at the new day roll over ? , the only issue I can think of is knowning when the day is really over and midnight seems like a safe bet
<HR></BLOCKQUOTE>

These wishlists sound familiar. [img]images/smiles/icon_wink.gif[/img]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Ron Schroeder:


1. the ability to select logging once every 1, 2, 3, 4, 5, or 6 seconds and possably also once per minute instead of just every second to allow for smaller files/ day. (Excel limits files to 32,000 records for graphing which is less than 12 hrs at once per second.)
<HR></BLOCKQUOTE>

One workaround I have done is to do a quick filter for power < X Then I delete those rows. This usually results in less then 32K rows left.

Also, there is a program here http://www.timnolan.com/hparticle/hparticle.htm called decimate.exe which will extract every x number of rows. For example, every fifth row.

Hi Henry et al,

On Monday, my system (48 SP75s and a ST2500 XR/GP set at 22 degrees, pointing due south in San Diego County) produced a System Best 19.82 kWh! My best result with the old ST2500 was 18.8 kWh in late April 2002.

However, I'm starting to think that my SP75 are underperforming. As I see it, DC current from the array is almost entirely proportional to insolation. I have observed, during times when the inverter is NOT power limiting and insolation is over 1000 watt per meter squared (clear day insolation chart and actual insolation measurements) that my DC current is 48 amperes (as measureed by fishbowl) when, the name plate current ratings should produce 53 amps at Max. Power Point* with 1000 watts per meter squared insolation. Important Point: This is not an issue of DC power, that falls as PV temperatures climb due to reduced voltage -- simply current that isn't strongly related to temp.

The ST2500XR/GP is working so well that the real characteristics of PV array are showing through quite clearly.

Gordon

* The MPPT as shone on fishbowl matched up very well with MPP from IR Measurements and calcuation of MPP.

Hi Gordon,

Isn't it fun , now instead of spending your time with the inverter , you now get to focus at other parts of the system [img]images/smiles/icon_biggrin.gif[/img] [img]images/smiles/icon_biggrin.gif[/img]

Your panels angle will match the sun angle about the 3rd week of april , since your fixed mounted , this will be the only time you will get STC current.

Also , get up on the roof and wash the panels once a month and spray down once a week.

If you do the wash next week , you will get a good idea of the panels ability for maximum output.

Having said all that , I'm not sure how you can make this measurement on your system (peak current) since if they really are putting out the maximum STC power , your inverter would be needing to make 2700-2800 watts , which it can't do.

For the current measurement , I would pull a string to get the STC watts below the limit of the inverter. Also , you not taking into account wire losses , the FishBowl DC amps will be net , not gross

Henry [img]images/smiles/icon_razz.gif[/img] [img]images/smiles/icon_razz.gif[/img]

Henry,

Wire losses don't produce a loss of current, only voltage -- current proportionality to insolation is where my concern is.

Since DC power is voltage x current, when the cells are hot, the loss in performance is due to the loss of voltage -- that is a lower MPP, not current falling off.
I figure it like this:
Each cell's voltage falls by 2.3 mV per degree C above their nameplate MPP rating at a cell temp. of 25 degrees C. So, if the cells are at 55 degrees C (as per my IR thermometer measurement) this is 30 degrees above the rating temperature.
So I calculate as follows:
Voltage Fall = 0.0023 x 144 x 40 = 9.9 volts.
The 144 is the number of cells in each circuit. The voltage fall of 9.9 volts puts MPP at about 58 volts -- which matches the operating MPPT on the XR/GP at the time. This calculation yields an almost 15% power fall below nameplate rating.

Current, however, has only a slight change (actually upwards) with temp. So, current ratings should be observed. That said, it would be best, for array testing, to measure its short circuit current (58 amperes for my system) rather than MPP current (53 amperes).

As for sun angle, I was measuring at the plane of the array.

One of the great things about your work on the inverter is that I can now turn my attention to physics/performance of the PVs. This is great.

Gordon

Me Bad , your right only the voltage is effected on IR loss. Heat actually increase current in SI panels, by about 1/10th the effect of the voltage drop

Unless your getting edge of cloud effect I doubt your getting 1kWmsq, in clear conditions , you will not usally see 1kWmsq , typical clear conditions here in Florida would be in the 930-950 range.

As for the drop off , it is the COS off the angle difference

Henry