Looked at the logs, and the system generated a peak input power of 488 watts at one point. Why is that notable? Cuz the STC on the two panels is 240 (x2=480). And it wasn't that cold, either ...
Vern, where are you sited?
That peak power is many times affected by ambient temperature and sometimes cloud edge effect. A few days ago I seen the yellow warning light on on one of my Classics and it was displaying "Over Current" on the display. The 3.0 kW array on that controller was putting out 3,400 and something watts and the input current had reached the limit for the underground service wiring and input breaker. The Classic was limiting it according to the input amps limit I had set in it to prevent kicking out the breaker.
It was a super clear and very cold day that caused it.
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Chris
Vern;
It is not uncommon for my 1500 watts array to produce 3% or even 5% over "rating" (1580 watts has been recorded) in cool / cold weather with snow on the ground. According to the Classic itself. Cloud edge effect (lensing) can also boost instantaneous values well above that for short periods of time.
Plus, I doubt the Classics are very meticulously calibrated. Depending on how the math is applied, rounding errors may inject a couple percent of "windage" to readings on the Classic. 8 watts is a bit less than 2% of 480.
Just how I see it from here. If I am understanding your comments.
Math is NOT my strong suit, either.
Tom
I wish the forum notified me when posts are made while I am typing.
I hate getting documented agreeing with Olson! :o
However, if we are saying the same thing it is probably more or less the facts.
Tom
The daily high power number is based on output power and not input power. Input power is not calculated but
you could get an idea by multiplying input current and voltage.
The input numbers are not nearly as calibrated as the battery side measurements at this time though.
boB
Quote from: Westbranch on February 18, 2013, 11:37:59 PM
Vern, where are you sited?
Southwestern New Brunswick, right on the Maine border.
Quote from: TomW on February 19, 2013, 12:17:54 AM
I hate getting documented agreeing with Olson! :o
Yeah, that could definitely change the course of your life! :o
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Chris
Quote from: boB on February 19, 2013, 01:41:54 AM
The input numbers are not nearly as calibrated as the battery side measurements at this time though.
My Classics seem to be pretty close on the output (battery) side. I have a high quality +/- 1.5% analog ammeter on my DC bus that shows total input power from all sources to the bus. The numbers on the Classics always seem to agree within a couple amps of what the analog meter says.
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Chris
Quote from: ChrisOlson on February 19, 2013, 10:09:43 AM
Quote from: boB on February 19, 2013, 01:41:54 AM
The input numbers are not nearly as calibrated as the battery side measurements at this time though.
My Classics seem to be pretty close on the output (battery) side. I have a high quality +/- 1.5% analog ammeter on my DC bus that shows total input power from all sources to the bus. The numbers on the Classics always seem to agree within a couple amps of what the analog meter says.
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Chris
Yeah, That's OK, but I'd rather it be closer, like within maybe +- 0.5 amps would be nice.
Some time hopefully. The hardware is certainly good enough. The input current
is not zeroed as good as it could be and the input voltage could be closer.
Software calibration can take care of that, Either before or after the fact.
boB