help me interpret my solar output

[wincrasher]

I had a great 4 day weekend with the solar and electrical setup in my van. Went to the Alabama Hills and enjoyed the clear skies and amazing vistas.

I also was able to give my systems a workout. Carefree use of the intverter, plus running the stereo, lights and refrigerator.

My Victron BlueSolar 100/50 MPPT controller has the bluetooth dongle so I can monitor things on my iphone. I have four 100 watt panels from AM Solar.

Attached is the history from Sunday. Big use day with multiple uses of the inverter to run a toaster oven, coffee maker and microwave. I think I got down to 80% on my battery bank at one point. But the solar was putting out around 23 amps for quite a while. I didn't record my total AH used. What can you glean from these readings? I am particularly perplexed that the Pmax is 490 watts on my 400 watt system. How could that be?

[booster]

Most of the days show low harvest of less than 25ah (at 14.4v) per panel, which is pretty typical of not having the batteries run down very far, so the power not needed.


The one with the 490 watt max is suspicious as it is over 20% higher than rated, which would be unusual. Panels often do a bit better than rated, but that is a lot.



For that same day, the harvest is also very high at over 170ah, so that is over 40ah per panel. About 30ah is considered average by most people, but we have heard of harvests near 40ah per 100 watt panel at least once in the past.


You may want to check to see what the sun angle was where you were, as you may have hit the right overhead time and place. I have a spreadsheet that can be used to approximate the maximum available harvest for a day, so that also could be used to see what theoretical harvest max would be.



Any way you look at it, that was a very high output day.

[wincrasher]

Yes, I was drawing similar conclusions. That day I was intentionally using alot of power to see what it would do. The sun was extremely bright and a cloudless day. I was parked facing almost due east, and no shadows on my panels. Location is near Lone Pine, CA. Temps around 80 degrees.

I'd read a few bits about some MPPT controllers boosting output, but I was thinking it would be pretty marginal at best.

[booster]

Yeah, the MPPT controllers will boost output, but AFAIK that boost is only above what a PWM controller would give. The panels AFAIK are rated at their maximum power point, so I wouldn't expect them to be that much better. You may want to give AM Solar a call and see what they say about it.

[VanFan]

Originally Posted by wincrasher

I am particularly perplexed that the Pmax is 490 watts on my 400 watt system. How could that be?

In addition to the comments already made about the controller boosting your output and the sun angle, etc., you might consider the possibility that the Victron monitor's calibration is off. I only use Victron Connect to monitor my battery so this may not apply in your case, but with battery monitoring the Victron unit and the battery's state of charge must be manually synchronized from time to time. Maybe check the manual to see if there's a similar requirement with their solar controller monitoring? Just a thought...