question

mark-ruijzenaars avatar image
mark-ruijzenaars asked

Measurement accuracy during solar

Dear,

On my system I see when de MPPT/solarpanel is generating power that the measurement if the DC (calculation) and the AC output has a different pattern. I See this every day. On my system al users are off, except the modem and camera (continuous consumption is expected).


Can somebody explain this?

System: Multiplus II, Cerbo, MPPT, BMV702.

dc-and-ac-deveation-during-mppt.jpg

batt-mon.jpg

MPPT Controllerscerbo gx
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3 Answers
kevgermany avatar image
kevgermany answered ·

It would help if you also showed the VRM reports from the BMV.

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mark-ruijzenaars avatar image
mark-ruijzenaars answered ·

That's a good one! See below (same day):

batt-mon.jpg


batt-mon.jpg (43.5 KiB)
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kevgermany avatar image
kevgermany answered ·

Oops, missed it. Sorry. Was also looking for the MPPT panel volts/current graph.

First thing.

DC system is the difference between the BMV and multiplus values. So for example a fridge running off DC will draw current. This may be met by battery, multiplus, PV or any combination. Any load serviced by solar will not be seen by the BMV.

AC out can come from the inverter as a DC load, or from AC in.

So you have 3 different inputs, loads which may bypass the BMV. Loads like AC that are measured by the multiplus. And multiple graphs to reconcile.

AC in may also help.

I went through the exercise quite a few times on my system, got the numbers to tally (there are some inaccuracies, possibly due to timing differences in the measurements). And couldn't be bothered doing the work each time.

There's a new VRM release due soon, can create your own graphs. I want to use this to combine these values across the devices into a better summary.

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