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miya avatar image
miya asked

VRM Solar W - showing Negative Value

Hi All

I am curious - the PV is showing -1W - can anyone explain why this would be - or is this nothing to be concerned about ?

img-6290.jpeg

Thanks all,

Tim

VRMsolar
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @Miya

You know what curiosity did to the cat? :)

It's likely just an addition error with your 4x mppts. Nothing to be concerned about. 1W isn't much energy anyway.

But you raise a related point, visible on your very screenpic (watch it working for a while). The battery Amps indicate accuracy to 2 decimal points, but the second is always zero. And on a 48V system the result is 5W steps. I can live with that.

The DCPower is a calculated figure, and does much the same. Except instead of a zero it sometimes shows a 1 or a 9, or less frequently a 2 or an 8. So it's actually highlighting it's own calculation errors rather than providing an accurate A.

Pedantic it is, but VRM shouldn't be showing A to 2 dec places here, as it implies an accuracy that doesn't exist. The A in the mppt box might be reporting a best-effort 2-dec-place, but that might be fair enough with the new high V mppts.

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miya avatar image miya commented ·
Hi JohnC, Ha ha ha... yes... I may go the way of the cat one day :-).

Thanks for the full response - which makes sense to me. You make a good point about reporting 2dp in some values. Thanks again.

Ta, Tim


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