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pekkaj asked

MPPT power output (by app) is affected by load

According to android app, MPPT 150/70 power from panels is affected by load on battery in same system. When load, MPPT power drops accordingly. Is that a feature in monitoring or does the battery load actually affect negatively to solar power gain? Load is made by Multiplus II and measuring device is BMV-712 which is connected to MPPT by VE.Smart.

MPPT Controllers
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mvas answered ·

Need more details about your PV array. So, tell us ... How many volts, amps and watts is the PV Array producing when the load is off vs when the load turns on? The BMV-712 is measuring the volts and amps, in / out of the battery bank. The amps charging the battery bank will decrease when the load is on.

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pekkaj avatar image pekkaj commented ·

PV is only two panels total 800W (~14A). Isn't MPPT power info coming from MPPT directly?

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pekkaj answered ·

mppt.jpg

Here is an example. Down spike is fridge.


mppt.jpg (294.5 KiB)
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nickdb avatar image nickdb ♦♦ commented ·
Remember, every 10 minutes the mppt will track the power point so you will naturally see dips when loaded.
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pekkaj avatar image pekkaj nickdb ♦♦ commented ·

That could be it, didn't know such feature exists. And curve history gets smoothed out so maybe that's why it's not seen in longer history.

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thanar avatar image thanar pekkaj commented ·
If you are referring to the sudden drops in power output every ten minutes, this is a feature of the controller trying to better locate the panels' maximum point, has nothing to do with the DC bus voltage.
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thanar avatar image
thanar answered ·

You’re probably close at your controller’s maximum output current. What’s happening is, depending on the voltage of the battery, power output changes, since P=V*I, while MPPT output current stays steady. That’s normal.

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pekkaj avatar image pekkaj commented ·

MPPT's max output is 70A so there should be headroom.

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