MPPT power output (by app) is affected by load

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pekkaj asked May 13, '23

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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Answer 1 · 2023-05-13T14:10:25Z

mvas answered · May 13, 2023 at 02:10 PM

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 commented · May 13, 2023 at 02:32 PM

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

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Answer 2 · 2023-05-14T09:27:00Z

pekkaj answered · May 14, 2023 at 09:27 AM

Here is an example. Down spike is fridge.

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nickdb ♦♦ commented · May 14, 2023 at 09:41 AM

Remember, every 10 minutes the mppt will track the power point so you will naturally see dips when loaded.

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pekkaj nickdb ♦♦ commented · May 14, 2023 at 03:33 PM

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 pekkaj commented · May 14, 2023 at 05:33 PM

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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Answer 3 · 2023-05-14T10:03:11Z

thanar answered · May 14, 2023 at 10:03 AM

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 commented · May 14, 2023 at 03:30 PM

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

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