Is this normal or anything to worry about?

I'm new to solar and just recently purchased a Zendure Superbase 1500. I also bought two 12V 180W BougeRV panels. They have a VOC of 21V, I connected them in series and then connected to the Zendure via XT60 connector(which accepts 12-60V VOC). They are constantly going up to about 180W then dropping to about 60-70W. This just repeats and repeats. There are no clouds in the sky. Is this normal?

Edit: I hooked in parallel just to see what would happen and it seems to be holding steady around 168W only occasionally dipping down to around 100W. i.e. still fluctuating but not as much. I'm just wondering because I have two 12V Rich Solar panels in parallel and they don't fluctuate like these.

Kelper said:

Is this normal?

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Yes but No. An MPPT controller will 'scan' the range of voltage in order to determine the voltage that gives the best Power. Since conditions change as the sun moves, the will periodically rescan. Everybody that builds an MPPT comes up with a different algorithm for how and how often they scan and the difference in the algorithms can make a difference on how effective the MPPT is.

From the description, it sounds like the controller is never settling in to a single 'best' voltage and just keeps scanning. That is not normal.

First, check all of the connections and make sure there is nothing loose. (A loose connection can trigger a rescan every time it re-connects)
Second check to make sure all input requirements are met. Maybe there is some weird behavior.
Third, check all the connections to the battery. This is kind of reaching, but maybe something on the battery side voltage is triggering a re-scan.

If none of the above are the issue, maybe the unit is bad or has a design flaw)

It seems that I have a behavior similar to you. My MPPT controller needs 0.9A to work properly.

Some charge controllers power their electronics from battery power, some power their internals from PV power. Most separate direct to battery charge controllers' power by PV power.

Most All-in-One inverters power SCC circuitry from battery power since they require inverter to also be operating to charge battery which can take a minimum of 60 watts or more of power. You can sometimes have a situation where PV SCC produces less power than SCC charging overhead power consumption, so you end up with a net loss of battery power. Many AIO inverters do not check for this situation since the inverter consumes much more idle power than the actual SCC controller board.

When powering from PV power, sometimes at low PV illumination (like early morning) the controller will detect Voc rise then fires up controller only to have the extra load collapse the PV voltage due to controller's internal overhead power consumption. It tries to start up again after a few seconds, hopefully with greater PV illumination to supply the necessary controller overhead power.

The advantage of powering controller by PV power is you avoid the 'Catch-22' situation of depleted battery not being charged because there is no initial battery power to start up charge controller. The disadvantage is the stuttering startup at low illumination on panels.

There are a couple of other situations where charge controller will cut back production. Obviously, when illumination drops due to clouds it will have lower output production.

Other situation, many folks do not realize, is any generated PV power must be consumed either for charging battery or loads on the system. If battery is charged and there is little power consumption from loads on the system, the charge controller will back down production to meet demand even when there is strong sun illumination available. Controller lightens load on PV panels allowing PV voltage to rise toward Voc where illumination generated current is re-absorbed into panels and dissipated as a little extra heating of panel. With panel efficiency about 20% the extra panel heating power can only increase by 20% and is not damaging to panel.