Good evening, The output of my solar charger fluctuates from the moment the output power exceeds +/- 1000W. This is clearly visible on today’s and yesterday’s graph coming from Home Assistant. Also a detailed screenshot from VRM shows this. Today and yesterday was sunny without clouds. Anyone have…

I think you and I may have the same problem… [image] MPPT turning off and on again DIY Sunny day here shining on my ~4000 W of solar connected to the SmartSolar (part of an EasySolar 5000) driving a pair of 48 V LFP batteries each with own BMS, linked together by RS485 and…

Hi @StephaneB and @spicedreams I have the same problem on one of our installations. There we have two mppt 250/100 chargers. I don’t think both got damaged at the same time.. I think the bms communication is not stable. Hence the charger starts and stops constantly. I will go on site and try changi…

I have now disconnected the CAN cable, since CAN with my (unknown) BMS caused problems of which this might be one symptom. I lose any ability to sense the LiFePO4 state of charge, until I grok the BMS’ serial protocol to parse that value out. But actually the batteries seem to charge better without …

Good morning, An update. I haven’t found a solution yet, but I have a screenshot of the overall picture. The problem described in the first post occurs between +/- 950W and 1300W. This is clearly visible in the graph below. The problem persists, even when I disconnect the VE direct cable from the s…

Hi @StephaneB Do you by any chance running any heavy load during those times? I got the same kind of behavior with my 100 50 and 150 45 MPPTs. The MPPTs tend to draw less power from the panel during loads and they fluctuate a lot.

Hi. A 280Ah LiFePO4 battery is connected to the solar charger. This can be considered a heavy load, given its very low internal resistance.

Hi @StephaneB A load is something you run on a battery, say, an inverter, a DC Pump, a DC water heater, etc. Also, if possible, please upload the Battery Voltage and Current graphs corresponding to those above timelines.

I had a similar problem today, suddenly the charger output started fluctuating the same as in your screenshots. It seemed to stop shortly after the cooling extractor fans came on in my plant room, this could be a coincidence or it might be something to do with thermal management in the charge contro…

Hi @FuryJK98 , f it is a sunny day again soon I will try it with a heavy load and I will let you know what the result was.

Hi @VEC_WF , That indeed seems to show the same behavior. Do you still have the second part of the graph, namely when the output power drops back below about ±1500 W? It’s possible that this behavior appears again then. In my case, this behavior occurs between about ±950 W and ±1300 W. Which type of…

Strange MPPT fluctuations SmartSolar Charge Controller

DIY

spicedreams (Graham) March 23, 2025, 8:27pm 2

I think you and I may have the same problem…

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Strange MPPT fluctuations SmartSolar Charge Controller

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