question

thepiper avatar image

Smart Solar fluctuating

I have a single solar panel on my van attached to a Smart Solar MPPT 100/20. Everything seemed to be working very well but today I switched my fridge on for the first time in a while an when I look at the Smart Solar app, I notice a massive fluctuation in the solar readings. It can swing from bringing in 1w to 150w and back to lower figures again within seconds of eachother. It never seems to settle at a steady rate.

Does anyone have any ideas why this may be? It didn't do that when everything was first installed and tested, but it's sat for a few weeks until turning back on today.

Any advice much appreciated. Thanks


smart solar set-up help
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"It can swing from bringing in 1w to 150w and back to lower figures again within seconds of each other. It never seems to settle at a steady rate."

It sounds like your battery was full, and the mppt was in the float charge state. Then you turned the fridge on, lowering the batt voltage, then the mppt moved into bulk charge state.

Keep an eye on the battery voltage, and the charger state, report back.

3 Answers
Justin Cook - Bay Marine Supply USA avatar image
Justin Cook - Bay Marine Supply USA answered ·

The MPPT should should swing around a fair bit as it looks for the "sweet spot" or, quite literally, the "Maximum Power Point", but if it truly never settles down then you may want to double-check your wiring and connections. Every time I've seen an MPPT swinging wildly around without ever settling into a (fairly) steady in/out, the issue has ended up being connections that are overheating due to poor crimps, undersized wiring, or loose connection bolts.

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thepiper avatar image
thepiper answered ·

Thanks for the answers.

I think it was just swinging around when items such as the fridge were first switched on. After a few minutes it seemed to settle on a steady figure. I'll keep an eye on it though and will keep your answers in mind also.

Thanks very much.

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cemdev avatar image
cemdev answered ·

Justin - thanks - I know this is from years ago, but you just solved my problem. Was a loose connection going into the controller.

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