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Jay Kote asked

Suboptimal power point tracking on SmartSolar MPPT (100/20)

Testing at the point where wires go into the SmartSolar input terminals with a Sun MPPT tester shows the optimal power point to be at 330 - 350W mid-day sun. But SmartSolar is locked at voltage and current suboptimal to this and only producing around 150 - 200W (max). Believe there is some configuration problem. Any thoughts on how to diagnose and fix. (Unfortunately another brand MPPT has locked correctly, which is why we suspect SmartSolar is not configured right in some way.)

MPPT SmartSolar
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klim8skeptic avatar image klim8skeptic ♦ commented ·
@Jay Kote One thing that will limit the output of a mppt is the battery voltage. If your battery is at the Absorption (or float) voltage, the mppt will limit the output current (power) to maintain the battery voltage.


Post the panel specs, the voltage & current the panel tester displays, and the pv voltage & current, and the battery voltage & current for the mppt.


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Jay Kote avatar image Jay Kote klim8skeptic ♦ commented ·

That was a thought. We have observed this when in "bulk" charge when the battery was low. We did it this way to help isolate problem.


Then getting tired of being able to only test after battery had been drained, we decided to turn on Victron inverter and add a 1500W load (hair dryer). Same problem. The units MPPTs reported tracking point relative to optimum point is not max. And watt out is again 30+% below expected.


Now one possibility to explain this is somehow the smart solar doesn't care about load, it is only interested in battery status. But that would be a second problem. Because the plan is to add a relay so that when battery is full and Sun Max, shunt excess power to hot water heater. Is there a setting in inverter, MPPT, (or Cerbo) that we need to check to ensure it knows not to limit itself based on battery status?


(We also thought this was solar issue. But that is why we obtained MPPT tester and tested their performance at the point of breaker to wire to smart solar MPPT. )


Again this comes down to some kind of configuration issue.

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beat avatar image beat Jay Kote commented ·

There is a MPPT algorithm issue with RS 450/100, but the algorithm seems different from the smaller units.

Do you have a GX device ? You may be able to solve that issue and control your water heater using a Cerbo GX or smaller GX device, controlling externally your MPPT charger. (and use the NodeRED to fine-tune your control). Just a thought. Maybe an overkill.

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2 Answers
JohnC avatar image
JohnC answered ·

@Jay Kote

Have you actually watched the 100/20 track? You can do this by setting up Victron Connect Trends on PV Volts and Amps, and max resolution (~per sec).

It will only track when it's trying to maximize power, and then only every 10 minutes. So if you're making load changes, etc, you'll need to wait up to 10 min for a reaction.

There's no configuration involved with the tracker itself.


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Jay Kote avatar image
Jay Kote answered ·

Using BT and phone, we have watched the watts, voltage, and amps MPPT is putting out. It is a fraction of the available watts using the solar panel tester. We will read your response carefully and follow accordingly and check including giving minimum 10 min of time to see if there is a change. But wattage output is continuous and as said it is a fraction of what it should be. Thanks for suggestion!

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JohnC avatar image JohnC ♦ commented ·
@Jay Kote

If it's actually tracking you'll see clearly a 'triple spike' every 10 min (takes some 10 sec or so to complete). Best seen on pv V and I, but W should show it too. But it won't track at all if it's reached target V.

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