question

as-solar avatar image
as-solar asked

MPPT 100/50 will not wake up, 40v on PV input

My Smartsolar 100/50 will not wake up!

- Three sets panels in parallel, each string at 40v on RV roof

- They are combined into a single pair of wires, voltage 40v between them when disconnected from the MPPT (polarity is correct)

- Difference between negative wire and MPPT PV inputs: 40v

- Difference between positive wire and MPPT PV inputs: 0v

- Battery plugged in, voltage 12.6v between MPPT battery inputs

- Blue light blinking every few seconds, this never changes

- Have tried swapping the two PV inputs, makes no difference


Once I plug in the PV wires and measure the difference between the PV inputs on the MPPT, it's 0v.


MPPT Controllers
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3 Answers
Daniel avatar image
Daniel answered ·

Try to powecycle (removing all wires and connect again) the whole unit. Maybe with breakers or fuses if you have some. I had this sometimes with a 75/15 if I switch the PV on and giving it it's 30V in one switch. The MPPT don't recognize the Input for some reason.

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Justin Cook avatar image
Justin Cook answered ·

@AS_Solar, you say that polarity is correct, but from your reported measurement it appears that you have the polarity reversed: you report 40v at your PV negative, which means it's actually your PV positive.

The charger will not apply any load to the panels or, indeed, really even recognize them as being connected if they are connected in reverse polarity.

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bfh avatar image
bfh answered ·

I had the same problem this morning. Switched the charger off/on (maintenance mode) in the bluetooth app. Working like a horse again :)

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