question

havard avatar image
havard asked

The 100/50 has volts, but low amps

Hi - a boat electician just installed 4 x 100 watts solar panels on my boat, and connected them to the MPPT 100/50, but I've never received more than maximum 7 amps. When checking the voltage going in to the 100/50, i have had up to 50 Volts, so the panels are working fine. I have seven 100amp/h batteries installed + the starting battery, and the battery for the windlass. I bought the 100/50 in Grenada, but are now in Guadalope - if there's something wrong with the 100/50, will it be possible to get a new one due to guarantee by another store than the one I bought it in? Thanks in advance

MPPT ControllersSolar Panel
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8 Answers
wkirby avatar image
wkirby answered ·

It's difficult to tell exactly without more details of your system.
What arrangement are your batteries connected in? 12V, all in parallel?
Also how are you PV panels connected I might assume 2S 2P. Do they all get good sun exposure?

400W on a 12V battery should give you around 30A in absolutely ideal full sunshine conditions.
Any shading will significantly reduce PV output.

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havard avatar image
havard answered ·

Hi. The 7 batteries are all in parralell. The panels are connected two and two together. We're in the Caribbean, so the sun is good.

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boekel avatar image
boekel answered ·

is the 7 amps on the input or on the output of the MPPT?
(7x50V = 350W)

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havard avatar image
havard answered ·

It's on the output, and the voltage is never higher than 12,7.

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JohnC avatar image
JohnC answered ·

Hi Havard. This reeks to me of a polarity mismatch somewhere within your panel wiring. It's not uncommon to see this, and perhaps a little carelessness with MC4? connectors is the reason.

If that's not it, a warranty should be easy to claim with the necessary proof-of-purchase, etc.

But I must say it - I don't much like your 7x (+2 more?) parallel batts. Presuming Pb's, the danger of imbalance destroying them is real. At the very least, when they're later into a charge period, give each a touch-test to determine if one (or more) is hotter than the others. It will need culling. And it's not really a matter of 'if' this will occur, it's a 'when' scenario.

Good luck though..

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Paul B avatar image
Paul B answered ·

Please check your panels that they are connected correctly as per this sample diagram.

Make sure ALL joins are of good quality and none are loose

check to make sure that each string has the same voltage. and that the connection polarities are correct, if you have 50 volts then the short circuit amps should be around 4 amps per string

remove the solar connections from the Regulator and in good sun put a amp meter across the neg and pos of each string and the amps should be about the same.

All panels in the same string must each have the same current output

the current output should be close to the panels rated output.



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christyler avatar image
christyler answered ·

Maybe the battries a charged and only need that much current

Try turning more things on and see does the charge current go up

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havard avatar image havard commented ·

I've found the solution. The mppt was place before the panel with all the fuses. We moved the mppt to be between the panel and the battery (next to the batteries), and that made the whole difference. Now it's givingjo to 20 amps

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ejrossouw avatar image
ejrossouw answered ·

There is a setting to limit the charge current on the controller. Can you confirm what it ?

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