question

merv avatar image
merv asked

I have 1200 watts of panels but by charge controller shows around 200 watts, 70volts ,3.5 amps Is this correct

Hi the details doesn't make sense , at start up in the morning after using all night, shouldn't the input from the solar be a much higher number. It's a mppt100/50. Thank you

MPPT Controllers
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3 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

There are many variables:

The panel specs are based on a sun angle of 0 degrees and bright sun, The angle of the sun can significantly reduce panel output.

Partial shade on a panel can reduce it's output significantly. For example, one cell shaded could reduce the panel's output to half it's unshaded value.

Current battery state dictates how much charge your batteries can accept so if they are near 100% state of charge, there is no where for the solar energy to go.

If your battery bank is 12 volts, the MPPT 100/50 will supply AT MOST 600 watts to the battery (50 * 12).

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merv avatar image merv commented ·

Thanks, so I would never see anything past 600 watts ? The most I've seen is around 550. I just assumed on very sunny days I would see close to 1200 watts

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kevgermany avatar image kevgermany ♦♦ merv commented ·

If you put in a bigger MPPT controller, you'll probably get more out of the panels on sunny days. Angling the panels towards the sun will help.

Just an observation - did you check the voltage specifications of the panels in winter conditions? You might end up with too many volts for the controller. It will safely limit current to its capacity, but will blow If you have an over voltage situation in freezing conditions.

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kevgermany avatar image
kevgermany answered ·

Also depends on battery type. Lead systems accept charge at a much lower rate than lithium.

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merv avatar image merv commented ·

They are 6 volt deep cycle

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kevgermany avatar image
kevgermany answered ·

Another thought. Add a second MPPT 100/50. Split the panels between the solar controllers and wire the controllers in parallel to the batteries.


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