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kernowsolar avatar image
kernowsolar asked

MPPT 100/30 number of panels question and amps. Panels are in Parallel

Hello, I have noted that the MPPT 100/30 IS restricted to 880 watts (24v), and 30 amps.

I have three 245w panels (735w) connected in parallel, each with an 8 amp output (24amp). Is it safe to add another 245w/8amp panel? So I would be running (980watts and 32amp) in total.

Will the mppt just absorb the power my extra panel produces, in the rare event they ever pump put their capacity of 32 amps?

I ask as, even with empty batteries in the morning, in full sun, my panels are producing 12 amps max during the bulk charge stage, no where near the 24amp they are capable with. As soon as it goes cloudy, my panels can produce as little as 75 watts.

I am trying to maximize the power I can get from my panels, whilst still having a system that is safe.

Any help would be appreciated

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4 Answers
ddickov avatar image
ddickov answered ·

Hi there just some knowledge of mine I hope it’s useful, I would only ever operate in the parameters of the mppt, I would suggest ideally to upgrade the mppt even to the 50a model as over sizing is always better than undersizing it in my opinion, I would double check the mppt manual for over panel voltage rating and current, as too much of either can damage the mppt beyond repair and I would say load current is dangerous if not operated within the devices limits, victron will have extensively tested this exact question if you contact them I am sure they would advise either way, but I think it would be ideal to change the mppt for a larger one as if you add more panels in the future it would be so much simpler.

Hope it helps a bit

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Alexandra avatar image
Alexandra answered ·

@Kernowsolar

What is the voltage open circuit of your panels?

2 series x 2 parallel, if your VOC is not above 100Volts you should be fine.

Your panels can produce higher voltage if it they are colder than 25°C.

4 in parellel would be over amping the input also not a good idea.

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kernowsolar avatar image kernowsolar commented ·
Hi Alexandra, the Voltage Open Circuit is 37.3
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kernowsolar avatar image
kernowsolar answered ·

Thank you Ddickov and Alexandra, let me get out to the panels in a bit and I will find out the information you requested. Thanks for your help

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solgato avatar image
solgato answered ·

To take full advantage of your panels you really need a bigger charger.

If you want to stick with what you have and add a fourth panel, you can wire them in Series Parallel creating two strings, each consisting of a pair of panels in Series, provided they are all the same and getting equal sun.

Doing this will feed the MPPT a VMax of 74.6V and 16A. By increasing the voltage to the MPPT by wiring the panels in Series, the charger will be able to do a better job of providing power when panel voltage drops. This is one of the main benefits of MPPT and the reason you want to feed as much voltage to them as possible by wiring panels in Series, not Parallel.

To get closer to your panels potential of 40A @ 24V, you could get a second charger and run it in Parallel with each charger being fed by a string of 2 panels in Series.

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