Solar panel erratic charging

[Pagetslady]

Hi, I have 120 w of solar, my question is when they are charging through a MPPT Controller if they are charging at 5 amps should that be constant if the sun stays constant, mine seem to jump about a lot rarely staying constant for more than a minute or two often going to 0 then up to 7 am then 3 am I am happy with them generally but wondered if this behavior is normal. Thank you in anticipation.
Mike

 

[William_H]

I believe that MPPT use a multistage charging profile like a alternator controller or mains powered charger. However this controlling of charge beyond the bulk stage only occurs when batteries are fully charged. I would suggest a simple test would be to turn on loads like lights fridge etc to see if this changes the fluctuations. If the fluctuations don't change significantly one might have to assume bad panel or wiring.
Test the panel using an amp meter connecting the panel positive via the meter to the battery positive. (and negative of course) This should give a steady charge current of around 5 amps. If this fluctuates check all the wiring to the panel and the connections to the panel. You can put an amp meter directly across the panel terminals after disconnecting from the battery. Fluctuations of amps or volts at the panel terminals might indicate bad panel.
If charge current is steady with controller out of the circuit then you have a bad controller or back to your original question it might be normal but I doubt it. Unless of course you have one of those Chinese so called MPPT controllers which are really only pulse width modulated.
ol'will

 

[Graham376]

Just wondering if you're getting intermittent shadows from either your boat or adjacent ones as they move a little, particularly with series panels that can have large effect on output.

 

[lw395]

Need to look at the volts.
If the controller decides the battery has had enough, it will turn the current right down.

 

[ryanroberts]

My set up (~1Kw over 4 amorphous panels and an MPPT) is very variable in marginal weather, even during bulk charge.

 

[Pagetslady]

Thank you everyone as we rarely get continuous sunshine in Fleetwood marina although I have noticed this intermittent amperage in the Channel Islands it is possible it's because the batteries are already full. I shall check it out more thoroughly.
Mike