Help with off-grid solar setup...?

I wonder if the Community can help me... I am trying to set up and off-grid solar panel system with battery storage (not a feed in system), but I am running in to an issue - theMPP controller is showing input voltage but no Amperage/charge going to the batteries.

I have 8 panels in series with the following specs :-

Nominal Rating - 77.5W

Current at mph - 1.11A

Voltage at mph - 69.9V

Short Circuit Current - 1.22A

Open Circuit Voltage - 90.5V

Max. System Voltage 1000V

The MPP Controller specs are:-

Max. Power - 80A

Peak power of solar cell - <1000W

Battery capacity configuration - >800AH

Batteries X2 (lead acid) 12V 120AH in parallel.

Inverter 12v DC - 220v AC 10000W peak 4000W load.

Being in the currently cloudy UK I haven’t seen the voltage go above 79.6v, I’ve even tried each panel on its own which shows voltage but no amperage. Does the array/MPP require a greater capacity of batteries, or a lesser rated MPP for the current amount of batteries?

The connecting cabling is 4mm PV 1000v DC rated, and the array has an isolator prior to the MPP. The batteries are new an float charge is above that required for the MPP to function.

I must be doing something fundamentally wrong so I’m asking for some help, any helpful advice will be gratefully appreciated. Thanks.

5 Answers

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  • 1 month ago

    We call them charge controllers, the mpp device you are connecting between the panels and the batteries. Their job is to not charge your batteries too rapidly.   First, you are getting max of 80 V, which is about 10v per panel, since they are in series.  Your charge controller isn't getting much to work with.  It may be difficult to determine if your charge controller is even working at this point.  

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  • 1 month ago

    There may not be a problem Police, just looking at your equipment list, your array short circuit max is 1.11 amps feeding into an 80 A controller? If it isn’t clear and sunny, the readout on your controller might read zero because it’s only getting less than one amp. My C60 controller doesn’t show anything below 2 amps, but I know I’m getting current if I carefully monitor the battery voltage and see it speaking up a little above 12.6 with my loads turned off. My array maxes out at 34 amps in the sun, on overcast days, 2 amps is not uncommon.

    My suggestion is try putting a hand held ammeter in between the solar array positive and the positive input for the controller, a decent DMM should have a 10 amp input someplace. That will tell you down to 1/100 th of an amp if anything is coming in even if the controller still says zero. If that isn’t working for you I’d make a call to the tech support guys at the controller manufacturer, they always have a rabbit up their sleeves in situations like this. Keep after it, Rudydoo

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  • Vaman
    Lv 7
    1 month ago

    What about the terminals. Solar current is electron current. Suggested to use diode to control reverse current. I am just suggesting.

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  • 1 month ago

    HOW COULD YOU USE 79V SOLAR PANEL TO CHARGE 12V BATTERY PACK ??? WHO GAVE YOU SUCH A FOOLISH SET UP !

    THE BATTERY LOAD NOW ACTS AS A DEAD SHORT TO THE SOLAR PANEL AND SURE IT WOULD NOT WORK AT ALL.

    REPLACE SOLAR PANEL WITH AT LEAST 14V 80A TYPE TO CHARGE THE 800AH BATTERY BANK !

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  • 1 month ago

    no way I can help over the internet, lacking schematics, full specs, etc. I'd contact the manufacturer of the charge controller for help.

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