A-Si Thin film Off-grid system

Hello to all solar experts,

I am mainly a grid-connected system developer in Greece but with some experience in off-grid systems as well.

However a client ask me to fix an off-grid system which actually worked fine for one day and someone ignorant install.

When I visited the installation I found out many things I did not like
The system was made by
15 solar panels a-si which the installer claimed to be 40Watt each of them, they are installed on the roof and they do not have lebel on them.
1 solar charger SCC 20A conergy 24V
1 solar battery 260Ah/24V
1 solar inverter 1000VA unknown manufacturer

As the client said the system was supposed to support a refrigerator (85W), a small TV and some 11Watt lamps.

He claimed that the system worked fine only for a couple of hours. After that he realized that he could not function the refrigerator and he switch it off. Many times the inverter switches off even having only 2-3 lamps turned off.

I assume that the inverter goes off propably because of the battery's low voltage.
I also believe that for the A-Si he probably needs a different solar charger in order to charge the batteries correctly.

My belief is that when the system operated at the begining it did not manage to charge the batteries corectlly because of the wrong charger he used. After that when the devices started to operate he lost the battery because of very deep discharging. Now he has a very weak battery and only operates 1-2 lamps. The inverter every 1-2 days goes off because probably of batteries low voltage.

Any idea of what is the best thing to do now?
Should we find an appropriate solar charger for the thin film modules and replace the battery?

I would appreciate for your opoinion


  • Solar GuppySolar Guppy Solar Expert Posts: 1,987 ✭✭✭
    Re: A-Si Thin film Off-grid system

    Asi panels are high voltage, so to harvest the potential energy you will need a quality Mppt control. MorningStars Tsmppt, Outback Flexmax 60 and Xantrex WX-Mppt are the choices.

    The New MorningStar Mppt comes in a 45 amp version and cost wise would be the best option for using the Asi panels. Asi typically is about 90V

    I would guess the pwm charger now installed is blown up, very few can handle Asi panel voltages and the battery's are getting no charging based on your description of the site
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: A-Si Thin film Off-grid system


    Firstly I would find out the specefications of those panels. The original installer must be able to tell you that. If not whip out a voltmeter and ammeter on a clear day.
    Once you know the voltage and how the panels are wired you can find out whether the charge controller is suitable or not. Also check whether the charger is actually putting anything into the battery.

    Determine the total daily loads on the system. How long is the fridge on, exactly how many lamps and how long are they on for? With this you'll know whether the system is correctly sized or not (both in terms of panels and battery).

    Once you've done the above you should be able to make a decision about which bits to keep and which to replace.
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