New to Solar

 I am wondering if anyone can help. I have just had a solar system fitted with a Pylontech battery and Solis inverter. The installed capacity of the panesl is 3.6kWp and the battery is a US2000C. I am a low user of electricity and export the majority of what we make to the grid at the moment.I've applied to Scottish Power for an SEG payment which seems to be 5.6p per kWh. At the moment I am on a fixed rate until 2024 for the electricity I use from the grid but obviously prices are getting higher and higher. The battery is charging from the grid in the early hours of the morning, which to me seems wasteful as the money I can make from exporting is a fraction of the cost of importing. Obviously as the summer draws to a close the battery will run down even faster and presumably import more to charge it up.  What I would like to know is the following:

  1. How low should the battery be allowed to go to before it begins recharging - I believe it is set to around 18% at present. I know it can't go too low if I want the longest possible battery life.
  2. Is it possible to set the system so that the battery never charges from the grid but just stops discharging when it reaches the set lower limit?
  3. If this is not possible, would it damage the battery to manually switch it off at night as we go to bed before it hits the lower limit and then switch it back on again in the morning once the sun starts shining?
  4. If I can't do this, what is the most efficient way to manage the settings?
  5. Finally, unless you have a cheap night rate what is the point of charging the battery from the grid at all? It would seem far more sensible to just run the house from the grid once the battery runs down and then recharge the battery once it can be recharged from the solar system.
Im not very technical so please bear with me.



  • Alnat1
    Alnat1 Posts: 3,285 Forumite
    First Anniversary First Post Name Dropper
    I'm fairly new to solar and battery, fitted in March. I also have pylontech batteries but with a Lux inverter. Same 2000C as you but mine are set to go down to 10%. The manufacturer states the C version can go to 5%.

    My standard settings are load first, battery second, any excess to grid. No charging of batteries from grid.

    I rarely charge from the grid but if I want to I have to go into the app or online settings and alter them to do it. It appears your system has been set to do this every night.  Are you able to access the settings yourself to cancel this? You Tube vids helped me understand the settings but you could always ask your installer to change them.
    Barnsley, South Yorkshire
    Solar PV 5.25kWp SW facing (14 x 375 Longi) Lux 3.6kw hybrid inverter and 4.8kw Pylontech battery storage installed March 22
    Octopus Agile/Fixed Outgoing and Tracker gas
  • Reed_Richards
    1. It depends on the battery.  The minimum charge is usually between 10% and 20%
    2. That should be the default.  My battery stops discharging when it reaches 10% but will leak charge slowly over many hours so if it ever gets down to 5% it will charge from the grid up to 15%.  But that would only ever happen after days of cloudy weather
    I think something is wrong with your set-up or your battery is faulty.

  • rosewoodspa
    Thanks for that. It seems it is possible to reprogramme to what I want to do - if I can figure it out. As I said in my first post, unless you have a cheap rate at night, it seems mad to ever top up the battery from the grid. Unless of course that runs the battery so far down it ruins its life. At the moment its only pennies and I think my installer thinks Im fussing over a trifle but if unit prices do keep rising then I don't want to be paying for anything I don't need. On cloudy days when I'm only making enough to keep the house ticking along I don't want to be topping up the battery from the grid.

    Thanks for your help and any other suggestions anyone has.

  • Reed_Richards
    ... I think my installer thinks Im fussing over a trifle.... 
    If your installer really does think that then they don't know what they are doing.  Your battery should never charge from the grid unless:
    1. You tell it to
    2. Or its state of charge gets really low.  That should only happen after a few days of cloud and then it should only recharge a little.  
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