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Going beyond a 6kW inverter(s) on single phase

  • 27-09-2021 2:04pm
    Registered Users Posts: 70 ✭✭

    I have 6.5kW of panels on my garage (built this year with planning permission including the PV array) connected to a 5kW inverter (Alpha ESS) and 11kWh of battery storage. So far it's providing around 70% of my electricity needs, but I haven't had it over winter so I assume that number will go down. In terms of usage, I have an 8kW heat pump and an EV. The only non-electric appliance in my house is a gas hob which I'll eventually switch to an induction one - real time air quality sensors are good motivators. My house can likely hold an additional 12kW of solar panels. Oh, the garage's roof has a 30° pitch, while the house's is 45°. In addition the garage is partially shaded by the house.

    My current system works well, but during the winter when my electricity needs will grow larger, it will fall short in two ways. First just in total generation. I suspect I'll be getting between 5 to 10 kWh per day in winter due to the size and position of the panels. Second, the inverter maxes out at 5kW but the heat pump will have stretches where it uses 6kW or more. The remainder from 5 kW has to come from the grid even in full sun and a full battery.

    I'm wondering if it would be possible to install PV on my home's roof and connect it into a 10kW inverter. I'm aware I'm limited to a 6kW export, but if the system was designed to limit my exports to that amount, is that an allowable setup in terms of ESB rules?


  • Registered Users Posts: 552 ✭✭✭idc

    Did you ask SolarHome has anyone else tried this with the 5kW inverter? I'm guessing they havn't done this before or no one has pushed this an option? They've mentioned to me before if I wanted to expand they have installed for other customers a 1kW inverter and then the Alpha is switched into a hybrid mode so it is aware of the other inverter and has a meter tracking its output.

    Not necessarily of use now given you already have the 5kW inverter but Alpha have a 6kW model now.

    The export limiting capability does work though as my inverter was accidentially set to 0 exports due to miscommunication I had with Alpha support staff. Only noticed after a month or two that my inverter after filling the battery always tracked my usage!!

  • Registered Users Posts: 12,090 ✭✭✭✭KCross

    but the heat pump will have stretches where it uses 6kW or more

    I dount very much your heat pump uses that. The kW rating of your heat pump is what it puts out in energy, not what it takes in as energy.

    You said your heat pump is rated at 8kW and its probably got a 4.5 COP (or therabouts) so in reality the most it will be using is about 2kW and usually alot less than that.

  • Registered Users Posts: 70 ✭✭lyda

    I have this:

    It can draw up to 8kW - which I've confirmed via its control panel and via my solar PV app over the past six months.

  • Registered Users Posts: 70 ✭✭lyda

    Yes, I saw the 6kW inverter. They apparently last around a decade so that's an obvious upgrade when that happens.

    And yes, there was mention of the 1kW inverter option for future expansion. I didn't get a clear answer on larger options so was wondering if people had experience with trying to do that.

  • Registered Users Posts: 12,090 ✭✭✭✭KCross

    That looks like a 16kW heat pump, not 8kW, so that could pull 8kW alright. That is a pretty big heat pump for a domestic scenario. Thirsty I’d say!?

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  • Registered Users Posts: 552 ✭✭✭idc

    Did you look at mp3guy's thread ?

    He has a 5 and 6 kW inverter setup on single phase.

  • Registered Users Posts: 994 ✭✭✭Mr Q

    Is there an option with an Alpha ESS to add a meter into the system? With a SMA system and some others you can add the meter on the power connection coming into the house, this then allows you to set the maximum that will feed back into the grid.

    Not sure how the ESB view these but might be an option. I plan on doing it at some stage.

  • Registered Users Posts: 552 ✭✭✭idc

    The alpha ESS can configure the percentage feed back to grid.. My system was accidentally configured to 0% feed to the grid. With that setting once battery was full no matter how much sun was hitting the panels it only produced exactly what the load of the house required. Talking to the guys who install AlphaESS systems then seem to only consider adding a 1kW inverter alongside the AlphaESS 5kW inverter so I get the impression they have never configured it this way to limit say a pair to ensure the combined pair at 10kW can only export at most 6kW.

  • Registered Users Posts: 749 ✭✭✭buzz11

    When you say "real time air quality sensors" do you really have these? Can you post some info about them?


  • Registered Users Posts: 70 ✭✭lyda

    I used the one mentioned in this project:

    When I saw CO2 spike when I turned on my gas hob I borrowed a friend's sensor (Purple?) which tracked particulate numbers and nitrogen oxides. And this was just a hob boiling water. And from what I read that's higher than what electric manages.

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  • Moderators, Sports Moderators Posts: 18,785 Mod ✭✭✭✭slave1


    At present I have 6kWp on house linked to Solis 6kW Inverter, all equipment in attic, EDDI and Zappi2

    I am in the process of installing AE 20kWh LiFePo Sofar setup next to consumer unit

    I am planning two new arrays, 4.2kW panels SW facing and 3.6kW panels E facing.

    My query is should I get an ordinary Solis 6Kw Inverter or a Hybrid for additional batteries at some stage.

    I think another inverter is straightforward and should not upset current setup but am unsure about whether the hybrid inverter (with batteries attached) would "fight" the Sofar both in terms of charging and discharging.

    Any thoughts?

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  • Moderators, Home & Garden Moderators Posts: 5,880 Mod ✭✭✭✭graememk

    All I know 2 ME3000's fight each other! but its doable but requires external control.

    I wonder, what if you got a 6kw hybrid, and only connect batteries to them now, and then its a simple connect the PV next year - Also will get 5KW discharge/charge (you will essentially have 400ah cells too so 400amps out of them is still only 1C)

    Not sure how it will tie into the myenergie system though.

  • Moderators, Sports Moderators Posts: 18,785 Mod ✭✭✭✭slave1

    I don’t want to connect current batteries to a single inverter as it may not provide enough juice, with the Sofar it will take the excess from both PV and shove into batteries, that’s the advantage I’m after…

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  • Moderators, Home & Garden Moderators Posts: 5,880 Mod ✭✭✭✭graememk

    There is someone with a similar setup, but smaller. But I dont think it will do what im looking for it to do :

    Doesn't seem to do any charging when there is no PV coming into the hybrid.

    If there is solar attached, and suppling some power, it will take power from your other inverter aswell (also thus making me think that there is no DC-DC converstion in the inverter, its all put to AC and then battery is then charged from "AC" and a 48V charger.

    Also there "should" be a separate inverter for the 48V system then too, but total output would be limited (via firmware!) due to cable size, mcb ratings etc.

  • Moderators, Sports Moderators Posts: 18,785 Mod ✭✭✭✭slave1

    Hmmm, and that’s with a single battery setup so basically it’s saying there’s no “passthrough” when hybrid off which kinda makes sense.

    So I haven’t seen anyone here mention it so may as well ask… there anyone here with TWO inverters and both a Sofar type battery setup AND batteries attached to their Hybrid inverter?

    I think the answer is going to be no.

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  • Registered Users Posts: 2,244 ✭✭✭SD_DRACULA

    I have read somewhere that for the Solis you cannot have more than one hybrid in the same config/house as they would fight each other.

  • Moderators, Home & Garden Moderators Posts: 5,880 Mod ✭✭✭✭graememk

    your looking for an edge case of an edge case!

    Although I'm almost sure that it will be no issue, as the ME3000sp will work without the solar CT, It just uses that for monitoring the house load.

    you can put more than one wire through the Solar CT too if there is 2 inverters.