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Anyone running a 3 phase solar inverter?

  • 01-05-2022 2:59pm
    Moderators, Motoring & Transport Moderators Posts: 6,521 Mod ✭✭✭✭

    Is anyone here running a 3 phase solar inverter. Trying to get some real information about things like unbalanced loads and the like.


    Shore, if it was easy, everybody would be doin it.😁


  • Registered Users Posts: 9 Sir Liamalot


    Studer Xtenders. You'll like 'em

    They're not solar inverters they're synchronising powerplants that can send proportional power in any direction.

    Inverter per phase you can stack phases.

    I've built a frequency shifting mini-grid with them.

  • Registered Users Posts: 9 Sir Liamalot

    I can't think of any reason you couldn't run 3 single phase GTIs, one per phase leg on a grid tied 3 phase supply.

    Any excess or imbalance ought to be exported (not shared).

    I find SMA pretty transient tolerant.

    They don't drop out on "grid instability" when you turn on for instance a 250W SMPS for the lights in the powerplant.

  • Registered Users Posts: 9,760 ✭✭✭Effects

    Why to you need a frequency shifting mini-grid?

  • Moderators, Motoring & Transport Moderators Posts: 6,521 Mod ✭✭✭✭Irish Steve

    That's going to be worth some further investigation, they should be capable of doing what I need, and could also possibly deal with the other non standard aspect of the system here, which is a large 3 phase diesel generator that comes on line automatically if the grid fails, so I have to make sure that the solar side doesn't try to back feed into the generator, as that will cause all sorts of grief, and as it's automatic, I can't rely on being here to manually switch things round. I don't want to downgrade to single phase, as it will make things more difficult as things like EV come on line, and my mig welder on a different phase to the house avoids problems with lights and the like being upset with the spikes that the welder can generate.

    I'm very mich aware that because the house is single phase, the loads on the inverter are going to be unbalanced, I have very little 3 phase equipment, but back in the day, I had a lot of heavy usage computer gear that couldn't be all run on single phase, unless I wanted to put in a commercial level feed in, which ESB couldn't do on a residential housing estate 30 years ago, so 3 phase was the only alternative.

    what's becoming very clear is that there's very few installers who are actually really geared up for dealing with anything outside of a bog standard single phase domestic installation, and getting accurate information is proving very hard, and I can't afford to make mistakes which then ends up with having to get different equipment to then have to try again.

    what is clear is that I need to make very sure that I make the righr decisions, so that we end up with a stable and reliable system that can do what's needed.

    Shore, if it was easy, everybody would be doin it.😁

  • Registered Users Posts: 2,508 ✭✭✭bullit_dodger

    I get the advantages of the 3x phase, the power delivery that you have, the options etc..... but I think your over thinking the benifits of being able to charge 2x cars etc at 11kw or higher rates Steve verses the complexity of doing it.

    Yeah, it's great an all.....but higher charge rates decrease the battery life of your car....and you have to ask yourself

    "super your car will finish charging at 2am"

    ....but will that "really" make a big difference to you over your car finishing charging at 5-6am on a single phase? Your probably asleep in either scenario. FIT exporting? You have to have the panels and the sun for it, so you can export at 11Kw.....are you going to spend €1000's so you can generate €100's a year? There being a cap of €200 before you get taxed on it I beleive.

    Ultimately it's your house, I've no skin in the game, but I think you will create a much more complex/expensive system for (somewhat) questionable benifits. As a developer myself, I totally get the background as to how you got there. Winchester disks in the 80's etc......but I think hanging onto 3x phase needs some serious thinking.

    My $0.02

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  • Moderators, Motoring & Transport Moderators Posts: 6,521 Mod ✭✭✭✭Irish Steve

    I guess that the issues are going to be a lot more complex. A very long time ago, before we moved to Ireland, we were caught up in the nonsense that went on in the UK with the disputes between the miners and the government, back in the 70's, and at that time, we were living in a little rented 2 up 2 down cottage that was effectively single fuel, electric, and we were then placed in the position of having no power on a rolling power cut basis of up to 16 hours a day with no power. I made a decision then that I'd never again be in a position of being dependent for everything on single source fuel, and have stuck to that concept ever since, usually by having both electric and gas in whatever house we lived in.

    Now, with the way that we are rushing headlong into eco friendly houses with no open fires, and no oil, and gas being the next target of the "Eco Greens", we are going to be faced before too much longer with having to use electric power for pretty much everything, and with the best will in the world, that's going to be a problem for a whole range of reasons.

    None of the power distrubutors can guarantee that their network won't fail, between the issues of cables being damaged, plant failing, and the problems caused by weather conditions, there will be times when power won't be available from the grid, and possibly for longer periods of time than we've been used to dealing with in urban areas, and that's without considering issues like no wind to drive the turbines, or supply disruption because of Ukraine, which has only served to highlight just how vulnerable we really are.

    Solar may help that, but to provide resilience, that needs batteries, and if we're not using other fuel sources for heat and light, then those batteries are going to need to be substantial, or we've got to have alternative generation methods, which for people like me means something like a fossil fuel powered generator. Yes, it might well be expensive to run as time goes on, but being able to have heat and light as we get older is not something to be taken lightly, so I have to think carefully about the best way to achieve that result.

    We're using around 5000 Kw per annum at the moment, but that's going to change significantly, we're going to be heating water using electric before long, partly because using oil to heat water is going to (already has) become uneconomic, and even if we end up with only one vehicle between us, that vehicle is going to be electric for a while, even if hydrogen becomes a more acceptable fuel, that technology is some way off, and may not become main line in my lifetime.

    The other consideration is heating for the house, and no matter how we look at it, we're going to be pushed into heat pumps by our "Eco greens", even if it's not the most suitable technology, so our electricity usage is going to be a lot higher than it has been in recent years, simply because we will end up moving other energy sources over to electricity.

    If we're running a heat pump, that's likely to be somewhere in the 6 Kw sort of size range, so that one item is going to get close to the potential capacity of most single phase Solar systems that are being offered at the moment, and even a basic single phase feed from ESB or whoever that's rated at 63A, so not an enhanced supply is effectively (round figures) 16 Kva, and it's not going to be difficult to see that limit having to be raised to ensure that people are not blowing main fuses on a regular basis. Most houses that have showers are using electric heating for the water, mixer showers that use hot water from a tank are not the norm, so you could be looking at 9Kw per shower, and that's already causing issues where devices to prevent 2 showers being used at the same time are having to be put in.

    We're still going to need things like cookers, and hobs, and fridges and freezers, so the option for the electric suppliers is likely to be a challenging one, they're going to have to increase the fusing to domestic users to allow them to be able to draw somewhere around 80 to 100 Amps, and they are unlikely to go the alternative route of having more 3 phases supplies, as that has much higher risks in a domestic environment, due to the phase to phase voltage being almost double the present single phase voltage. Charging EV's as well will add to that issue, so the upgrades to infrastructure in terms of new cables and transformers to be able to deliver that load is not going to be easy or cheap.

    "They" will be encouraging us to do things like shop less often, and 50+ years ago, very few houses had freezers compared to now, we'd be struggling to cope without them now, with the way that food supplies have changed, freezers and fridges are an essential now, and yes, if it's not opened if the power is out, a freezer is safe enough for at least 24 hours, but we've seen power outages of over a week in recent times even here in Ireland.

    So, I'm going to be doing my forward thinking and planning very carefully, and it's not easy, as getting a realistic view on where things are going to go with energy prices is impossible, and we don't know what new technologies may come along to help reduce the energy spend.

    Reading many of the posts in this forum is revealing that most solar systems that are going in at the moment are not going to be able to provide the power that is going to be needed to meet the demand once oil and gas are effectively out of the equation, and what makes it worse, quite a few of the solar suppliers are not actually warning people that they will be using significant grid power at potentially peak rate charging periods, even if they put in substantial solar systems, because the storage and inverter capacity just won't be there to meet the peak loads. What makes that even worse is that Ryan and his cronies are actually seeing multiple rate billing as an answer to demand. I'm just glad I won't be having to tell my children that they can't have their hot meal yet because the electric is too expensive, and they will have to wait till the price comes down a bit. That's beyond pathetic, and how do they propose to deal with things like heat pumps that need to be kept running 24/7 to keep the heat in the house stable.

    And yes, winchester discs in the 80's/90's, 11 Aluminium platters in a stack about 12" tall, 18" diameter, had a capacity of 300 Mbytes, (I can get many multiples of that on a chip the size of my thumbnail now!) and they needed 6KW of power for 30 seconds to spin them up to speed before they could be read. When I first put the machine in here, I regularly dropped the voltage here to below 190 V for up to 15 seconds at a time, until ESB discovered that we were not on the correct transformer, once they changed it, "normal" service was restored.

    It might be a while, but I will post up some of the route we end up going with, phase 1 today was completing the removal of 15 fluorescent tubes and replacing those tubes with LED equivalents, phase 2 tomorrow is to install the Shelly 3EM that's arrived, so that I can start getting some more detailed information on daily and hourly usage, with the peaks being captured. I suspect that I'm going to be driven demented by trying to get Home Assistant working for a lot of this, it's been a very long time since I was coding at assembler level, I've an Intel NUC that won't run Windows 11, so that will be an ideal unit to use for this, I did the SSD set up using the laptop a couple of days ago, so hopefully, it will just be a case of swapping in the relevant drive to get the basic system up and running, then we'll see where this goes.

    Shore, if it was easy, everybody would be doin it.😁

  • Moderators, Sports Moderators Posts: 18,904 Mod ✭✭✭✭slave1

    Re high power, there's nothing anywhere to state "high," rate AC charging in any way impacts battery life. I had a Model S which I AC charged at 22kW a lot for years and no impact on degradation

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  • Moderators, Home & Garden Moderators Posts: 5,995 Mod ✭✭✭✭graememk

    Without getting into too much of an essay here :P I do get where your coming from. If I had 3 phase in, Id keep it.

    Your gonna need someone with commercial experience though if you want a 3 phase inverter.

    And I agree people are getting lost with the generator, And as you said, is already paid off, its there.

    Most some options,

    Put solar on the house single phase. covers the house load, but with the generator switchover not sure how that would be handled... The generator will generate its own mini grid that the inverter can grid tie to.. or connected to a relay that disconnects the inverter if the generator is active. .. maybe id say currently 95% of your loads would be on that single phase anyway. - possibly the cheapest and simplest.

    Put a 3 phase inverter before the generator, so when grid goes out, inverter shuts off, generator takes over. Drawback is that you'll need a much more expensive 3 phase inverter, and still only using 1 phase of it - No experience of 3 phase inverters so cant say how they behave. Most likely whatever is on the other 2 phases are exported.

    As for relying on a feed in tariff, plan for 0c anything else is a bonus. Besides, if you get something in now, you can always upgrade/change in the future, Inverters and panels are very sellable second hand,

  • Moderators, Motoring & Transport Moderators Posts: 6,521 Mod ✭✭✭✭Irish Steve

    This is proving to be very useful, and worth while, and to make it even more helpful, I had a useful mail from a friend late yesterday that mentioned parallel inverters, and they can be used in single phase and 3 phase mode, so that opens up a whole range of possibilites, and they have options for generator connect as well.

    I have a very powerful UPS that I will probably sell on before too long, it needs 3 phase in because of the voltage, it's ancient, but a good make, single phase out, but capable of providing 16Kva, the down side being that it needs 23 12 V batteries. It came with a separate cabinet full of 150 Ah VRLA lead acid cells, but they were close to end of life, so got recycled, even back then nearly 2 tonne of lead batteries paid for the trip to collect it, so I've never commissioned it, the 2009 recession killed the project it was bought in for.

    The temptation is to try and find out if it could be used with LiFeP04 cells, as in that case, I could use it for the domestic supply, and not have to worry in the same way about solar inverters in the same way. If I could use multiple panels and MPPT units to charge the 23 x 12 v cells, that would be even better, but I don't have a technical manual for the UPS, as I'd need to be able to get at the charging circuits to make sure that it worked alongside the solar gear without hassles.

    It will all come together before too long, just a case of being very careful with the best way to get it right. And yes, I am very much aware of the precautions needed around high voltage DC systems, several years working with fork lift batteries was a very useful education.

    Shore, if it was easy, everybody would be doin it.😁