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Very much non standard Solar system

  • 30-04-2022 11:51pm
    Moderators, Motoring & Transport Moderators Posts: 6,517 Mod ✭✭✭✭

    So, as long as I have managed to get my head around all the technology buzz words, and not made any dangerous or even wrong assumptions, I am hoping to go down the Solar road later this year, as long as I can get a supplier to quote before the SEAI change the rules again.

    This is going to be a very non standard configuration, because I have some non standard equipment here already, and it makes sense to incorporate it into the total package, as it solves some issues going forward.

    So, let's see where this is going, and what others with more experience of this area think of it.

    I have a large roof, the southerly aspect is about 30 degrees east of south, a tile roof dormer, so steep enough to be good, the size is 20 metres x 7 metres, there is a line of velux windows, and a chimney in the middle that may cause some slight shading issues if I put up more than 2 rows of panels, but I'm hoping the chimney will become redundant and can be removed once we've sorted out a viable replacement for the oil boiler that is the main heat source at the moment. There are no shading issues for the lower section of the roof, so at least 18 panels in 2 rows is not an issue, and maybe more depending on the exact size.

    There are a number of non standard extras that are very much not normal domestic power items, they are a result of being involved with computers for a long time, and having to run a medium size mini computer in a dedicated computer room in the garage some 25 years ago, back when disc drives used stupid amounts of power (6Kw) to start them.

    That meant I had to get 3 phase power in, in order to be able to support the load, and I also ended up with a large standby generator that was put in to allow me to quote (and get) a contact to provide a backup system for a large payroll system, and I had to be able to operate even if the power was out in order to be able to meet the contract requirement, which resulted in a 35 Kva 3 phase standby generator that can pick the load up in less than a minute from automatic startup, and a 16 Kva uninteruptible single phase power supply, whick requires 3 phase input in order to generate the voltage required for the battery charging, the batteries are 312 volt DC. The UPS has not been in use for some years, as the VRLA batteries had reached the end of their useful life, and were scrapped as we didn't need the UPS in service at that time.

    The large computer is now long gone, and our usage is somewhere in the 5000 Kwh per annum at present, though I am expecting that to significantly change going forward, we've been using oil to heat hot water for years, and I am expecting that we will end up with a heat pump sooner than later, and at least one EV, so the usage will for sure increase significantly.

    I am going to have to get a survey done for a heat pump, just to keep the SEAI happy, and make sure we get the grant, but I am expecting the house to qualify, as we've had the necessary upgrades done over time that will result in an acceptable Heat loss indicator, it's already a C1 BER, and we've since had the roof insulated at rafter level, which made a huge difference as it's a dormer bungalow, and there's new doors and windows on the way, and I can take an existing fireplace and chimney out to improve things as well.

    We're on a Day Night tariff at the moment, which I don't see changing any time soon, as it seems that smart meters for 3 phase are some way down the list. We may have to go smart meter though in order to get the feed in tariff at the relevant rate for the higher load. 

    The thinking is a 3 phase inverter that can cope with around 20 Kva, with the intention being to be able to join the scheme that allows for more than 11 Kva feed in to the grid, and configure the system to have around 10 Kva of panels initially, with the option to add significantly more as funding permits, and an initial 5Kwh battery that can be charged off the Solar system, with the battery size also being increased over time, my eventual hope would be to run the heat pump off either solar or battery for most of the time, using night rate top up of the battery if needed during the low solar periods. I anticipate that the heat pump will be 3 phase, so not run through the UPS.

    The intention is to use the old UPS to feed the domestic load, (even allowing for the loss implicit in using that device) as that gives me the ability to avoid imbalanced loads on the inverter, the UPS requires 3 phase input, even though it's single phase out, but the UPS can support the entire domestic load with a good margin to spare, even if we add something like additional heating into the hot water system to supplement the exiating immersion heater. In the event of the grid dropping, the UPS will cover the time required for the generator to come on line, so no break for the domestic load. It looks like the Solar inverter will have to be shut down to prevent damage to the generator, though it may be possible to charge the solar batteries while the grid is down. That's going to depend on the make and model of inverter, and the ability to control it from the generator control panel will be a deciding factor, as the generator is fully automated start up and shut down.

    I also anticipate that there may well be additional inverter/s further down the road, so that more panels and a larger battery can be charged, but that will be dependent on seeing what our eventual load ends up as.

    I would love to be able to get off grid, but with the attitude that is very apparent from Ryan and his hangers on, the chances of being able to use oil or gas longer term is looking very unlikely, so we're all going to have to use electric power for everything, and I see it taking quite some time before the smart meter rates become attractive, so using solar to the maximum possible has to be the primary objective, with the best available night rate being used to top up the batteries if they are not getting enough from the Solar panels.

    So, that's the sort of direction I am seeing, and yes, it's not standard compared with most installs, but it should give us the flexibility that I'm hoping for, and hopefully allow us to have a reasonable system that meets our requirements without costing a fortune to run it.

    I am expecting to end up with something like home assistant running on an Intel CPU, I have an Intel NUC that can't run Win 11, so that looks like an ideal candidate for this task, and another machine has a touch screen, which should be ideal for monitor and controlling the various systems going forward.

    I suspect that there are not many, if any, users on here with anything like what I'm thinking of moving towards, but hopefully, the people with significant solar experience will be able to add something to the discussion. If you think I'm barking mad for considering this, then say so, I'm not going to get upset if that happens, I'm not going to pretend I know enough about Solar at this stage, but it seems to make sense to continue to use the other stuff I have here to make things easier.

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


  • Registered Users Posts: 6,164 ✭✭✭Ubbquittious

    How easy is the UPS to maintain? If something goes in it do you have to wait for some military surplus place in some forlorn part of America to ship you the expensive dusty proprietary part at a huge cost? Do you know every circuit of it inside-out? Will you have an easy changeover if it does pack up or go down for a few weeks?

    Its a nice idea, would be nice to see it when it's all goin

  • Moderators, Motoring & Transport Moderators Posts: 6,517 Mod ✭✭✭✭Irish Steve

    Well, the simple answer is that most of the UPS should be readily available as commercial parts, it's a commercial device rather than a military piece of kit, but it's one of the issues to be looked at very carefully. I've not yet tracked down a technical manual or circuit diagram for it, if I could, then the decision would be easier.

    If it fails, there's an instant change over switch that can be used to bypass the device, and put it in maintenance mode. so while it would mean that there's no backup as such, everything else would work, and it could be sorted out without (hopefully) too much pain.

    Having said that, since I posted the original post, I've had a link to a chinese supplier ( that might mean I can do what I want to without using the UPS, their inverters can be paralled to produce 3 phase and can run with a generator in the system, which could make it a lot easier to achieve the result I want, and not break the bank in the process, in that if I put in 4 x 6Kw inverters, I can run 6Kw of 3 phase heat pump, and still have 6Kw available on the house single phase, and that can all then be run, (including back up power) off the one (large!) set of batteries. If I want to, I could put another 6 Kw on the house single phase to allow me to run things like immersion heaters as a load shed device to use excess power and heat water in the summer months.

    I need to make sure that I've got it right, and that their inverters will run with AC from the generator, if they will, then life has become a LOT simpler, as it won't be a major issue to make sure that the panels are not feeding back into the generator if it has to take over if the grid is down. The other thing to make sure of is that if I want/need to, I can charge batteries at night on cheap rate to ensure a full start the following morning, which could be very relevant to running heat pump as cheaply as possible during winter months.

    Phase 1 is started, the Intel NUC is running Home assistant, it was easy in the end, and hopefully, I can get the Shelly 3EM working tomorrow, I will have to knock some of the existing system off line for a while to wire it in, but it won't affect the house single phase, once that's done, I will start seeing some grid usage figures that will help determine some sizings.

    Still lots of research to do to get this right, a lot of suppliers don't seem to be geared up to deal with this level of complexity and integration, if the lack of response to requests for quotes is anything to go by.

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

  • Registered Users Posts: 2,344 ✭✭✭bullit_dodger

    Must admit that I admire (and respect) the willingness to take this on as a project, but I just don't see there being an ROI on the whole 3x phase thing to go the way your intending. Yeah, everything you've mentioned is prices will rise, the grid will come under duress, but this isn't south africa. While it does feel like a 3rd world country at times, in reality......I can't see there being rolling brownouts, and if you have three phase or single phase, if the grid is down.....three phase ain't going to help you, other than increase the complexity

    Incorporating generators and UPS systems.....I think you can get it to work, but it's really (to me) a question of

    frequency of outage(s) x duration of outage(s) verses the cost in developing a system to counter that.

    Some of the lads here have 10Kwhr of batteries setup for €2-3K. As an alternative what about say 30-40Kwhr of a battery bank with a single phase inverter. The whole problem with 3x phase and what you are doing is that your very much a test pilot in the residential scheme of things. Yes, 100% there is no technical limitaiton stopping you from doing what you want to do, but you might be spending €20-30K to get a system working that may not be more performant than a more simplistic system. Is getting it to work for €30k a "win"? With a single phase system, it's also much more easier to get support. Many (residential) sparks won't touch 3x phase as they simply don't work with it regularly enough.

    I do get how you got where you are Steve. I'm old enough to remember the strikes and riots of the early 80's between Maggie and Scargil, and I certainly don't think your wrong at all, but I do think that I would have different thoughts/viewpoints on the way things will play out

    So I'm about ~12,000 units/year myself. No issues on a single phase, and I think going to 20,000 (possibly as much as 30,000) on a single phase is easily achievable. To me, it's not so much about the quantity, its more about the rate. Yeah, heat pumps and electric cars they will require power, but they tend to want power at times where the house isn't "busy". 2am, 3am in the morning etc is where you'll normally be charging the car, and you can do that at 7Kw easy enough with single phase. Many of us have Triton T90's showers in our house which are 9Kw. With the right cable guage.....totally doable. 

    Plug in your EV and 8 hrs @ 7Kwhr.....well that will fill (from empty) virtually every car out there. The question then is,

    "Is the cost worth the benefit?"

    as in being able to charge your care 2.5x -3.0x the rate and support for other heavy drains. If the EV is full at 1am, verses 6am.....where you are asleep in both that worth the cost? Naturally only you can answer those questions, but for me while I'd like you to get the 3 phase working.....I think your massively over complicating things.

    That said since you have 3 phase, I don't know if I'd get rid of it, hard to say only that complexity may not be worth it.

  • Moderators, Motoring & Transport Moderators Posts: 6,517 Mod ✭✭✭✭Irish Steve

    It's a very hard call, and I have to admit to being nervous about making the right choices, the biggest issue I see is that we're going to be faced with heat pump or nothing before too long, and what's also clear is that unlike oil, where it's possible to run for a few hours a day and then rely on slow heat loss from the house, heat pumps are going to be operating at some level for pretty much 24 hours a day, albeit at less than maximum power, because they don't have the same heat input capability as an oil boiler.

    A big heat pump can be drawing 5 or 6 Kw per hour, and yes, that can be then pushing 15 to 20 Kw into the house, but an oil boiler that's using a 1 (US) gallon per hour nozzle , 3.7 litres per hour is pushing nearly 40 Kw into the heating system, and yes, the burner on oil is not running all the time, and just as well, as it would get through nearly €5 per hour of oil if it was! The issue with a lot of the heat pumps is that they're operating at a much lower temperature differential, so without upsizing radiators to nearly double the size, there won't be sufficient heat output from the existing oil system radiators to acheive the desired temperature, unless it's running much longer hours, and that comes with a cost.

    Getting a good heat requirement figure is a nightmare, and the system to do it is being well manipulated by SEAI to look after their chosen elite installers, which is another big disincentive to going forward with any scheme.

    If Ryan and his cronies really want to see a significant reduction in CO2 emissions, they need to do things like remove VAT from energy efficient schemes, and do that for ALL users, not require the use of SEAI approved installers, as that's going to make it impossible for a lot of people to do anything in a sensible time scale.

    I digress.

    3 phase for heat pumps has an advantage, because the voltage is higher, the current needed is lower, which has big advantages if trying to run the thing off an inverter and batteries, and things like the start surge and the like are less, they don't need capacitors to start them, so there are also maintenance and reliabilty issues with 3 Phase that make them better than single phase for this type of application, and because the 3 phase is not loading the inverter as much, there's more capacity available to run other devices. That one fact alone will be a good reason to keep the 3 phase.

    Then there's the issue of what happens during the day even if you have a full battery but only a 5 Kw inverter. That can't run a 9Kw Triton, so you're into grid draw even if you've got a 30Kw battery, and the same sorts of issues can arise with doing things like using an electric hob/oven for cooking, and then sticking a 3Kw electric kettle on, that's another grid draw, which if we're trying to get off using daytime units, it's bad news, in that there's also the "background" load on the system from lights, fridges, freezers, TV and related devices, computers, and all the other modern detritus that is running 24/7. Even running a washing machine and dishwasher at the same time could be enough to go into grid draw, so it's not an easy equation to work out.

    What I don't know yet, because it's too soon to have a response from some of the suppliers, is the price for the hybrid inverters that can be paralleled, as that will possibly open up some very attractive options, and make it possible to get to a point of being able to use zero expensive day units, and a lot of cheaper night units, and I won't need the UPS at all, as they can be run without grid to control them, and also can be run with generator, so the best of all worlds.

    I may not enjoy some of the programming that will be needed in home assistant to get the batteries to charge at best rate if the generator is on, but that's not a day 1 requirement, that's just a bonus of having the generator running anyway, a bit like us remembering to stick the immersion on if we have a power cut to take advantage of the fact that the generator is running anyway.

    I'm very happy that I've had the experience I have of installing the generator and related systems, and done a lot of work on forklift batteries, in that both have provided valuable experience.

    What's for certain is that the next few months are not going to be boring!

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

  • Registered Users Posts: 2,344 ✭✭✭bullit_dodger

    I think you may have to relook at some math there. Sure a Heat pump could draw 5 or 6Kw per hour......but it won't be doing that all day long. There are many a boardsie here who have heat pump and EV and I'd reckon that a heatpump probably adds 4000-5000kwhr a year to the house consumption. I'd say 30-40Kwhr a day in winter for a heat pump sounds about right (I'm guessing). I'm sure someone who has one should be able to inform us.

    So with a standard house having 65A main fuse and running at 220, you'd have 12-13Kw on single phase to play with. Should be able to charge a car at 5Kw, run a heat pump at 5Kw and still have a bit left over to run the house at 2am.

    Totally (totally) get the advantages of 3 phase. Again, I'm not arguing against the 3 phase.....just the fact that your effectively a test pilot there with the level of complexity. Compare that to someone who has a "normal" single phase house....they might have a EV, heat pump and still be happy out? Can get suppliers to talk to.....I get the feeling that your already suffering there with the lack of info/response there. This is probably a symptom. Again, getting a 3x phase to work is perfectly doable, but it's a "level above" your bog standard install.

    Can I ask first though is your house appropriate for a heat pump? Airtightness, insulation, etc. Just wondering if your trying to solve a problem where you don't have a house which is a good fit to begin with. My own one I wanted a heat pump, I looked at the requirements and I just don't think with the losses I have (C2 BER rating) that I could get one in and have it "work" for me. So I scrapped the idea. It'll be some other heating system for me in 10 years. Possibly hydrogen or something if they ever get the dual fuel to work in the burner.

    Everyone has different value systems, but if it was me......I'd try to have single phase PV system with DIY battery. Sounds like you've more than enough competency to knock a DIY battery together. Or 2-3x of those Plyons i think can knock out current in parallel. I'd flog the gennie and UPS on eBay. Yeah, I know...but unless you regularly have power cuts....(do you?) How many times in the last 5 years have you needed to run it? DIY battery (should) cover you for enough hours for the power to come back on.

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  • Moderators, Motoring & Transport Moderators Posts: 6,517 Mod ✭✭✭✭Irish Steve

    All relevant, and cause for much reading and digging around all the relevant sites that have any useful information, but there's the rub, there are times when it's very hard to distinguish between good information and pure sales speak that has no substance in reality.

    Re the heat pump, the house here is 3500 sq Ft of dormer bungalow, 1990 construction, and we looked at Heat pump at the end of 2020 to replace the existing oil boiler, and there was a (not very good) BER done before we said yes, and in theory, at that time, we were hitting a BER of C1, (the cavities had already been filled) and it was decided that a heat pump wouldn't be a good move at that time, so since then, the roof has been spray foamed, which made a huge difference, as it killed the draughts through the roof that used to suck the heat out almost as fast as we put it in, and we've got new windows and doors on order that will change the heat losses there, and realistically, once that's complete, there's little else that can be done that will give any sort of sensible return, other than getting rid of an open fireplacce that has a gas fire in it. I'm in the process of getting the BER details to try and recalculate what it will be with the recent upgrades.

    After that the only other option would be demolishing the entire house and rebuilding to modern standards, though I have my doubts about the effectiveness of some of the modern ideas, so our options are limited, and that route is certainly not a viable option. I'm very much aware that if we put solar in, the BER would be improved, but the downside of that is the actual heat required to heat the house would not be changed in any way, so that's a very two edged sword, so I'm not about to get caught by that trap.

    I have wondered about the validity of things like wood pellet boilers, but I have grave doubts about the reliability of supply of the pellets, and the price, in that I'm not sure that there is manufacturing here in Ireland, and if they're having to be imported, that raises a whole list of questions about the long term future of that source. It's certainly not an option that seems to be getting much favour from people like SEAI, though I suspect that may be down to the relatively low cost of replacing oil with wood pellet, they will struggle to get many suppliers to go with that option because there's very little in it for them, I'm under no illusions, the present SEAI schemes are very much loaded in favour of the installers, and not doing very much to really speed up the process of going carbon free, but given the lacklustre performance of the people leading the process, that's no great surprise.

    In terms of the other issues, like generator usage, we've had a couple of longer outages of over 4 hours in recent times, the reason for keeping the generator was to ensure that if the ESB went down during bad weather, we still could run pumps that provided us essential flood protection, and hopefully, that scenario will finally end later this year when the OPW are supposedly finishing the scheme that's been ongoing for the last 6 years, having been scheduled to take less than 2 years! it's now so overdue for completion, I've given up trying to guess which year it is going to finish.

    In cost terms, even if it's not essential, the generator will stay, the annual cost is so low, it will probably cost me more to take it out of service than it will to keep it in use, and the comfort factor of knowing that if we get a real adverse dose of bad weather that we're able to keep pretty much everything going, that's the justification, after that, with how uncertain everything is, in one respect, the OPW delays have probably helped us, as we'd probably have moved from oil to gas if the works had finished on time, but now, I have to wonder about the viability of going gas, so maybe the delays have done us a favour in that respect.

    making the right decisions on this is not easy, I sometimes think our odds on a lottery win would actually be better.

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