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How Low Can You Go? (Limbo Dancing for PV Owners)

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  • 10-04-2023 7:56am
    #1
    Registered Users Posts: 290 ✭✭


    A new challenge thread? A way to convince the ditherers to go PV?

    Rather than how much solar, how little grid whilst still being on the grid...

    Here is our ESB Networks chart since the beginning of the month...

    Our meter (of the smart variety) has not moved this month. Thanks to a firmware upgrade on our KStar BluE-S 5000D hybrid inverter, which was importing 1KWh per day (previous firmware was battery averse at night) and has since peaked at 80W once last week.

    14 euros banked in export. Still over 700 in credit, which we'll soak up with additional heating/automated ventilation for next winter.

    We are not off-grid, just a frugal pair, living in a bungalow. No EV, yet and no fish tanks. The house is 100% electric save for a wood stove heating the living room, which I'd like to get rid of for my lungs. Desiccant dehumidifiers and a fan heater elsewhere. House tended to by Home Assistant. 5KW battery.



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Comments

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


    I do have a lot of pv and batteries,

    Also day is night and night is day (works better for the monitoring) when night rate is 23-8



  • Moderators, Sports Moderators Posts: 18,783 Mod ✭✭✭✭slave1


    Just not possible for me with two EVs to keep on the road, other than that I'd be just micro grid imports throughout the April - Sept period

    My stuff for sale on Adverts inc. outdoor furniture, roof box and EDDI

    My Active Ads (adverts.ie)



  • Registered Users Posts: 10,969 ✭✭✭✭the_amazing_raisin


    I might join in once I've got a battery installed, but in the meantime I haven't had to charge my car from the grid in 3 weeks 😁

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost



  • Registered Users Posts: 290 ✭✭JayBee66


    I'm sure we can have categories; EV owners and non-EV owners, HP owners and non-owners, battery yes/no and cave dwellers (like me).



  • Registered Users Posts: 4,428 ✭✭✭Gerry


    I'd say that just being aware of energy usage has saved for us, somewhere between 25% and 50% of electricity usage, whether a lot of this comes from pv or not.



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  • Registered Users Posts: 3,170 ✭✭✭irishchris


    Average actually slightly higher this week as since late Feb average is about 100 watts a day.

    No ev and decent storage/solar setup



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


    Is that real data from your esb meter?

    Those numbers don't look right (unless you got a perfect inverter) because all inverters realistically pull some trickle from the grid to ensure they are not exporting.

    My solis did it, and so does the sunsynk, now it is anywhere from 0.2 - 0.6 kwh which is maybe up to 10-15khw a month but it is p*****g me off greatly if I'm being honest since to me that's quite high.

    Only does it during gen hours not when running from batteries.



  • Registered Users Posts: 552 ✭✭✭idc


    Without a smart meter ESBN just report your actual/estimated/user readings on the website! but using my own monthly record of my meter (not perfect either as i don't record at exactly midnight on the last day of the month!!)

    Day rate I average 0.3 kWh a day for nov-jan, feb-mar average is 0.1 kWh a day

    Night rate (EV 41 kWh battery typically local trips and 10kWh home battery - filled winter to 95% and reduces per month from march) average per day for nov 17 kWh, dec/jan 19kWh, feb 11 and march 10.



  • Registered Users Posts: 3,170 ✭✭✭irishchris


    Yes accurate reading straight from smart meter. Also within 10 watts of what my sofar reports as import.

    Reason I went for the sofar over the sunsynk as the sunsynk 5.5 I fitted for family member has daily import anywhere from 0.5- 0.95kw and this is after me bringing it down with the adjustments to CT on the sunsynk. In fairness even the solis used to be about 250-500w trickle from grid throughout day and with battery balancing.

    Here is today's smart meter reading for yesterday's usage from grid. Often is only 80-90w but with herself baking yesterday evening and hob, oven, mixer etc it trickled more with battery draw on/off a lot during that time.




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


    Yeah it is up to the inverter I guess, they all claim 20ms response times but I call major BS on that, if that was the case then the below would not happen.

    The induction hob "trickles" a lot as it quickly "turns on and off" while cooking and the inverter takes a split second to see the draw when it changes.

    But the sunsynk at least sees all of this import whereas the solis was always seeing 0kwh import.

    Maybe I need to mess with the CT ratio see if I can lower the constant grid usage, which is set to 1w but it does pull anywhere from 10-50w when generating. Sunsynk said that's normal but ofc they would say that.

    The fix is to disconnect the grid ofc but I don't have the backup port powering my whole house, yet.



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  • Registered Users Posts: 290 ✭✭JayBee66


    Until it got a firmware update, last week, my inverter was pulling 1KW a night to do whatever it needed to do with regards to synching with the grid etc. Now, it appears to be using the battery for that task more so than the grid. Even at night there is about 500W of export, in addition to another 500W of battery for the inverter to run itself. There's very little going on in the house; the burglar alarm, fibre modem, router and home assistant. Everything else is off but 1KW is still leaving the battery.

    Post edited by JayBee66 on


  • Registered Users Posts: 1,080 ✭✭✭silver_sky


    Around 0.5-0.8kWh per day. That's ignoring the EV.

    Here's the month so far incl the EV charging




  • Moderators, Arts Moderators, Recreation & Hobbies Moderators Posts: 10,596 Mod ✭✭✭✭Hellrazer


    Serious question - how in gods name do some of you keep your imported usage so low?

    Genuinely do you not shower, cook, use lights etc?

    Im importing around 3-5kw a day - household with 3 adults and 3 teenagers - everything is off at the mains switches. Base load is around 150-250 watts and even less over night at around 100w and I still import the same amount.

    I just cant get my head around how some of you are doing it.



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


    Lots of solar and a big battery, well for me anyway



  • Registered Users Posts: 3,170 ✭✭✭irishchris


    Yes same here. Big battery and good amount of solar. Inverter makes decent difference too if can maintain as little import needed



  • Registered Users Posts: 1,080 ✭✭✭silver_sky


    My base load is much the same as yours. Shower is pumped from the hot water tank, only uses 500W for the pump when on. Tank heated by combination of Eddi & gas central heating. I've a 5kWh battery which helps cover peaks and avoid a lot of import but it doesn't catch everything.

    In terms of cooking earlier it was mostly off the battery earlier, but during better days it could be off the solar PV mostly. The system is south west facing so generation goes late into evening/night in summer. It could be 3kW at dinner time in summer.



  • Registered Users Posts: 290 ✭✭JayBee66


    A serious and good question. We need to add how many people are in the house to better judge each other's usage profile. We only have two in ours and both of us are committed to the cause.

    Some tips...

    We use an electric shower on the lower temperature setting and we only use it when we need water i.e. we wet our hair, turn off the shower, lather up with shampoo, turn back on the shower to remove the shampoo. Wet our body, lather up with soap, turn on the shower to remove the soap.

    One day, "She Who Must Be Obeyed" had a shower under dark skies and I had one straight after when the Sun had come out. She used 200W from the grid and I used nothing. The Sun and battery provided for my shower. She needed some grid to help. Keeping an eye on the Sun helps when using higher power devices. i.e. devices that provide heat.

    An inverter and battery is rated to provide only so much power. If you can assist it with sunlight then so much the better.

    We cook sequentially. Roast a chicken and bake anything we can, alongside. When the oven is done then we use the hob to boil vegetables. The microwave is used when the hob and oven are off. We cook in bulk on one day and heat up meals on succeeding days with the more efficient microwave.

    We don't have two or more high power devices on at once. Direct sunshine gives us some leeway on that rule. The immersion doesn't go on if we are cooking. We turn the immersion off if we want to boil the kettle. We swapped our 3KW kettle for the largest 1KW camping kettle and only put in the amount of water required.

    We keep an eye on the Sun. Not religiously. But it helps.

    We have Solcast running on our Home Assistant, which provides us with a profile for the day's sunshine. Of course, trying to use high power devices close to midday is best but Solcast can warn of sudden dips in the day for when you were planning to shower or cook.

    It's a game. Some play it and some just want to carry on with their lives as they did before. The latter strategy has its price.



  • Moderators, Arts Moderators, Recreation & Hobbies Moderators Posts: 10,596 Mod ✭✭✭✭Hellrazer


    Its interesting to hear peoples lifestyle adjustments to saving energy.

    While we have made some big steps I doubt that 3 teenagers have the commitment to make such drastic changes to their lifestyles.

    In saying that the changes we have made have saved us €200 plus off the last bill. It came in at 450 for 2 months - pre solar it was €650.00

    I generated 230 units a month and exported around 120 for both months.

    460 X .443 = 203.78 that I didnt buy from the grid. Bill could have been €650 plus.

    Had I been signed up for FIT that would have been an extra €24 euros.

    Next door - similar house size, same number of teenagers and adults - their bill was €850.00 for the last cycle.

    Changes planned are to put in a mixer tap and use the Eddi generated hot water for showering rather than the electric shower.

    Cooking Im going to find very hard to cut back on as we both work different times / kids come in from school at different times etc. I need to find a more efficient cooker. -anyone care to recommend an energy efficient one?

    Ive switched all the lights to LED less than 2w most of them. Im going to look at a 1kw kettle.

    Pre-solar my overnight usage 11.00pm to 7.00am was around 2-3 kw. Everything was left on standby. Now its less than .7 kw


    Small steps but Im making progress.



  • Registered Users Posts: 2,459 ✭✭✭bullit_dodger


    We use an electric shower on the lower temperature setting and we only use it when we need water i.e. we wet our hair, turn off the shower, lather up with shampoo, turn back on the shower to remove the shampoo. Wet our body, lather up with soap, turn on the shower to remove the soap.

    That's too much trucking for me to save a few 100wh at most....but be careful doing that. The problem is around how many of these electric showers work. If you are running the unit, it's taking in cold water (usually gravity fed from the tank in the attic) and it heats the water to say 45C and it flows out the shower rose, all good!

    Now what happens is that when you turn it off there's a little tank inside the Triton/Mira unit which holds about 500ml. The water in this tank is now at 45C instead of the usual 15-20C that it was taking it in at. So when you turn it back on, it's now heating the (already warm) water and there's a good chance that you can get 1-2 seconds of scaling hot water at 60C+ before either the safety thermostat kills the power, or the flow of cold water into the heater stabilizes the temp back to 40-45c or whatever you had it set to.



  • Registered Users Posts: 2,459 ✭✭✭bullit_dodger


    Im going to look at a 1kw kettle.

    Why? It's not the size of the power draw of the kettle which is the issue, it's the amount of water. Having a 1kw kettle will use exactly the same power to boil as will a 2.8Kw....other than it will take longer running. In fact there's an argument that the 2.8kw will take less power as if you have heat losses when it's running, so running it shorter will use slightly less.

    I guess if you were limited by battery draw down (3.6Kw or so) then a lower wattage kettle could be advantageous, but i think the most efficient way to boil a cuppa is a microwave. You basically only heat the water you need and once you figure out the temp you want = <some time> you will get it right every time. Most microwaves are in about 1000-1200w too.



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  • Registered Users Posts: 290 ✭✭JayBee66


    I habitually move the shower head over when lathering up but yes, I do watch out for scalding. When we get the heat pump then we'll replace the electric shower with a power shower and a false wall to bring in the hot water pipe.



  • Registered Users Posts: 290 ✭✭JayBee66


    I forgot to mention why we moved to a 1KW kettle and that was because we can use something else at the same time whilst keeping below 5KW. Above that and the inverter pulls from the grid. In the summer, I imagine we could go back to the larger kettle but for two of us, it's more than enough.



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


    The trick is big storage 20kwh+, inverter that can sustain 8kw to/from batteries, charge at night when the next day prediction is poor, no electric shower or immersion (combi boiler for the win)



  • Registered Users Posts: 2,459 ✭✭✭bullit_dodger


    I'd be fairly hard core about minimizing usage, but that's too much trucking for me. Go Microwave. its the most efficient as with the kettle and you boil it for 2 cups, you'll still probably have half a cup of water left covering the element in the kettle which you've heated. Microwave you only heat the exact water. Not sure on the efficiency conversion factor of electricity->microwaves->water, but would imagine it's pretty high, albeit not the 99% that a element in a kettle has.

    The things which really make a difference are the lights. Each sitting on the roof sucking 40-60 watts (or more). Swapping them to LED's is the biggest winner most folks will feel. Phillips Hue (which expensive) are pretty solid. Have them auto turning off when sunrise etc is good for ones you might want to leave on in the hallway/landing too.



  • Registered Users Posts: 8,483 ✭✭✭micks_address


    With us its not about avoiding grid import - the biggest change has been importing at night with as little as possible during the day. I dont expect the kids or my wife to shower after 11pm or before 7am on the cheapest rates.. even on the second setting the shower uses about 5.5kw.. its fine they shower for 5/10 minutes, most is covered from the 3.6kw the battery can provide via the inverter and they use a bit from the grid.. same often happens when cooking, will have the oven on, then the induction hob has 3 things on it, the toaster might get a go and the kettle boiled.. we are on a smart tarrif so we charge the battery to full every night from 2am and put on the dishwasher and ill top up the car if needs be. might also have a clothes wash set to come on.. lights make very little difference if they are led.. by far the biggest users in our house are shower, kettle, drier, oven, dishwasher, washing machine.. we have a projector we use for movie watching/gaming and thats fairly hungry as well.. our Oled tv can use up to 180 watts which is more than id like but its the price of the picture quality i like.. thats been the biggest change for us since going solar.. we know the exact energy consumption of everything!



  • Registered Users Posts: 8,483 ✭✭✭micks_address


    we have a kettle thats rated at 3.2kw and ive thought about getting a 2.2 one.. but with a smart plug energy monitoring current one only seems to use about 2.4.. its a smart kettle which cost a fair bit so i don't exactly want to dump it.. we have enough headroom to cover it now anyway with the newer inverter we had fitted last month.. can pull/push 3.6 to and from the battery... the price of a new kettle would cover any spikes we see.. a lower power kettle uses the same energy to boil... just takes longer..



  • Registered Users Posts: 1,414 ✭✭✭DC999


    Yeah, if you paid 60 quid for a 3kW kettle recently (pulling a figure from the sky), and downgrade to a 1kW one there is a cost to recover. Deffo makes sense to look at these things when next replacing.

    I'd be somewhat close to JayBee in terms of use the least amount possible (though not as lean as they are) but that's too hard core for others in our house. So I manage the parts I can and not worth a fight over the small stuff. In terms of electricity costs, it's only 1of X bills so I do what I can. I schedule all the stuff to come on at night (EV, dishwasher, tumble dryer when rarely used...).With Alexa I can tell it to turn off smart plugs for X mins while the shower runs. No one else is in the house would bother, but easy for me to do so why not. A 1kW kettle wouldn't be accepted by others in our house.

    As others have said here, I've learned much more about our usage since I got stats from solar. I assumed we used electricity fairly uniformly over the year. Boy, was I wrong! Even pre solar it would have been very low in summer and then curved up in autumn, winter and curved down in spring. I always knew our yearly usage (only 2800kWh for the house, 2 adults 2 kids but ex cooking and heating and EV). But never knew when we used that power (by day, week, month, year)



  • Moderators, Arts Moderators, Recreation & Hobbies Moderators Posts: 10,596 Mod ✭✭✭✭Hellrazer


    Based on a lot of experience it seems I need a battery!!!

    And more panels!!



  • Registered Users Posts: 8,483 ✭✭✭micks_address


    For us the battery helps us a lot in terms of load shifting to night rates. Don't think we'd see as substantial savings with just solar but then batteries aint cheap!



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  • Registered Users Posts: 2,459 ✭✭✭bullit_dodger


    Before FIT complicated the issue, I tracked (and still track) how much I save with my 8.2Kwh battery. It varies a little from month to month, but it's about €40/month for the savings related purely to the battery. I do however fully exhaust the battery virtually everyday. If you don't fully cycle the battery you can expect lower savings of course - as well as the fact that savings are very tied to the tariffs that your on.



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