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My solar savings have peaked - I Think !

  • 24-01-2023 8:52am
    Registered Users Posts: 1,409 ✭✭✭

    I have been looking at my recent bill this morning and as this is over the two bleakest months, I think that I have done well and everything should be better from here until next November.

    Actual Electric Ireland Bill   


    Credit Amounts:

    ·        FIT €381.11

    ·        Government Credit €200.00

    ·        Electric Ireland Credit €50.00

    The bill should have been:

    ·         €765.74

    Other Savings not included in bill (Figures are approximate below 10% saving then plus 9% vat- Meh)

    Generated 602Kwh of Solar: @€0.42 = €252.84 savings

    Battery charges and discharged approx. 15Kwh daily over 64 days, 960Kwh saved @ €0.21 €201.60

    If I had no solar, no batteries or free credit the bill should be:

    €765.74 + €252.84 + €201.60 = €1,220.18 Which I am delighted about 😊

    We cant seem to reduce electr

    icity usage any more – Dishwasher and washing machine goes on at 6am

    I can’t see any other savings to be got in batteries as I used only 245 units by day and this was probably the days that the extra load of washing went on or the oven was flat out or just a full house over Christmas

    Have 6Kw inverter, 8Kw Solar Panels & 20Kwh battery pack

    So what else can I do I wonder, Is there any more of a return to be got in investing more in solar ?



  • Registered Users Posts: 18,254 ✭✭✭✭kippy

    How big is your house? What type of heating are you using? How many people live in the house?

    That is a massive electricity bill (€1220) if your figures are accurate!

  • Registered Users Posts: 1,229 ✭✭✭Galego

    That's pretty good! Excellent!

    Few notes for you if you are keen on cracking up the numbers a bit more.

    Are you sure 960Kwh went in and out of the battery? That'd mean 100% efficiency in between inverter/battery/cables/AC/DC/AC which in reality is more around 80-90%

    602Kwh of Solar. Is that all entirely self-used through house loads or went through battery some of it? Again if through battery then there'd be some losses.

    They may not get at all about the answers to the above questions but thought i'd ask in case you want to get a more accruate savings amout.

  • Registered Users Posts: 10,378 ✭✭✭✭the_amazing_raisin

    You'd be horrified at my bills then, I estimate without solar, batteries or government credits I'd be paying ~€3,500 per year when my discount expires in May

    Thankfully the solar is getting installed next month, and the battery will be ordered soon after 😁

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

  • Registered Users Posts: 21,010 ✭✭✭✭ELM327

    You have the same setup as I currently have. 8kWp, 6kW,20kWh.

    My account is in credit. There's always more savings to be had. For one, you're on the wrong tariff, with the wrong company. Secondly, you're using too many day units. You used 245 day and 2445 night. In my last bill I used 40 odd day units and 1800 night. I had 1.5 EVs for that bill period (sold our second car half way through).

    Changes you could make for more savings would be to reduce those day units. You have 20kWh of storage, if that's not enough for your day units then get more storage. I would also evaluate your usage in general, as we have a 6 bed house with 2 attached offices, two techs working from home full time with all the coffee machines the shop had, gaming laptops, consoles etc. We have some electric rads to supplement/reduce oil use. Yet my bill in terms of units is 2/3 of yours.

    I see what you're saying about diminishing returns. But I'm not at that point yet, I'm still using 1kWh per day of day units. You are using 4kWh of day units on average and that's way too much to say youre done.

  • Moderators, Sports Moderators Posts: 18,472 Mod ✭✭✭✭slave1

    Your bill needs to be based off the cheapest provider out there as else you are overstating your numbers, a few minutes on Energia's website would provide these numbers.

    You have 20% losses on battery in/out, items like dishwasher, washing machine, dryer need to be factored at night rate as this is when they should be used.

    I'm not sure if you are charging the battery at night rate, again if so you will not be saving full day rate, you will be saving the difference between day rate and night rate less 20%.

    You're 602kWh generation is exceptional for the last two months, the 20kWh pack is super (likely 16kWh usable) to take you off day rates

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  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    @kippy 3500sq ft on three floors is the house size and we use oil central heating, 5 live in the house and there is always someone home, have an EV also and this is responsible for 1400Kwh of the total.

    @Galego The numbers are there or there abouts, appreciate that there are always losses but its within 10% of it, enough for a general idea

    @ELM327 Stuck on that tariff for another 10 months I reckons so that cant change.

    @slave1 Energia has a clause if I use over 2000Kwh per month the night rate goes up an extra 15c, so I dunno about that now Price Plans - Energia

  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    I suppose the question still really is:

    Can I do anymore with the solar that would be worth the investment ?

  • Registered Users Posts: 10,378 ✭✭✭✭the_amazing_raisin

    More panels? Can't see more capacity ever failing to pay off, especially when we all get moved to smart meters and measured export

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

  • Registered Users Posts: 64,330 ✭✭✭✭unkel

    @Big Lar - "Dishwasher and washing machine goes on at 6am"

    Be careful with that, some of them on ECO programs take longer than 2 hours, so you would either be using peak rates for that, or eat into your battery unnecessarily

    @Big Lar - "Stuck on that tariff for another 10 months I reckons so that cant change."

    Of course you can change at any time. Costs just €50 penalty for breaking contract. Done it myself. Your night rate is insanely expensive and with your very heavy use, that penalty is paid back in no time with cheaper units from Energia EV plan

    For any of your calculations, you should only ever use the cheapest rate in the market. Also for PV production, you should only use the peak rate to calculate the value, for the units that you actually use at peak rate and could not use at night rate (this in practice is very little as most stuff can run on night rate / battery), so your calculated revenue / savings are inflated. Don't want to be a spoil sport here, but we need to properly assess our investments in renewables, not make the figures look nice, we are not out to be kidding anyone

  • Registered Users Posts: 21,010 ✭✭✭✭ELM327

    Yes. You're using too much electricity in total, an dyour day use is too high, and as I outlined above you're on the wrong tariff.

    Check what is using all the power. Pay the 50 quid break fee and move to Energia.

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  • Registered Users Posts: 21,010 ✭✭✭✭ELM327

    No point wasting money on panels, when there's so much he can do without any investment.

  • Registered Users Posts: 18,254 ✭✭✭✭kippy

    The OPs estimate was for two months only.

    3500 a year is about a grand a year more than my own usage. So not out of the ordinary depending on what you are using it for, size of house etc.

    Have a relatively small 1600 sqft detached house. 2 adults and 3 kids. No one at home during the day. No elec car and oil heating which I'd spent 700 to 1000 a year on.

  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    I know exactly whats using all the power but thats the way that it is

    • Have office with two PC'c, two laser printers,scanners and then there is a 24port POE switch with cameras and what not, and router and a 2nd switch with two small servers and all that's around 750w
    • Easy to make up the rest of it

    About moving to Energia

    Please see below if you use more than 3,000kWh day usage & 2,000 kWh night usage every two months, you will be charged the rates below for only those units above that usage. Applicable discounts will be applied to these rates.

    Now have second EV and expect night usage to be well over the 2,000Kwh bi monthly going forward so I am going to penalized an extra 13c a unit so I dont know if it will be really worth it

  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    OK, Just signed up with Energia.

    See how that goes

  • Registered Users Posts: 1,341 ✭✭✭Nelbert

    Based on your bill 2000 of those night units could be a good bit cheaper, 668 more than you are paying....

    You'd probably still save with Energia.

    I sympathise with the high usage (NAS, 48 port switch and a few other things beyond the norm myself). My background usage is 400w

    I've made a concerted effort to consolidate on the IT side (most of my stuff suitable to run as docker containers on the NAS). It's worth seeing if it's possible.

  • Registered Users Posts: 1,369 ✭✭✭DC999

    As a comparision, our house uses under 3000kWh a year (excluding heating + cooking + EV charging). Certainly not trying to gloat as I know we're lower than most. 2 adults, 2 young kids. I'm WFH fulltime but that's 100w max. We turn stuff off when not using it. So you could turn off the printers and scanners until you needed them. I’ve some plugs that let’s you pick how long to turn it on for. Press once for 15mins, twice for 30mins …up to 8 hours. So could turn on the printer that way and it auto turns off after 15mins. Or could get a smart plug and tell Alexa to turn it on or off. Or just manually turn off and on when needed of course 😊

    We’re close to 50cent for daytime units of electricity now for those out of contract. I’m damned if I’m giving that money away for free. There’s more our family could do with it.

    Your home office baseload of 750w. And in winter that’s all good as it’s all providing heat. But could the warmer months, you’re paying for that power to turn into heat. As a comparision that’s heating our 5 x 5m meter sitting room / kitchen at the moment with an electric rad. 

  • Registered Users Posts: 64,330 ✭✭✭✭unkel

    @Big Lar - the penalty rate with energia is only for the units above 2000 per billing cycle. I do go over sometimes too, but not by an awful lot. So only a few units are the higher rate. Still only half of peak rate mind. The overwhelming majority are still at the cheapest night rate in the market (Energia EV plan). Glad you joined them, we should all always vote with our feet!

  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    Would you believe that I updated the printers from HP3800's to Brother HL-L9310CDW's over the past two years and am actually shocked that there is no physical off switch on the brothers, fair enough they only use 10w in sleep mode but like for both printers that almost 0.5Kwh per day just to sit there. You would think in these modern times that the brother lads would have a switch in them.

    In the end of the day for the comfort of being able to run a business and work from home a constant load of 750w for office equipment is very acceptable.

  • Registered Users Posts: 10,378 ✭✭✭✭the_amazing_raisin

    Oh yeah I missed that bit

    We've two EVs in our house plus heat pump and electric cooking, and always someone working from home

    Last year's usage was 10,500kWh, roughly 45% at night rate

    Although to be fair that's the entirety of my energy costs. If you factor the same in for petrol and oil or gas I'm still saving some money

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

  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    Be interesting to see how things will go as we have a second EV here in the house now, but hopefully as it will be at home most days it will get charged from the solar in the coming months.

    Nov to Jan next year may be tough alright

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  • Registered Users Posts: 64,330 ✭✭✭✭unkel

    Aye. Dreading my renewal in late August already but as you say, all of us with big PV setups and batteries won't feel the pain until next winter

  • Moderators, Home & Garden Moderators Posts: 5,512 Mod ✭✭✭✭graememk

    Same boat,

    Most recent bill was about 380, (not inc any gov grants)

    70odd day, 2880 night!

    Although that was the darkest months, with the high electric demand, and heating on night rate, even paying the 880 units at the high rate it was still cheaper than oil.

    Once march hits, gonna be practically off grid.

  • Registered Users Posts: 5,419 ✭✭✭creedp

    I know when people invest in solar, drawing from the grid can be considered the ultimate no no. However, another way of looking at it is that if this excess over generation is predominantly driven by EV charging, then unless you spent big to purchase the EVs purely to save on running costs, you are making big savings all year around compared to what you would be spending driving 2 ICEs. So in other words electricity, even if drawn from grid, is a really cheap way to run a car and if you were still driving ICEs, next Nov to Jan would be that bit tougher. So IMO focus on how much better a position you are now in having installed the solar.

  • Registered Users Posts: 1,369 ✭✭✭DC999

  • Registered Users Posts: 64,330 ✭✭✭✭unkel

    I spent nearly €50 per week in petrol alone in my last main ICE car 7 years ago. That was nearly €2500 per year. Of course my electricity bill is several hundred a year more because of my EVs, but that massive petrol bill has disappeared!

    And even a gas-guzzling hard driven Tesla Model S, averaging maybe 21kWh / 100km, driven 20k km per year (substantially more than an Irish average car does), using over 4MWh per year (substantially more than an average Irish house uses - not for heating), this only costs €300 per year in electricity based on my 7.9c / kWh night rate

  • Registered Users Posts: 5,419 ✭✭✭creedp

    Exactly my point, if you can afford to buy an EV they cost pittance to run compared to an ICE. So instead of worrying about the cost of charging one people should be celebrating the massive savings and that's even without having free solar energy. My only regret is not owning one with a decent range!

  • Registered Users Posts: 64,330 ✭✭✭✭unkel

    Funny you mention "if you can afford"

    Before I bought my brand new Hyundai Ioniq 28kWh over 6 years ago, I did some sums. They showed that the total cost of ownership of buying a brand new car (with in hindsight overly prudent assumptions about depreciation) was lower than keeping the old petrol banger. I had the money in the bank, not making any interest, but even if you had to take a loan out to buy the car, the figures would have been close.

    This of course goes against all logic you were ever told by the man in the pub 😂

  • Registered Users Posts: 1,409 ✭✭✭Big Lar

    Great savings in owning an EV, the only problem is that you must pay up front for everything and get there savings bank over a few years.

  • Registered Users Posts: 1,150 ✭✭✭monseiur

    Hi Big Lar I'm contemplating a major re furb. on a 1950's bungalow to include solar panels etc. (Cheapest quote €78k. after all grants ! ) Can I ask what, in your opinion, is the approx pay back time on solar panels complete with batteries etc. ? I have been told it's 10 to 12 years depending of course on many variables. Will have to keep oil central heating as engineer reckons air to water is not feasible.


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  • Registered Users Posts: 64,330 ✭✭✭✭unkel

    How long is a piece of string? Depends totally on the size of your setup, your electricity consumption patterns, your electricity rates, how good a deal you got, etc.

    FWIW I did the (conservative) sums for a friend with a recent almost €10k (after subsidy) install of a 6kwp system with 5kWh battery, family of 4 with EV and it was under 5 years, that said he is on a smart meter and smart tariff and his peak rate is about €0.50 / kWh

    My own last DIY major upgrade (no extra battery) with very well bought parts had a payback time of not much more than 1 year (heavy electricity user)