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Would Solar be cost effective for me? We used almost 5MW last year also have an EV

  • 17-06-2019 10:40am
    #1
    Registered Users Posts: 1,118 ✭✭✭ reni10


    I am looking at Solar to help manage my electricity bill.

    Last year I used almost 5MW of electricity which includes charging an Electric Vehicle on night rate electricity.

    My home is a 4 bed detached 2 storey property with Gas central/water heating and we also run a fossil fuel inset stove in the winter to help heat the downstairs of the home.

    I currently have an energy monitor installed and it looks like when most things are switched off in the home we use less than 300w of electricity.

    So my question is what type of solar cost would I be looking at and would it actually make sense to do this or will it take 20-30 years to get the payback and therefore not worth it at all?


Comments

  • Registered Users Posts: 100 ✭✭ Coltrane


    Hi reni10
    Just seeing your question after posting a reply to something similar on another thread: https://www.boards.ie/vbulletin/showthread.php?p=110456353#post110456353.

    I've a similar setup to yours except that I've an electrical heating system (A2W).

    Even with that synergy, the 'payback' of my circa 5kWp PV array will be something like 30 years at current energy costs and last year's capital costs (of installing the PV).

    The point of my other post is that when calculating payback we need to factor tomorrow's costs - that we'll certainly face - of cleaning up the damage we're doing today to the environment: payback numbers with no assumption as to these costs are worse than wrong.

    How much will these costs be for you or me? No-one knows, but I think they will be very, very sizeable. Today's draft climate action plan should have some numbers for Ireland.

    Hope this makes sense.


  • Registered Users Posts: 1,118 ✭✭✭ reni10


    So a quote from one provider of about 8k for a 5.6kwh battery storage system after the grant is about the best I have seen.

    In total for 12 full months electricity usage of the neat 5Mw that the household used it came to €820.

    So even if I could replace 100% of my electric needs with Solar it would take me at least 10 years for the payback on that system!
    Realistically though only about 70% will be replaced with Solar so this would be a saving of approx €575 a year.

    Then the PSO levy will also still need to be paid so that is another €40 a year making the saving approx €535.

    There also would be some minimal savings on hot water heating but with the gas I use to heat the hot water only being about 5c a unit this is not much of a saving over the year.

    Now the real payback time is blown out to about 15 years!

    I know the price of electricity will probably go up in the future and there will probably be a FIT in the next few years but still you are looking at a considerable payback length.

    Would it be much better if I just went for panels only with no battery storage and tried to do as much of my heavy electrical use during daylight hours so instead of 70% of my usage being on solar it would drop down to 40%?

    So a quote of 3k for the panels only would mean I would be saving approx €300 a year and would mean the payback is back to about 10 years.

    Doing those figures it looks like for me the savings and payback are just not there yet until it becomes a lot cheaper to install the battery storage systems.

    Any comments from those more experienced?


  • Registered Users Posts: 32 ✭✭✭ bajj


    I'm no expert, but with battery storage you will also need to factor in the cost of replacing them every few years.


  • Registered Users Posts: 1,916 ✭✭✭ Reati


    reni10 wrote: »
    So even if I could replace 100% of my electric needs with Solar it would take me at least 10 years for the payback on that system!

    Stupid question and not at you OP directly but I always see this payback comment made like it's a bad thing and can't work my head around it.

    Surely even if takes ten years or 15 years it's still better than foregoing the system and paying at rising electricity prices for 15 years or am I missing something?


  • Registered Users Posts: 2,444 ✭✭✭ wexfordman2


    bajj wrote: »
    I'm no expert, but with battery storage you will also need to factor in the cost of replacing them every few years.
    Every few years?

    Look, while there is a genuine questions around the payback period of batteries, that's a bit of an exaggeration, the warranty on most batteries should see you get ten years out of them.

    With regards payback, personally.i think the issue is much more around getting a reasonable.price and not being ripped off, rather than actual payback.

    If you can break even after 10 years, then you are quid in, but I wonder how many people put payback into the equation when say, looking at buying a new car ?

    Affordability, and not getting ripped off, then performance, then payback would be my order.


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  • Registered Users Posts: 32 ✭✭✭ bajj


    By few, i mean 5 - 10 years, batteries are expensive and require care to ensure you get the optimum life out of them, I just think that this should be factored into the overall cost.


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    Some batteries (heavy duty,marine or for PVs) have a greater lifetime functionality than normal ones.

    However,these units have guaranteed best case 5,000 cycles which should cover 10 years ( 365 days cycles x 10 years = 3650 cycles at manufacturer specified SoC ) but in case of going damaged, the manufacturer will have access to logging function and quickly dismiss any warranty if you didnt use it as per their terms,which are in the small print...


  • Registered Users Posts: 1,118 ✭✭✭ reni10


    For me if I could get a suitable system installed for around 5k which would offset 70% of my electricity cost I would go for it now but it seems it is more like 9k so almost double...

    Anyone got a 5k quote for something like the above?


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    reni10 wrote: »
    For me if I could get a suitable system installed for around 5k which would offset 70% of my electricity cost I would go for it now but it seems it is more like 9k so almost double...

    Anyone got a 5k quote for something like the above?

    For around e5k,in regime DIY you may get things done alright .

    But more important is your usage habit...when sun is out there, you need to extract and use it at maxim, generated vs usage.
    Does it make sense ?

    Quotes you will find on the dedicated topic.


  • Registered Users Posts: 1,118 ✭✭✭ reni10


    Yeah I would maximise usage during the day and have timers on all appliances line dish washers, washing machines etc.

    I don't think I could do the DIY route though as I don't have the skills needed.

    What would be involved in buying the panels and the other bits needed and then ask an electrician to put it in?


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  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    reni10 wrote: »
    Yeah I would maximise usage during the day and have timers on all appliances line dish washers, washing machines etc.

    I don't think I could do the DIY route though as I don't have the skills needed.

    What would be involved in buying the panels and the other bits needed and then ask an electrician to put it in?

    Check the quote topic to see other people's price and system parameters.

    I did it complete DIY self learner and i can say is not easy but is very happy challenging.

    If DIY not doable,then you dont know what is needed to run and complete the project,no parts knowledge no installation time,steps,needs,requirements.

    Well...buying all the parts yourself and just engaging with labour and micromanaging the installation may save you a bit but not sure if your time "wasted" on that could be related to a cost of time and charge that can be recouped in other way(s) !?

    If you are buying all the parts then the installer loses on his mark up side of the quote / invoice.

    You will need a roofer to get the panels up the roof,with a mounting kit and rails. Easy if the roofer "thinks and wants" to do it. I will say it will cost you maxim €500 over a day or two,subject to time of the year (if roofer is busy he will throw you off with a big quote, if no busy might do it on the decent cash side) and the forecast of the weather(if raining,forget it,do you have to pay him ? i did i over three days due to rain).
    Then spark is easy but how do you know to connect the panels and how to get inverter installed ? A good electrician that knows his tuff may charge you a for a day to do it,thats another easy €3-500 on the invoice.

    Hmm, not sure... where are you based, how many panels can you up the roof,whats the house position / location as in a big picture !?

    Be good...


  • Closed Accounts Posts: 3,364 ✭✭✭ rolion


    Not lastly... just to let your imagination dreaming !

    Stretch the budget and go for a low setup of 8 panels x 300W = 2400W installed power,get a 4KW inverter future proof if mor epanel sneeds to be added later.
    Get a 2 x 20 solar (or even 1 x 30 ) tubes on the roof and you have the ideal soultion done and ready to harvest.

    You get grants for both of the above from SEAI.
    Good grants...


  • Registered Users Posts: 8,287 ✭✭✭ n97 mini


    reni10 wrote: »
    I currently have an energy monitor installed and it looks like when most things are switched off in the home we use less than 300w of electricity.

    Shortest payback is to cover the base load. 2 or 3 300w panels and a small inverter will come to less than €600 if you're frugal.


  • Registered Users Posts: 1,118 ✭✭✭ reni10


    Is that supplied and installed for 600?


  • Registered Users Posts: 407 ✭✭ phester28


    i was trying to do it this way but you will be very lucky to get anything for 600. 3 panels 150inc vat each so 460 inc vat. inverter Solis 1kw is 354inc vat. You need panel mounts. say a flat roof to ease a DIY install. Renusol console+ are 60 each so another 180 inc vat. 60 euro for a roll of solar wire, MC4 are cheap and you need isolators. your already at 1100 euro for a self install

    hard to skimp on any of the above. maybe a slightly cheaper micro grid 4 panel inverter for around 290. in which case you don't need a DC isolator or any safety disconnect (I think). The disconnect is only required if doing an SEAI install but it is a safety feature


  • Registered Users Posts: 8,287 ✭✭✭ n97 mini


    reni10 wrote: »
    Is that supplied and installed for 600?

    That depends :) I have 3 X 300w panels (bought brand new) and a brand new Solis 700w inverter I bought off eBay for around €150 delivered. Add in a few cables and connectors and the lot came to less than €600. The panels are lying flat on my shed roof.

    It's wired in to the spur that goes to the shed (that has nothing but a light on it) temporarily by me. I'll get my cousin or some other sparks to do the paperwork eventually.

    Currently the predicted payback is between 4 and 5 years.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,843 CMod ✭✭✭✭ unkel


    n97 mini wrote: »
    That depends :) I have 3 X 300w panels (bought brand new) and a brand new Solis 700w inverter I bought off eBay for around €150 delivered. Add in a few cables and connectors and the lot came to less than €600. The panels are lying flat on my shed roof.

    It's wired in to the spur that goes to the shed (that has nothing but a light on it) temporarily by me. I'll get my cousin or some other sparks to do the paperwork eventually.

    Currently the predicted payback is between 4 and 5 years.

    A bit optimistic? Just picking some guesses from thin air here, see what you think. I'm sure you've done same to come to your payback calc?

    Let's say your solis can produce 750W (a bit more than it's rated for), so your system is then really a 750kwp system but oversized so a bit more efficient. South facing, zero shadowing in Dublin area that would generate about 750kWh per year, flat facing, maybe 650kWh?

    Your base load is about 300W, so you will lose quite a bit of that to the grid. Perhaps about 40%? That leaves 390kWh that you use. As you posted yourself today, some of that is produced during night rate hours. It will be small though, I doubt more than 5%. Let's not deduct for that

    So your savings are then 390kWh * 18c day rate = €70 per year, payback of a €600 system about 9 years

    But there are upsides as well. I started with a very similar system to yourself. Bought 3 brand new panels and a second hand inverter. I bought well and installed on my shed DIY. I sold the panels and inverter a year later for more than I paid for them + what it cost me in cables, disconnect, mounting materials

    So my system didn't have any payback time at all :)

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 8,287 ✭✭✭ n97 mini


    It's early days yet, so I can only go on the data I have so far. No doubt winter won't be nearly as productive.

    Like yourself I will probably uprate once I get battery storage figured out and I expect when the time comes I'll be able to sell my inverter for what I paid for it.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,843 CMod ✭✭✭✭ unkel


    n97 mini wrote: »
    It's early days yet, so I can only go on the data I have so far. No doubt winter won't be nearly as productive.

    Like yourself I will probably uprate once I get battery storage figured out and I expect when the time comes I'll be able to sell my inverter for what I paid for it.


    Sure, if you buy well, you could very well end up not selling at a loss :D

    But what way did you come to your calculation of the pay back period?

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 8,287 ✭✭✭ n97 mini


    unkel wrote: »
    Sure, if you buy well, you could very well end up not selling at a loss :D

    But what way did you come to your calculation of the pay back period?

    60kw/h per month @ 19c each = €136 per year. We're currently generating around 80 per month so I'm allowing for 25% to be exported.

    I'm expecting in winter the generated amount will be lower but the export will be closer to 0% too.


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