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How many solar panels to buy if not getting storage batteries ?

  • 27-04-2023 3:26pm
    Registered Users Posts: 20

    I am starting of looking at getting Solar Panels

    I have a 3 bed semi house with 2 adults and 2 teens. Our usage last year was 4500 kwhrs. I dont have an electric car. 

    I dont plan to get batteries due to the cost

    I plan to get an immersion diverter. We currently use the gas central heating to heat the hot water tank in the winter. In the summer, its a bit of a problem. We dont have a separate zone for heating the hot water tank so we either have to turn on the central heating (after turning off all the rads), use the immersion, or have electric showers. I like the idea of using Solar Panels to have hot water on tap in summer like we have in winter.

    The first installer I spoke to said that 7-8 panels was sufficient for my needs. (Provide electricity during the day and weekends for ongoing running costs, provide hot water, use the grid for when Solar PVs are not generating sufficient electricity to fulfill my usage, potentially sell back any excess to ESB during summer months). So the panels would be reducing my bill and providing hot water rather than getting rid of it entirely.

    The second installer was trying to push me to buy 10-12 panels. However, as I'm not buying batteries for storage does this seem like overkill, would the extra electricity generated by the additional panels not be used if I don't have batteries ?

    I will speak to more installers but just interested in peoples thoughts and feedback on the above.



  • Registered Users Posts: 2,486 ✭✭✭ECO_Mental

    You will never hear people on here say they put up too many panels......

    Put up as much as you can fit on the roof, the panels themselves are relatively cheap its the getting up on the roof wiring etc costs most the money.

    You don't have an EV now but we are all going that way ao need to future proof yourself

    Also the more panels you have, on overcast days like today you base production will be higher. I have 6.1 kWp and its been cloudy all day but I have been outputting about 1kW all day and is covering all my consumption practically. Obviously less kWp installed will lower this line down.

    Go big or go home!

    6.1kWp south facing, South of Cork City

  • Registered Users Posts: 1,423 ✭✭✭DC999

    +1 to Eco+mental above.

    I’m the same as you with no battery. I’ve 16 panels and filled all the roof space. That’s only 4.9kWp (only 305w panels unfortunately). I’d get more I had space and money.

    You get ~20c FIT for each unit not used and sent back to the grid (only kicks in when you get a smart meter, not on a standard 24hr meter). So there is none lost. Having more panels is a good idea with no battery. Means when you are using power you’ve more panels to provide that.

    To give a rough sense of stats, I’ve generated 2300kWh in ~ 8 months since setup. 50% of that was used, and 50% went back to the grid at 20c FIT. I've an EV so that can soak up some but it's not in the driveway all the time when it's sunny (it's a 25kW battery as such)

    7-8 panels isn’t enough IMHO. Get as much as you can as that’s the least expensive time. Most of the solar setup cost is labour. 

  • Moderators, Sports Moderators Posts: 18,814 Mod ✭✭✭✭slave1

    GO as big as you can, the more the panels the more the inverter cost but the jump in price is very little, obviously there will be higher panel costs but with our dodgy weather you need all the help you can in over sizing.

    No-one has regretting going for too many panels and lots regrets going to small

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

    My Active Ads (

  • Registered Users Posts: 11,050 ✭✭✭✭the_amazing_raisin

    Cover the roof!!!! 😁

    There's a case for installing more panels than you need up to 6kWp of power

    If you're on a smart meter then you'll be paid for the amount of electricity you're feeding back to the grid.

    If you're on a day/night meter then you receive an estimated amount called deemed export. This changes the equation somewhat and actually makes batteries a lot more economical because you can charge your batteries at night when there isn't much sunlight

    But I digress...

    I think the simplest answer is to install as many as suits your budget. The more you install the more you'll generate and people tend to find uses for electricity

    I haven't had batteries for the past two months and I'd be watching the solar output on the app and when I see I'm sending a lot of electricity to the grid I'll put the washing or dishes on

    Battery just got installed today and it's a bit weird just being able to turn stuff on when I want and not wait for sunshine 😁

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

  • Registered Users Posts: 555 ✭✭✭idc

    Why stop at 6kWp? Surely better to install max allowed by your inverter. Depending on orientation of panels and in summer you may be clipped to the max of the inverter but the extra over the 6kWp will be of benefit the rest of the year ?

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  • Registered Users Posts: 11,050 ✭✭✭✭the_amazing_raisin

    If you go above 6kWp then you're off the NC6 and you'll need to pay NC7, which is probably overkill for the OP

    I know there's ways around it like export limiting, but I'm just trying to keep it simple

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

  • Moderators, Home & Garden Moderators Posts: 5,911 Mod ✭✭✭✭graememk

    It's more of along the lines of oversizing the array, eg 8kw of panels on a 6kw inverter

  • Registered Users Posts: 11,050 ✭✭✭✭the_amazing_raisin

    Well if there's no batteries like the OP was suggesting then there's not much point is there?

    Now I do think a small battery is always a good idea but the OP seems unconvinced about them

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

  • Registered Users Posts: 127 ✭✭connected1

    I agree with the comments here. Go for as many panels as you can fit (as long as they're not north-facing.

    The extra cost for the panels won't be a huge percentage of the overall price. On long sunny days, you'll get the benefit of the feed-in-tariff from the extra you generate. On short cloudy days you'll get more electricity for yourself.

  • Registered Users Posts: 29 iane87

    As a general rule of thumb you’ll generate 1000kWh per kWp of solar panels per year. Some of this usage will be at night and dull days so you can’t cover that usage, but you can offset the cost by exporting excess to the grid. Kind in mind you will only get roughly half price for export compared to import costs.

    depending on your budget you should install the most amount of panels you can afford. It is a 4-5 year payback on Solar PV at the moment. 10 panels is approx 4kWp, and also €2400 grant available. shop around, huge price differences out there.

    DHW diverter will be a game changer for you.

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