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Battery or sell back to grid

  • 05-05-2023 11:03am
    Registered Users Posts: 124 ✭✭

    We had a consultation with a solar panel installer this week.

    They advised us against getting the battery, saying that selling back to the grid makes more sense. I was pretty swayed during the meeting, but my husband wasn't and on further reading (we're very new to all this!), it seems like a battery could still be a good choice. But it's very expensive (and the system we're looking at is already expensive enough).

    With the investment we're making I just want to make sure we're making the right choice! Is it an either or situation? If we get the battery, can we no longer sell back to the grid?

    What have people found works in their experiences? Is it better to pay less, get no battery and sell on excess, or have the battery and save on getting electricity from the grid?


  • Registered Users Posts: 823 ✭✭✭Boardnashea

    Use as much of your production yourself - that means get a battery.

    Your battery won't be big enough to take all your summer production, you will still be exporting.

    Get a day/night meter sorted if your don't already have on. Do not go for a smart meter yet. Put night rate power into your battery in the winter and use it during the day rate hours. The export payment will be based on the size of your equipment until you have to move to a smart meter. So you might not export anything and still get paid for export.

  • Registered Users Posts: 10,816 ✭✭✭✭the_amazing_raisin

    I'd recommend reading this thread which asked a similar question

    Personally for us the battery has so far been of great benefit, we've managed to vastly reduce our consumption versus having solar with no battery

    It's early days yet but to give you some idea I've roughly calculated the electricity bill for this month will be under €50 down from something like €165 for the same time last year (before some of the big price increases, would probably be over €200 for the equivalent usage this year)

    Our solar use was around 50-60% before the battery and we'd be watching the sun trying to gauge when to start appliances

    Now we just start stuff around midday and between the battery and solar we've enough power to run them. Our solar use rate is now typically over 95%

    Regarding getting paid for selling electricity to the grid, there's a lot of misinformation out there so be very careful

    If you're on a smart meter, it'll measure the number of kilowatt hours (kWh, aka units on your bill) that you sell to the grid and your electricity supplier will credit your account for this

    If you're on a day/night meter, or an old 24 hours meter then you'll receive an estimated amount called deemed export.

    In both cases it's almost always better to use the electricity generated from PV instead of selling to the grid. For example if you are a Flogas customer you'll be selling electricity to them at 22c/kWh. But you're buying it from them at 38c/kWh, so that represents a 16c loss on every kWh you could have used yourself

    Another trick with a battery is that you can charge them form the grid at night on a cheaper tariff. This is particularly useful during winter when there isn't much sunlight

    As some general advice, be very careful with the sales pitch from many solar companies, there's a few shady ones that have made fairly outlandish claims to get business or appear cheaper. There's also companies that offer "premium" equipment which in reality isn't any better than the others

    Get at least 3 to 4 quotes for the same system and see what they come back with

    Your starting point should always be your electricity consumption, and how many panels you can fit on your roof. This determines the maximum amount of energy you can get

    You can then look at how much of this you'll use versus selling to the grid. As I said, without a battery you might be around 60% and with one you'll be closer to 90%. This then allows you to figure out the savings and payback period, do it for but with and without batteries and see what it turns out

    Another thing to consider is going without the battery at first and then adding one later, this is what I did. You need to be clear with the installer as they'll need to install a different type of inverter called a hybrid inverter to accommodate a battery

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

  • Registered Users Posts: 1,405 ✭✭✭DC999

    Plus 1 for 'going without the battery at first and then adding one later' - I don't have one after nearly 1 year.

    I'd like one but money tree wouldn't stretch and payback is much longer now with ~20c FIT. So units I don't use aren't lost, I get ~1/2 a credit for that (20c FIT v 40c when I buy them back). Need a smart meter for FIT. Or a Day/Night meter.

    If you've an EV in the driveway during the sunny hours, that's a much larger battery to soak up the excess. Need a smart charger like the Zappi. ~1.5k supply and fit and get €600 grant (if it's your 1st charger).

    Btw, if that installer required you and your partner to both attend that consultation, and gives you a rebate if you get X number of referrals for them, and are part owned by a major energy company, they are the more expensive ones in the market. We don't name names here. You'll get less expensive quotes with no reduction in quality or service.

  • Registered Users Posts: 5,763 ✭✭✭con747

    Don't expect anything from life, just be grateful to be alive.