Smart and night-rate tariffs promise cheaper electricity — but only if you can use power at the right times. Here’s how they work in Ireland and how to tell if one will actually save you money.
How they work
- Night-rate (day/night): two prices — a cheaper rate at night, a higher one during the day. A classic fit for storage heating, immersion heaters and overnight EV charging.
- Smart tariff: uses your smart meter to charge different rates by time of day, often with a cheap off-peak window and a pricier peak window (typically early evening). Some also offer free or cheap weekend hours.
The catch is the same for both: the off-peak saving only helps if you use enough electricity off-peak to outweigh the higher peak prices.
Who saves money
You’re a good candidate if you can shift significant usage to off-peak:
- EV owners charging overnight — often the single biggest win.
- Heat pump users who can heat water or the home in cheaper windows.
- Households happy to run the dishwasher, washing machine, dryer and immersion off-peak (timers help).
- Battery owners who charge cheaply off-peak and use it at peak — see is a solar battery worth it?
Who’s better on a flat rate
If your home is busy in the early evening (cooking, heating, TV, kids) and you can’t move that usage, the higher peak prices of a smart tariff can wipe out the off-peak savings. A simple flat rate may cost you less — and it’s easier to compare.
How to decide
- Check your smart meter data (via your supplier’s app) to see when you actually use electricity.
- Estimate how much you could realistically shift to off-peak.
- Compare a smart tariff’s estimated annual bill against a good flat rate — on a CRU-accredited comparison site.
It all sits alongside the biggest win of all: switching supplier and the other tips in how to reduce your electricity bill.
Worked example: cheap night units, a more expensive year
These rates are hypothetical, not a current supplier offer. A home uses 4,200 kWh a year. A flat plan charges 30c/kWh and €300 a year in standing charges: €1,260 + €300 = €1,560.
A day/night plan charges 35c during the day, 18c at night and €350 standing charge. If 35% of use falls at night, daytime consumption is 2,730 kWh and night consumption 1,470 kWh. The total is €955.50 + €264.60 + €350 = €1,570.10. The tempting night price still leaves this household €10.10 worse off.
The break-even night share is about 36.4% with those inputs. At 50% night use, the day/night annual cost becomes €1,463, saving €97. The useful question is whether your actual usage can reach that share inside the offered hours, without increasing total consumption. Try the tariff calculator with your own figures.
Match the meter data to the tariff window
Use a full year where possible so winter heating and summer patterns are both represented. Add consumption falling inside the proposed cheap window and divide by total consumption. Do not assume a midnight-to-8am usage total also represents a shorter EV tariff window.
A three-rate smart tariff needs a separate peak bucket. A dynamic tariff needs interval prices and interval consumption; neither can be reliably evaluated by treating everything outside the night window as a single day rate.
Check recurring levies, discounts, contract duration and exit fees separately. Our tool accepts other annual charges, but not complex bundles or conditional cashback. Use the CRU’s accredited comparison services for live offers. For solar export eligibility, consult ESB Networks’ deemed export guidance.
