Solar Battery Storage in Northern Ireland (2026): Is It Worth It on NI Tariffs?

I have read all 394 quote requests that came through this site between 12 March and 22 September 2026, and 346 of them ticked battery storage. That is 88%. Almost everyone in Northern Ireland asking about solar wants a battery with it, so it deserves a straight answer on whether one pays here.

I run the /solar-today/ tracker, which models daily solar output for seven NI towns from measured sunlight, so I can work the battery maths from real 2026 NI weather rather than a GB average. The short version: on a normal NI tariff a battery earns its money from using your own solar in the evening, not from buying cheap power and selling it dear, and that makes it a good fit for some homes and a poor one for others.

The short answer

• A battery suits you if the house is empty most of the day, your electricity use peaks in the evening, you drive an electric car, you are on (or willing to move to) Economy 7, or you have 5kW or more of panels.
• A battery is harder to justify if someone is home through the day using power as it is made, your bill is under about £100 a month, or you already send your surplus into the hot water tank with a solar diverter.
• For most homes, 5kWh is the right size. Bigger only helps with an EV, a heat pump or night-rate charging.
• Get the battery priced as its own line on every quote. On my numbers below, a 5kWh battery used only for solar needs to cost about £1,870 or less to pay for itself inside a 10-year warranty.

Why NI batteries earn from self-use, not arbitrage

In Great Britain many battery owners charge from the grid on cheap overnight smart tariffs, priced half-hour by half-hour, and run the house on that power at peak times. That option does not exist here yet.

Northern Ireland has no smart meter rollout. The Department for the Economy published its smart meter policy decision on 29 April 2026, with NIE Networks to install them and the Minister asking for first installs in 2028 and completion by 2030 (DfE). Until then, the only cheap-rate options are Economy 7 and Power NI’s EV Nightshift, both of which need a day/night meter.

So for a typical NI home on a single-rate tariff, a battery does one job: it stores the solar you would otherwise export at 11.88p per kWh (Power NI’s rate from 1 October 2026 to 30 September 2027) and lets you use it later instead of buying electricity at 32.10p to 34.15p (Power NI’s domestic unit rates including VAT from 1 July 2026). Every unit shifted saves the gap between the two, about 21p.

The winter gap, from the tracker

This is the table that decides it. The tracker figures are the average daily output of a 4kW and a 6kW south-facing system across seven NI towns in 2026. The last column assumes a household uses 3 kWh of its solar as it is made during the day and puts the rest into a 5kWh battery, which then empties in the evening.

Month (2026)	4kW, kWh per day	6kW, kWh per day	5kWh battery filled from a 4kW array, kWh per day
February	3.06	4.59	0.1
March	6.49	9.75	3.5
April	11.01	16.52	5 (full)
May	13.03	19.55	5 (full)
June	11.89	17.84	5 (full)
July	14.74	22.10	5 (full)
August	9.14	13.71	5 (full)
September (1 to 22)	6.57	9.85	3.6

Tracker data checked on 23 September 2026. The generation figures are modelled from measured radiation, not metered from real panels; the method is on the 2026 generation page. Averages flatter the battery a little, because a dull day in June does not fill it.

Two things jump out. From April to August a 5kWh battery fills from solar on an average day. In February it gets almost nothing, because the house uses nearly every unit the panels make. The months from October to January are not in this year’s record yet, but February shows what they look like. A bigger battery changes nothing in winter, and in summer it only helps if you have the evening demand to empty it.

A worked example on a standard tariff

Add up the last column across February to September and a 5kWh battery on a 4kW array shifts about 980 kWh. Take off 10% for charging and discharging losses and you use about 880 kWh of it. At 33.1p, the midpoint of Power NI’s unit rates and the figure our solar calculator uses, less the 11.88p you would be paid to export it, that is worth about £187 a year. If the house uses 4 kWh as it is made instead of 3, it drops to about £177. October to January would add a little, not much.

On the same assumptions a 6kW array with a 5kWh battery comes out at about £206, because the battery fills in March and September too. A 10kWh battery on a 6kW array reaches about £373, but only if the house can use 10 kWh of stored power every evening, which most cannot without an EV or a heat pump.

Put that against price. Most battery warranties run 10 years. At £187 a year, a 5kWh battery pays back inside its warranty only if it costs about £1,870 installed, roughly £374 per kWh. Any battery quoted well above that is buying you convenience and resilience more than savings, and that is fine as long as you know it. Seeing the battery priced separately on two or three quotes is the only way to test it against that number, and you can request quotes here.

The Economy 7 exception

Economy 7 changes the maths because the battery can work in winter too, charging at night and running the house through the day.

Rates from the Consumer Council’s Economy 7 comparison table dated 28 August 2026, including 5% VAT (Consumer Council):

Supplier and tariff	Day rate	Night rate
Share Energy Eco 7	32.040p	15.560p
SSE Airtricity 1 Year Home, direct debit	36.180p	18.470p
Power NI Monthly Direct Debit e-bill	37.270p	17.820p
Power NI Standard (no contract)	39.650p	18.950p
Click Energy	39.771p	17.291p
Budget Energy Bill Pay	42.912p	18.138p

Night hours are 1am to 8am in winter and 2am to 9am in summer (Power NI). Power NI’s EV Nightshift tariff runs the same hours at 17.79p night and 37.20p day, but you must own or lease an electric car (Power NI).

Worked on Power NI’s direct debit rates: a unit bought at night costs 17.82p, or about 19.8p after battery losses, and replaces a day unit at 37.27p. That is roughly 17.5p saved per kWh. A 5kWh battery cycling that way on the roughly 180 days from October to March, when solar alone will not fill it, adds something like £140 a year on top of the solar savings.

The catch: Economy 7 day rates are several pence higher than a standard single rate. You only come out ahead if enough of your use moves to the night hours. With an EV charging overnight and a battery covering the day, most homes do. Without either, compare your last year’s usage on both tariffs before switching.

Which homes it suits

Reading the quote requests, 262 of the 394 came from homes spending £100 to £250 a month on electricity, and 249 were detached houses. That is the profile where a battery most often makes sense: enough use to empty it every evening and enough roof to fill it. The 66 homes on bills under £100 a month are the ones I would push hardest to get the battery priced separately and check it against the £1,900 figure.

Homes with an electric car are the clearest case, especially on EV Nightshift or Economy 7. Homes on oil heating (61% of NI homes, per NISRA 2024/25) with an immersion tank should compare a battery against a diverter first: a diverter costs far less and puts summer surplus into hot water instead.

Sizing: one installer’s rule of thumb

One of the installers that currently receive quote requests from this site (see how this site works) has published a view on this, so take it as one installer’s view. Its article on oversizing batteries argues that a battery only earns on what it discharges each day, that doubling the capacity roughly doubles the cost without doubling the saving, and that on short, dull NI days a large battery may hardly charge at all. Its rule is 5kWh for homes using under 4,500 kWh a year and 10kWh above that. The tracker table above agrees: the extra capacity mostly sits empty from October to March unless you charge it at night. It fits EcoFlow batteries and published package prices of £6,000 to £7,000 for 5kW of solar with a 5kWh battery when I checked on 23 September 2026.

Batteries NI installers name

I checked the websites of the installers in this site’s directory on 23 September 2026. Most show brands as logos, which tells you who they promote rather than what they fit as standard.

Battery	Named by	Manufacturer’s warranty (checked 23 Sep 2026)
EcoFlow PowerOcean	Clover Energy Systems, DSA Solar, one of this site’s quote partners	15 years down to 70% capacity, 6,000 cycles; 5kWh modules (EcoFlow)
BYD Battery-Box	Solarfix NI, Encom Energy, EECO, bee SOLAR	Check the UK warranty with the installer
Duracell Energy	Solarfix NI (Platinum Partner), EECO (Approved Installer)	Check the UK warranty with the installer
Tesla Powerwall 3	Clover Energy Systems, Solarfix NI, EECO	10 years, 80% capacity for UK and Ireland (Tesla)
SigenStor	Clover Energy Systems	10 years to 70% usable energy; 5kWh and 8kWh modules (Sigenergy)
PylonTech, Rosen	Encom Energy	Check with the installer
Dyness, PureDrive	HS Renewables	Check with the installer

One warning. GivEnergy Ltd went into administration on 9 April 2026 (Companies House, ESS News). The administrator said no further hardware warranties would be honoured by GivEnergy Ltd. The app is run by a separate company, GivEnergy Software Ltd, which is not in administration. Earlier versions of this page recommended GivEnergy, and at least one NI installer site still shows its logo. I would not buy a new GivEnergy battery until someone takes on the warranties. If you already own one, go to your installer first, and if you paid by credit card, ask your card provider about Section 75.

Tesla Powerwall in Northern Ireland

The Powerwall is the battery most people ask for by name, and until this summer it was hard to get here. On 4 August 2026 Segen, Tesla’s UK distributor, announced that certified installers in Northern Ireland can now supply and fit it (Segen). Clover Energy Systems shows a “T3 Powerwall Certified Installer” badge and EECO a Tesla certified logo; I have not confirmed either on Tesla’s own site.

The Powerwall 3 stores 13.5kWh. Tesla’s European warranty covers it for 10 years and promises 80% of that capacity at year 10 for UK and Ireland homes, with unlimited cycles for solar self-use and backup. It is a good product, but look at the tracker table: an average July day on a 4kW array left about 11.7 kWh after 3 kWh of daytime use, so a 4kW system never fills it on an average day. It makes sense with 6kW or more of panels, an EV, overnight charging, or if whole-house backup in a power cut is the priority. I could not get a verified NI price from Tesla, so ask for it itemised.

Backup in a power cut

Most batteries do not keep the lights on in a power cut by default. You need a hybrid inverter or battery that supports backup, and usually a changeover switch or a backup circuit wired in. If you are rural and lose power in winter storms, ask for this on the quote and ask which circuits it covers. There is more in the solar and power cuts guide.

What to ask for on a battery quote

• The battery priced as its own line, so you can check it against the £374 per kWh break-even
• Usable capacity, not just total capacity
• The UK warranty: years, capacity retained at the end, and any throughput cap
• Who you call if it fails, and whether the manufacturer is still trading
• Whether it can charge from the grid on Economy 7 or EV Nightshift
• Backup capability and which circuits it covers
• Batteries carry 0% VAT until 31 March 2027, so check the quote does not add VAT