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Home Battery Sizer (Ireland)
“Is a solar battery worth it?” is a live question for Ireland’s 100,000-plus solar homes, and the Clean Export Guarantee genuinely changed the answer. Storing your own solar now saves only the gap between the import and export rate. This tool models both honest value paths — storing solar, and night-rate arbitrage — sizes a battery to your actual usage, and returns a straight verdict, including “won’t pay back on savings, buy it for backup”.
Reviewed 23 lug 2026
The tool
Open the tool full-screen ↗Use it right here — nothing is saved, and there’s no sign-up.
This tool may link to relevant products and services to keep it free. Affiliate links are marked and are placeholders during this early phase — see our affiliate disclosure
What to know
There are two ways a battery earns its keep. The first is storing surplus solar to use in the evening instead of buying it back — worth the difference between the import and export rate, which is smaller than it used to be. The second is night-rate arbitrage: charging the battery on a cheap night tariff and discharging it at peak, which works even without solar if the day–night price gap is wide enough.
Size matters as much as payback. A battery bigger than your shiftable evening load just sits half-empty; too small and you still buy peak power. The tool sizes to the load you can actually shift and is honest when the maths says a battery won’t pay back on savings alone — at which point the real reason to buy one is resilience during power cuts, not the bill.
How this tool works
No sign-up, nothing saved — here is what it does with your answers.
- Enter your usage, whether you have solar, and your import, export and night-rate prices.
- The tool models storing solar versus night-rate arbitrage and sizes to your shiftable load.
- You get a recommended size and one of three honest verdicts, including “buy it for backup, not savings”.
Frequently asked questions
Does a solar battery pay for itself in Ireland?
For most homes, not on solar savings alone since the Clean Export Guarantee. Night-rate arbitrage can help, and some buy a battery mainly for power-cut resilience. The tool tells you which case is yours.
What size battery do I need?
Enough to cover the evening load you can actually shift — no more. A battery larger than your usable load wastes capacity. The sizer calculates this from your numbers.
Can a battery power my house in an outage?
Only if it’s specified with backup capability — not all installations include it. If resilience is your goal, see the backup power calculator too.
Related tools
Working through a project? These pair up.
Solar Diverter Payback Calculator
Since the export guarantee, is an Eddi still worth it? The honest sum.
Power Cut Backup Calculator
What size power station keeps your essentials running in an outage?
These tools give honest indications using current published rates and guidance, not professional advice. Rules, prices and provider terms change — always confirm the current figures with the relevant official body, provider or qualified professional before you commit.