In the weeks after the lights went out across Spain and Portugal, backup-power installers across Europe fielded a wave of calls from households who had never priced battery storage before. Most of them did the sensible first thing and requested three quotes. Then a lot of them went quiet for a month — because the honest answer to “what do I actually buy” turns out to require comparing at least three different inverter architectures, six brand ecosystems, and a national incentive scheme that reads differently in Berlin than it does in Bilbao, and nobody hands you that comparison before the first phone call rings off. This is that comparison, built once so you don’t have to rebuild it per country.
If you want the full story of what actually caused the blackout — the grid physics, the ENTSO-E investigation, why it wasn’t really about “too much solar” — that’s covered in full here. This report starts from the other end: you’ve already decided backup power is worth having, and you need to know exactly what to buy, in your country, this year.
In this report
The decision before the brand decision
Ask six installers whether you should buy sonnen or BYD or Huawei and you’ll get six confident, contradictory answers, because that’s the wrong question to ask first. The question that actually decides which brands you’re even shopping is architecture — how the battery physically connects to your solar and your house — and it usually gets settled the day you buy solar, months or years before backup power ever crosses your mind.
| Architecture | What it means | Best if | Example brands |
|---|---|---|---|
| AC-coupled retrofit | A separate battery with its own inverter/charger sits on your existing house wiring, alongside whatever solar inverter you already have | You already have solar and don’t want to touch the existing inverter | Victron MultiPlus/Quattro, most standalone retrofits |
| DC-coupled hybrid | One hybrid inverter runs the solar array and the battery together on the DC side, planned in from the start | You’re installing solar and storage at the same time, or replacing a failed inverter anyway | Huawei SUN2000 + LUNA2000, sonnen, most BYD Battery-Box installs |
| All-in-one (AIO) | Battery and hybrid inverter ship as a single sealed box | You want the simplest possible install and don’t mind a closed ecosystem | Tesla Powerwall 3, GivEnergy’s AIO range |
The lock-in is the part nobody mentions at the quote stage. A DC-coupled hybrid inverter is generally married to its own maker’s battery family — a Huawei SUN2000 inverter takes Huawei LUNA2000 batteries, not BYD’s. Buy the wrong architecture for what you actually want, and the fix isn’t a new battery. It’s a new inverter.
Key number
Retrofitting a battery-ready hybrid inverter after the fact typically adds €1,500–3,000 in extra hardware and labour beyond what the same inverter would have cost specified at the time of the original solar install — a bill almost nobody sees itemised until the architecture decision has already been made for them.
Battery-first vs. inverter generator, by the numbers
Cross the Atlantic and the reflex answer to backup power is a diesel or propane standby generator; on this side of it, the reflex is increasingly a battery, and the general case for why comes down to load shape and siting as much as sentiment. The number that actually settles it, though, is a grid-reliability number almost nobody looks up before buying either one.
Most Northern and Western European grids are extremely reliable — the average household loses well under an hour a year to outages in a typical year, headline blackouts aside. A generator only earns its keep on the days the grid actually fails. A battery earns its keep every single evening, shifting solar you already generated into the hours you actually use it, whether the grid behaves itself or not.
Here’s that arithmetic against a household the blackout piece didn’t size — a home heated by an air-source heat pump rather than gas, where the compressor itself, not just its electronics, sits on the critical-circuit list.
| Circuit | Running watts | Hours/day | kWh/day |
|---|---|---|---|
| Fridge/freezer | 120W (cycles ≈1/3 of the time) | 8 | 0.9 |
| Router, modem, wifi | 25W | 24 | 0.6 |
| LED lighting, several rooms | 100W | 6 | 0.6 |
| Phones, laptops | 80W | 10 | 0.8 |
| Air-source heat pump, reduced/emergency duty | ≈800W average | 6 | 4.8 |
| Total critical load | ≈7.7 kWh/day |
A 5kWh unit covers barely sixteen hours of that and needs the sun back the next morning to recover. A 10kWh unit — the size most sonnen, BYD and Huawei installers quote as a common starting point — covers a full day with headroom. A 15kWh unit, where sonnen’s mid-tier and BYD’s larger Battery-Box stacks both sit, covers very nearly two days on stored charge alone: more than enough for all but the most extreme repeat of last April.
Put a price on that runway and the generator-versus-battery question mostly answers itself. A 10kWh mainstream battery at roughly €600–800 per kWh installed lands near €6,000–8,000 — expensive on the invoice, but working every day, whether or not the grid ever blinks. A petrol or LPG inverter generator capable of the same heat-pump surge costs a fraction of that up front, commonly €700–1,200 — but it only turns a profit on the days the grid actually fails, which on most Western European grids is well under an hour a year. Divide either cost by the days it’s actually useful, and the battery is the cheap option. It’s just billed monthly, in self-consumption savings, instead of once, in relief.
The European brand landscape
Once you know which architecture you’re buying, the brand list shortens fast. Here’s where the six names you’ll hear most in a European or UK quote actually sit.
| Brand (origin) | Architecture | Positioning | Typical installed range |
|---|---|---|---|
| sonnen (Germany) | DC-coupled hybrid | Premium build, long warranties (10-year/10,000-cycle class), own VPP trading scheme (sonnenCommunity) | €6,000–12,000 (5–20kWh) |
| BYD Battery-Box (China) | DC-coupled, pairs with most third-party hybrid inverters | Best €/kWh of the mainstream brands; the most installer-agnostic modular choice | €4,000–8,000 (5–20kWh) |
| Huawei LUNA2000 (China) | DC-coupled, paired to Huawei’s own SUN2000 inverter | The mainstream default for most European/UK installers; strong monitoring app | €6,000–12,000 (10–15kWh) |
| Victron Energy (Netherlands) | AC-coupled, modular | The off-grid specialist’s choice — most flexible for complex loads, cabins and boats with no simple grid tie; steeper install | Varies widely by configuration |
| GivEnergy (UK) | All-in-one hybrid | UK-focused value AIO, built around the standalone 0% VAT retrofit market | £4,500–7,000 (typical 10kWh) |
| Tesla Powerwall 3 | All-in-one hybrid | Simplest single-box install; premium price; closed Tesla-app ecosystem | £8,000–12,000 / €900–1,100 per kWh |
None of those ranges include your country’s incentive — see the next section for that — and installer labour, scaffolding and DSO approval can move the final number by a few hundred to a couple of thousand euros either way. See current packages sized against a household like yours, with 2026 European and UK installed pricing:
2026 incentives, country by country
Incentive schemes are the part of this decision that moves fastest, and the part most buying guides go stale on within a year. Here’s what was live heading into the second half of 2026.
| Country | 2026 headline incentive |
|---|---|
| United Kingdom | 0% VAT on battery storage, including standalone retrofits, via an MCS-certified installer — confirmed through March 2027 |
| Germany | 0% VAT on qualifying PV-plus-storage systems, plus KfW low-interest loans and regional top-up grants worth up to roughly €3,200 in qualifying cases |
| Italy | Bonus ristrutturazioni (bonus casa): a 50% personal income-tax credit spread over 10 years for your primary residence (prima casa) — 36% for second homes — plus 10% VAT instead of the standard 22% |
| Spain & Portugal | No single national figure — autonomous-community and regional grants funded via European recovery money, several topped up since April 2025; allocations run out and reopen on a cycle, so timing matters |
Treat every figure above as a starting point, not a budget line — regional top-ups, allocation caps and installer certification requirements change what you actually qualify for, and the only number that matters in the end is the one on your own quote.
- Ask whether your installer is certified for the scheme you’re counting on — UK 0% VAT and most European grants both require it.
- Confirm your region’s current allocation before you budget; some Spanish and Portuguese schemes close and reopen mid-year.
- Size against your real critical-load kWh/day from the table above, not the battery’s marketing headline capacity.
- Get the architecture decision right first — it decides which of the six brands above you’re actually allowed to buy.
Members only · free account
The full country cost tables
What each incentive above is actually worth in euros on a real 10kWh system — country by country, including the Netherlands, France, Poland and Ireland, updated quarterly — plus a line-item installed-cost table by brand. Free with a Grid CEO account.
Common questions
Do I need solar to add a home battery in Europe?
No. You can retrofit a battery standalone in most European and UK markets, charging it from cheap overnight grid rates instead of solar. It’s usually still better economics to add it alongside new solar, since the inverter and installer labour are shared across both, but a standalone retrofit is a normal, incentive-eligible purchase on its own.
Can I mix brands — keep my existing solar inverter and add a different battery?
It depends entirely on the architecture from the table above. AC-coupled add-ons (the Victron-style approach) are the most brand-agnostic, since the battery brings its own inverter and simply sits alongside whatever you already have. DC-coupled hybrid systems mostly lock you into that inverter maker’s own battery family — a Huawei inverter only takes Huawei batteries. All-in-one units like Powerwall or GivEnergy’s AIO range are single-brand by definition.
Is a battery actually cheaper than a generator over time?
Usually, yes, once you price both against how often you’ll actually use them. A battery earns its cost back daily through solar self-consumption, whether or not the grid ever fails. A generator only earns anything on the days the grid actually goes down — well under an hour a year on most Western European grids — so its effective cost per day of real use is far higher, even though its purchase price is lower.
What size battery would actually get me through a repeat of the Iberian blackout?
For a modest gas-heated home, 5–10kWh comfortably covers the critical-load list (see the full household breakdown here). For a heat-pump home, where the compressor itself needs power, size closer to 10–15kWh — enough for roughly two days on stored charge alone, which would have covered the entire April 2025 outage without the panels recharging it once.