In Mallorca a home battery is worth it for most houses that are lived in, and for residents the 45% FACTOR grant until 28 February 2027 tips it clearly. The reason is the gap between what you pay for electricity, about €0.22 per kWh, and what you're paid for surplus, €0.04 to €0.06. Every kWh you store at midday and use in the evening is worth four or five times more than exporting it. The exceptions are homes that are empty most of the year and systems so small they have no surplus.
The problem a battery solves
A solar system produces most between 10 am and 4 pm. A household uses most between 6 pm and 11 pm. Without storage, a typical Mallorca home uses only 35 to 40% of its own solar directly and exports the rest at a few cents. A battery lifts the share used at home to 70 to 85%.
On a 6 kWp system producing 9,500 kWh a year:
| No battery | With 10 kWh battery | |
|---|---|---|
| Used at home | 3,600 kWh (38%) | 7,100 kWh (75%) |
| Value of self-use at €0.22 | €790 | €1,560 |
| Exported | 5,900 kWh | 2,400 kWh |
| Value of exports at €0.06 | €350 | €145 |
| Yearly saving | €1,140 | €1,705 |
The battery adds about €565 a year here. At €6,000 installed that's a 10 to 11-year payback on its own, within a 12 to 15-year life. With FACTOR returning 45% (about €2,700 on this battery), payback drops to about 6 years. Add the new 10% state deduction and it's better still.
Sizing
Roughly match the battery to your evening and night consumption:
- 5 kWh: a flat or a frugal couple.
- 10 kWh: a family home with evening cooking and some air-conditioning.
- 15 kWh or more: a villa running air-conditioning at night, or a home with an EV charged in the evening.
A battery much bigger than your evening use sits half-empty and earns nothing on the unused part. A rule of thumb is 1.5 to 2 kWh of battery per kWp of panels.
When a battery doesn't pay
- A house empty most of the year. The battery cycles only when someone's home. If the house is used three months a year, size it for those months or skip it.
- A system with no surplus. A 3 kWp system on a home that uses 20 kWh a day has little left over to store.
- Non-residents without the grant. Payback stretches to 10 years or more. Still viable over the battery's life, but many owners abroad start with panels and add storage later.
Backup power
Rural lines and storms make cuts a reality in parts of the island. A hybrid inverter with a backup function can keep an emergency circuit (fridge, lights, router, alarm, a pump) running through a cut, but only if it's specified: not every battery system does this by default. Ask for it explicitly, and ask which circuits it covers.
New system or retrofit
- With a new system, a hybrid inverter runs panels and battery together. It's the cleanest design and the cheapest.
- Adding to an existing system, you either add an AC-coupled battery with its own inverter alongside the existing one, or replace the existing inverter with a hybrid. Budget €800 to €1,500 extra. If your inverter is over eight years old, the swap is often the better path because it's due for replacement anyway.
Lithium, warranties and placement
All current home batteries are lithium, mostly LiFePO₄. Look for usable capacity in kWh (not just nominal), a warranty of 10 years or around 6,000 cycles, and a manufacturer with a Spanish service presence. FACTOR requires a 5-year manufacturer warranty and excludes lead-acid. Place the unit in a cool, ventilated spot: a garage, a utility room or a shaded store, not a west-facing shed.
The FACTOR grant in practice
Residents get 45% of the battery cost, measured against a reference of €910 per kWh for batteries up to 10 kWh (€650 per kWh from 10 to 100 kWh). The grant can't exceed what you actually paid. The window closes on 28 February 2027 or when the €4.1 million budget runs out, and it's first-come, so installers are applying as soon as systems are commissioned. Most installers in our network handle the application. See the subsidies page.
Prices
Installed lithium batteries run €480 to €700 per kWh: about €3,200 to €4,500 for 5 kWh, €5,000 to €7,000 for 10 kWh and €6,800 to €9,500 for 15 kWh. The solar calculator prices a battery with your system and shows the grant.
The decision
Lived-in home, resident, evening consumption: get the battery now, while FACTOR is open. Second home used in summer: size a small battery for the summer evenings, or start with panels. Finca on a weak rural line: battery with backup, regardless of the economics.
Common questions
How long do lithium batteries last?
Most are warranted for 10 years or 6,000 cycles; in home use that's 12 to 15 years. Degradation is gradual.
Does a battery work in a power cut?
Only if the inverter has a backup function and the installer wires an emergency circuit. Ask for it specifically.