Sizing for Mallorca
Off-grid design starts with the loads, not the roof. Fridges, pumps, water heating, air-conditioning and a pool pump are the big ones. A year-round finca for two to four people typically needs 5 to 8 kWp of panels and 20 to 30 kWh of lithium storage. Winter is the design case: December produces about a third of what June does, so the battery and a generator bridge the gap.
Three choices shape the price:
- Lithium vs lead-acid. Lithium costs more up front, lasts two to three times longer and can be run harder. Nearly all new systems use it.
- Water heating and cooking. Moving these to gas or a heat-pump water heater cuts the battery you need.
- Generator integration. An automatic-start generator that charges the battery when it runs low is the difference between a system you trust and one you babysit.
Upgrading an old system
Many fincas have 10 to 20-year-old systems with tired lead-acid banks and a petrol generator doing too much work. A new hybrid inverter and lithium bank, keeping good panels where possible, usually transforms them for €8,000 to €15,000.
Rules
Isolated systems are outside the self-consumption register, but they're still electrical installations: the installer issues the electrical certificate (CIE) and files a memoria técnica (up to 10 kW) or a project. If you plan to sell or get a tourist licence, this paperwork matters. On rustic land the panels themselves need a municipal licence; roof-mounted on an existing legal building is normally admitted, ground-mounted depends on the Consell de Mallorca's territorial plan. See the permits page.
Prices
Complete installed off-grid systems for a finca run from about €12,000 for a modest weekend house to €25,000 to €35,000 for a year-round home with air-conditioning. The battery is usually half of it.
Typical prices
| Job | Typical installed price | Notes |
|---|---|---|
| Home EV charger, 7.4 kW | €800 to €2,000 | FACTOR pays 70% to residents, max €2,500 |
| Off-grid finca system, 4 to 8 kWp with 15 to 30 kWh | €12,000 to €35,000 | Battery is about half; generator integration extra |
| Legalising an existing system | €300 to €1,000 | Up to €2,500 with works to meet code |
| Engineer's project (above 10 kW) | €600 to €1,500 | Plus works direction certificate |
| Energy certificates before and after | €250 to €500 | Needed for the 40% and Balearic deductions |
incl. 21% IVA. Budget ranges from quotes across the island; real prices depend on a site visit.
What a good installer includes
- A load list and a winter energy balance, not just a kWp number
- Lithium battery with usable kWh and cycle warranty stated
- Hybrid inverter with generator auto-start
- Remote monitoring you can read from abroad
- Electrical certificate and memoria or project filed
Watch out for
- A system sized on summer production
- No winter plan or generator
- Lead-acid with a short warranty
- Panels on the ground on rustic land without a licence
Common questions
Is off-grid cheaper than connecting to the grid?
Often, once the connection quote passes €15,000 to €20,000, which it does quickly beyond a few hundred metres of line. An off-grid system also has no standing charges.
Do I still need a generator?
For a year-round home, usually yes, as backup for the odd long run of cloudy winter days. It should run a few dozen hours a year, not every evening.
Does an off-grid system need paperwork?
Yes. It's an electrical installation: the installer issues the certificate and files a memoria or project. It doesn't join the self-consumption register.