Off-grid power in Spain

Start here: off-grid power in Spain

Off-grid power is the system people worry about most and understand least. The panels are the easy part. What decides whether a system works is winter, the inverter and the batteries, and which jobs you ask electricity to do. This page is the order I’d think it through in.

1. Work out what you’ll use, honestly

A comfortable all-electric home uses 20–40 kWh a day. A careful one that heats with wood and cooks with gas can live on far less: ours does. The biggest decisions aren’t about panels; they’re about whether heating, hot water and cooking run on electricity. How many solar panels you need has a table of typical loads and a worked example.

2. Size for winter, not summer

A kilowatt of panels near Alicante gives about 7.5 kWh a day in summer but only 2.9 in winter. In Galicia the winter figure is under 2. Off-grid, there’s no grid to cover the gap, so you design for December and accept a surplus in July. The region guides give winter figures for each area:

• Andalucía, Murcia and the Valencian Community: about 2.8–3.3 kWh a day per kW
• Castilla-La Mancha and Catalonia: about 2.2–2.8
• Galicia: about 1.8–2.0

3. The inverter is the real limit

The inverter decides how much you can run at once and how many panels you can add later. Oversize its solar input from the start: it’s the cheapest insurance you can buy. Motors like borehole pumps pull a surge when they start, which is why I fitted a soft starter to ours.

4. Batteries for the night and the grey days

Lithium iron phosphate (LiFePO4) is now the standard. Storage should cover at least a full day of use, plus margin for cloud. My battery guide covers sizing, prices, where to put them and how to look after them in a Spanish summer.

5. Decide about a backup

We have no generator and live within what the sun gives us. Many households, especially further north, are glad of one. Do you need a generator? sets out the costs and the wiring, and the generator I swore I’d never buy is the story side of it. Wind rarely earns its place; here’s why.

What it costs

Equipment prices have fallen a long way. Off-grid kits with lithium batteries currently start at about €2,400–€2,700 for 5 kWh and €3,600–€3,700 for 9.6 kWh, and a premium Victron kit with 9 kWp of panels and 9.6 kWh of storage is about €9,900. Those are equipment prices only: mounting, cabling, installation and legalisation come on top. An off-grid installation still needs its electrical certificate, which you’ll want for any regularisation, grant or sale.

Living with it

The difference between a system that copes and one that doesn’t is often habits. Run the washing machine and the pump at midday, not at night. Learn what your background load is at 3am. Find uses for the summer surplus, as I did in the summer I stopped wasting solar power. And keep an eye on the cheap stuff that adds up, from extension leads to a home cinema.

The bigger loads each have their own guide: the off-grid kitchen, workshop tools, air-con and charging an electric car off-grid. We run a small EV ourselves, and it changed how we use the summer surplus.

Choosing an installer

A good installer is worth more than a good brand. Ask how they sized the system (if they don’t ask about your winter use, be wary), what the inverter’s maximum solar input is, whether the batteries are on the inverter maker’s compatibility list, and whether legalisation is in the price. Off-grid is a specialism, so ask to see one they’ve done. The directory lists solar installers and battery and generator suppliers by province.