Living off-grid with generators, batteries and bottled gas

Terms used

• Certificado de Instalación Eléctrica — The Certificado de Instalación Eléctrica is the certificate an authorised installer issues to confirm your electrical installation meets the rules.
• Boletín — The boletín is the everyday name for the electrical installation certificate.
• Memoria técnica — The memoria técnica is a technical report describing a power installation, required above certain power levels.
• Declaración responsable — The declaración responsable is a sworn statement to the town hall that lets certain works start without waiting for a full licence.

Key rules

• Installer: An authorised low-voltage installer must fit your solar and battery system and issue the electrical certificate.
• Butane price: The 12.5 kg bottle has a government-set maximum price, revised every two months with changes capped at 5%.
• Bulk propane price: The price of bulk propane is not regulated, so compare supplier offers and contract terms.
• Local rules: Licences and power thresholds differ by region and town, so ask your town hall before you buy.

Prices, project thresholds and the latest butane bottle price change often, so confirm them with local installers, your town hall and the Ministry for the Ecological Transition.

The short version

Off-grid life works, but you trade convenience for effort. Most people combine three things: solar panels with a battery for electricity, a generator for bad weather or heavy loads, and gas for cooking and heat. Each has real limits on reliability and running cost.

Solar and battery: your main power

Solar with a battery is the usual backbone. The battery is normally the biggest cost in the system. What you pay depends mainly on three things: inverter power, panel capacity and battery size in kWh.

• A small cabin or weekend system costs far less than a full-time home system.
• A full-time home with a battery of around 10 kWh or more costs several times a basic weekend setup.
• Lithium batteries, the inverter-charger, mounting, wiring and labour are priced separately. Remote sites cost more.

Get several itemised quotes and compare line by line. Prices change, so ask local installers for current figures.

The limit is weather. After several cloudy days in winter, a battery sized for normal use will run flat. Size the system for your worst weeks, not your average ones, and keep a backup.

Generator: the backup, not the plan

A generator covers cloudy spells and heavy loads such as pumps or power tools.

• Petrol units are the cheapest and suit occasional backup.
• Diesel units cost more but suit long daily running.
• Inverter models are quieter but cost more than conventional ones at the same output.
• Large diesel sets with an automatic transfer switch are at the top of the price range.

Running costs are mostly fuel, and they add up quickly if the generator is your main source. Compare prices by output, fuel type and noise before you buy.

Gas: cooking and heat

You have two routes.

Bottled butane. The 12.5 kg bottle has a maximum retail price set by the government. It is revised every two months, on the third Tuesday of January, March, May, July, September and November, and each change is capped at 5%. Check the latest resolution before you budget.

Bulk propane tank. This suits a full-time home with heavy gas use.

• An authorised gas installer must build the installation, issue a certificate and register it with the regional industry department.
• It needs periodic inspections, and minimum safety distances to buildings, boundaries and openings apply.
• The tank is either rented or lent free by the gas company in return for a supply contract, or you buy it yourself.
• Contracts commonly run about 3 to 5 years, with penalties for leaving early.
• The price of bulk gas is not regulated. The supplier sets it, so compare offers.

Before signing, ask what happens if you want to remove the tank or switch supplier. Switching is harder when the tank belongs to the company.

Power cuts if you are on a weak grid

If your home has a grid connection but is in the countryside, expect more outages than in towns. Rural dispersed zones are allowed the highest outage limits and have the worst records. Official yearly figures by zone are published by the Ministry for the Ecological Transition. Look up your zone before you buy. A battery or generator can still be worth having on a grid-connected rural home.

Paperwork and permits

An isolated system needs no grid access permit, but it is not paperwork-free.

• An authorised low-voltage installer must fit it and issue the electrical installation certificate, the Certificado de Instalación Eléctrica, also called the boletín.
• Above certain power levels you also need a technical project or memoria técnica, registered with the regional industry department.
• Your town hall will normally want a licence or a declaración responsable for the works.
• On rural land that cannot be built on, planning rules and any environmental or heritage protections also apply.

Requirements differ by region and town. Ask your town hall which licence your works need, and confirm the power thresholds with the regional industry department. The documents, checklist and FAQ below cover the details.

Choosing

The decision below helps you compare the options. As a rule, plan on solar and battery for daily power, a generator as insurance, and gas matched to how much you cook and heat.

Choosing between options

Which fuel or power source should you rely on for daily power and heat?

• Solar and battery: Fits if you want to live full time off-grid. The battery is usually the biggest cost, and a home system with a battery of around 10 kWh or more costs several times a basic weekend system.

• Petrol generator: Fits as a cheap backup for occasional cuts or a weekend cabin, not for long daily running.

• Diesel generator: Fits if you need to run it for long hours every day. It costs more to buy than petrol, and larger sets with an automatic transfer switch cost the most.

• Bulk propane tank: Fits if you use a lot of gas and can accept a 3 to 5 year supply contract.

• Bottled butane: Fits if you use little gas and want a regulated price, with no installation or long contract.

Use solar and battery as the base for a full-time home, add a generator as backup, and choose bulk propane over bottles only when your gas use justifies a long contract.

Documents you need

• Certificado de Instalación Eléctrica (boletín): the electrical installation certificate issued by the authorised low-voltage installer (empresa instaladora) for your solar and battery system.

• Technical project or memoria técnica for the solar and battery system, needed above certain power thresholds and registered with the regional industry department.

• Town hall licence or declaración responsable (a sworn statement that lets works start) for the installation works.

• Installation certificate for a bulk propane tank, issued by the authorised gas installer and registered with the regional industry department.

• Gas supply contract for a bulk propane tank, which sets the tank rental or loan terms, the contract length and the early-termination penalty.

Checklist

• Look up the yearly outage figures for your zone on the Ministry for the Ecological Transition website if you plan to rely on the grid.

• Ask your town hall which licence or declaración responsable your solar and battery works need.

• Check the planning, environmental and heritage rules for your rural land with the town hall and the regional government.

• Get several itemised quotes covering the battery, inverter-charger, panels, mounting, wiring and labour.

• Compare generator prices by output, fuel type and quiet inverter models before you buy.

• Ask for the safety distances, inspection schedule, contract length and tank removal terms before signing a bulk propane contract.

Frequently asked questions

Is bulk propane priced the same way as bottled butane?

No, the price of bulk propane is not regulated, so the supplier sets the price per kg or litre. Compare offers from several suppliers. Check how long the contract runs, which is commonly 3 to 5 years, and what the penalty is for leaving early.

Can I switch gas supplier if the tank belongs to the company?

Possibly, but it depends on your contract, because tanks are often rented or on free loan tied to a supply contract. Before signing, check the early-termination penalty and who removes the tank if you switch.

Are power cuts worse in the countryside than in towns?

Yes, rural dispersed zones are allowed the highest number and length of interruptions and register the worst outages. If you rely on the grid there, a battery or generator as backup is worth pricing.