An **off-grid solar installation** — also called an off-grid solar kit or standalone system — powers a home with no grid connection at all. To run for years without surprises it needs three things done properly: **legalisation under RD 244/2019**, **power continuity (ATS and EPS)** and a **properly sized battery bank**. This is exactly what we apply in every project, like the one in Loja: 28 Aiko 610 W panels, a 15 kW Deye hybrid inverter and 32 kWh of MTS batteries.
## Legalising an off-grid system: RD 244/2019
**Royal Decree 244/2019** regulates self-consumption in Spain, including systems with no grid connection. In practice, legalising an off-grid installation in Andalusia means:
- **Electrical certificate (CIE)** issued by an authorised installer, under the REBT low-voltage regulation.
- **Technical project** where the power rating requires it, endorsed by the official engineering college.
- **Registration in the Andalusian self-consumption register**, in the category without grid connection.
- Documentation of the equipment: inverter, batteries and protections.
Without legalisation there are no warranties, no insurer will cover a claim and the system cannot be registered as part of the property. We hand over every installation with all paperwork completed.
## ATS vs. EPS: they are not the same
They are often confused, but they do different jobs — and a serious off-grid system has both.
**ATS (automatic transfer switch)** — switches the home between energy sources: solar inverter, generator or grid. It does so automatically, with no noticeable interruption. If the batteries drop below a set level, the ATS starts the generator; once they recover, it switches back to solar.
**EPS (Emergency Power Supply)** — an output on the hybrid inverter itself that keeps feeding critical circuits even if everything else fails, directly from the panels and batteries. We wire the fridge, lighting, water pump, internet and main sockets to the EPS.
In short: the **ATS decides where the power comes from**; the **EPS makes sure the essentials never go off**.
## Batteries: how many kWh do you need?
The battery bank rules an off-grid system. Realistic sizing by use:
| Use | Battery | Turnkey price |
|---|---|---|
| Weekend cottage | 10–15 kWh LFP | from €8,500 |
| Daily-use home with air conditioning | 15–25 kWh LFP | €16,000 – €26,000 |
| Self-sufficient finca (pool, irrigation) | 30–40 kWh LFP + ATS + EPS | €28,000 – €45,000 |
We install modular, expandable LFP batteries: start with what you need today and extend later without changing the inverter.
## A real example: finca in Loja (Granada)
In Loja we installed 28 Aiko 610 W panels (17.1 kWp), a 15 kW Deye hybrid inverter and 32 kWh of MTS storage, with ATS and an EPS output. The house runs without the grid: by day it lives off the sun, by night off the batteries, and the ATS only starts the generator if ever needed. The price of a system like this: between €27,500 and €32,500, legalisation included.
## Frequently asked questions
How much does it cost to legalise an off-grid solar installation?
Legalisation under RD 244/2019 (certificate, technical project where required and Andalusian register entry) is included in our turnkey quotes. As a standalone item it usually runs between €600 and €1,500 depending on the power rating.
Do I need a generator as well as batteries?
Recommended for full-time homes. The ATS connects it automatically only when the batteries drop below the set level; the rest of the year it stays off. Weekend cottages with 10–15 kWh usually manage without one.
What is the difference between an off-grid solar kit and a custom installation?
An off-grid solar kit is a standard package you install yourself or through a third party, with no ATS, no configured EPS and no legalisation. A custom installation includes consumption calculations, battery sizing, ATS, EPS and full RD 244/2019 legalisation.
Can I extend the batteries later?
Yes. The modular LFP batteries we install accept parallel expansion. In the Loja project, for example, the 32 kWh of MTS storage can grow to 40 kWh without replacing the 15 kW Deye inverter.
Want to know what your finca needs? Request a fixed quote: free site survey and a written proposal within 24 hours. Read more on our [off-grid solar page](/instalacion-solar-aislada) and in the [off-grid FAQ](/faq#off-grid).
