Off-Grid Solar System - Estepona Hills
13.5kW off-grid solar with 30kWh LiFePO4 battery bank and diesel backup integration — eliminating daily fuel deliveries to a remote Estepona hillside finca 2.4km from the nearest grid connection.
By Ben Hayden
Project Overview
The Challenge: No Grid Connection — Endesa Extension Quote Exceeded €22,000
The Estepona hills finca had no grid connection and no realistic prospect of getting one: the nearest distribution line was 2.4km away and the Endesa quote for extension exceeded €22,000 — more than the property's annual running costs. The owners had been managing with a diesel generator running 6–8 hours per day, spending over €3,800 per year on fuel and servicing while dealing with the noise, pollution, and maintenance burden of a machine that wasn't designed for continuous residential use. The challenge was to design a complete off-grid solar system large enough to provide genuine year-round energy independence for the finca, including a pool pump, washing machine, and full household loads — with a diesel backup for extended winter low-sun periods only.
The Solution
13.5kW off-grid solar system with 30kWh battery storage and diesel backup for a hillside property. Available autonomy depends on demand, weather, battery state and backup operation.
Technical Specifications
- 30 x 450W Longi monocrystalline panels
- 30kWh LiFePO4 battery bank
- Victron MultiPlus II 48/10000 inverter
- Diesel backup generator integration
- Complete off-grid energy management
Our Installation Process
7-Day Load Audit & Solar Resource Analysis
We installed temporary data loggers on all major circuits for a full week to capture the finca's actual load profile across different times of day and seasons. Solar resource data from the PVGIS database was cross-checked against on-site measurements. The audit confirmed a daily demand of 22–35 kWh depending on season, and identified the pool pump and water heating as the largest single loads, both suitable for scheduling to solar peak hours.
Off-Grid System Sizing — Battery Bank Design
The 30kWh LiFePO4 battery bank was sized to provide 2.5 days of full autonomy at average consumption without solar input — sufficient to bridge Estepona's typical winter low-sun periods. The Victron MultiPlus II 48/10000 inverter was selected for its ability to handle the finca's high starting currents (pool pump motor, washing machine) while seamlessly managing the transition between solar, battery, and diesel generator.
Hillside Panel Array Installation
The 30-panel array was installed across two hillside faces with slightly different orientations to extend the productive hours window and reduce morning shading. Individual MPPT charge controller strings were configured for each face, allowing the Victron system to harvest maximum energy from each orientation independently. Panel mounting structures were designed for the sloped terrain using ground anchors rather than a flat-ground frame.
Diesel Generator Integration & Auto-Start
The existing diesel generator was integrated with the Victron system via an automatic transfer switch and configurable auto-start trigger. When battery state-of-charge drops below 20% (typically only in extended January–February cloudy periods), the generator starts automatically, charges the battery bank to 80%, and shuts down — reducing fuel use from 6–8 hours daily to approximately 20–40 hours per year. The Victron VE.Bus system monitors and logs generator run-time for maintenance scheduling.
Remote Monitoring & Client Handover
The Victron VRM (Voltage Remote Monitoring) platform was configured to provide real-time visibility of the entire system: solar yield, battery state of charge, generator run-time, and load consumption. Alerts were set for low battery, generator failure, and inverter faults. The client was trained on the VRM mobile app and a commissioning report with all REBT documentation was provided.
Results
See the installation scope and equipment below; no financial outcome is promised.
Backed by Research
References for checking the proposed design. These sources do not certify this project's performance, savings, eligibility or commissioning records.
Estimate solar yield for the actual site
Annual generation depends on location, orientation, tilt, shading and system losses. An irradiance figure is not a guaranteed yield per installed kilowatt. State the assumptions and compare the estimate with the property's consumption.
European Commission — PVGIS ↗Check the applicable self-consumption arrangement
RD 244/2019 regulates administrative, technical and economic conditions for self-consumption. Export compensation is subject to the applicable arrangement and contract; exported energy is not automatically valued at the retail import price.
BOE — RD 244/2019 ↗Tax relief needs separate eligibility checks
Do not assume solar qualifies for an income-tax deduction or a standard municipal IBI discount. Check current AEAT conditions and the property's municipal ordinance, required evidence, dates and application process before including an incentive in a budget.
Agencia Tributaria — current tax guidance ↗Frequently Asked Questions
Related Services
LIT services in Estepona Hills directly related to this work.
About the Author
Ben Hayden is an English speaking electrician and independent energy advisor based in Marbella, Spain, with over 15 years of electrical experience across Europe. He provides independent energy and electrical checks for overseas property owners and managers across the Costa del Sol — helping clients cut electricity bills, navigate Spanish regulations, and make confident decisions on solar PV, heat pump, EV charger and battery storage projects. Ben advises in plain English on projects where the paperwork is in Spanish and the stakes are high. His writing has appeared in ExpatArrivals, The Olive Press, Euro Weekly News, BuildingTalk and pv magazine.
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Quote ConfiguratorProject Details
- Location
- Estepona Hills, Málaga
- Completed
- July 2025
- Service
- Solar
- Author
- Ben Hayden
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