Townhouse Solar - Mijas Costa
5kW east-west split solar on a flat-roofed Mijas townhouse — dual-orientation array extends production hours where no south pitch exists, with Solar iBoost capturing surplus before grid export.
By Ben Hayden
Project Overview
The Challenge
The Mijas Costa townhouse had 62m² of total roof area — the south-facing slope was only 34m², shared with the adjacent townhouse via a party wall. The community of owners had approved individual solar installations but stipulated panels must be flush with the existing roof pitch and not extend beyond the terrace parapet. With limited premium roof area and partial shading from a neighbouring development's mature pine trees creating 25-30% shading on the lower third of the south slope between 09:00-11:00, the challenge was to maximise production from a constrained site while keeping total installed cost within the client's €10,000 budget.
The Solution
7kW solar system for terraced townhouse with limited roof space. Optimized panel layout maximizes production.
Technical Specifications
- 18 x 400W Q.PEAK DUO-G9 panels
- Fronius Primo GEN24 6.0 Plus inverter
- East-west split array configuration
- Shadow optimization technology
- 20-year product warranty
Our Installation Process
Site Survey & Shadow Modelling
We used a Solmetric SunEye and Solargis assessment to model annual irradiance at each panel position on the south slope. The lower three rows received 72% of the incident irradiance due to morning pine shading. We specified Q.PEAK DUO-G9 half-cut cell panels — half-cut technology splits each panel's cells into two independent circuits, so shading on the lower half doesn't affect the upper half's output. This technology makes the Mijas Costa installation perform as if 14 unshaded panels were installed rather than 18 partially-shaded ones.
East-West Array Configuration for Extended Hours
With the south slope partially constrained, 6 of the 18 panels were positioned on the terrace parapet east-west at 15° tilt. This east-west split extends productive generation from 07:00 to 19:30, better matching the retired owner's all-day home consumption profile. The Fronius Primo GEN24 has two independent MPPT inputs, allowing the south and east-west arrays to track their respective peaks independently.
Community Compliance & Boletín Eléctrico
The installation design was submitted to the community administrator with photographs confirming panels were flush with the roof slope and no parapet was exceeded. The Boletín Eléctrico was issued by our REBT-authorised electrician on the day of commissioning, and CAU registration with Endesa was completed within 2 weeks, enabling immediate surplus export credit on the next monthly bill.
Solar iBoost Monitoring Setup & Net Compensation Enrollment
A Solar iBoost immersion controller was installed alongside the inverter — diverting surplus solar generation directly to the hot water cylinder during periods when the battery is full and self-consumption is satisfied. This eliminated the gas boiler's role in daytime hot water heating during summer months. The Solax monitoring portal was configured on the owner's smartphone: the real-time dashboard shows solar generation, battery charge level, grid import/export, and household consumption in five-minute intervals. An automatic alert triggers if daily generation falls below 50% of the expected seasonal value for more than 2 consecutive days — enabling rapid fault detection without manual monitoring. The townhouse was enrolled in Endesa's PVPC net compensation billing, and the first compensation credit appeared on the invoice issued 34 days after CAU activation.
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 Mijas 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
- Mijas, Málaga
- Completed
- December 2025
- Service
- Solar
- Author
- Ben Hayden
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