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
€2,400 savings/year
Backed by Research
Solar PV performance figures and financial incentives are backed by Spanish law and independent research. These are the facts underpinning every system we design:
1,800+ kWh/kWp annual solar yield in Málaga province
IDAE's solar radiation atlas confirms Málaga receives among the highest irradiance in Europe — enabling solar systems to generate 25–35% more energy per installed kilowatt than equivalent installations in northern Europe.
IDAE — Solar Atlas Spain ↗RD 244/2019 legalised and simplified solar self-consumption in Spain
Spain's Royal Decree of April 2019 abolished the 'sun tax', simplified CAU grid registration, and made surplus energy compensation available — transforming the economics of residential and commercial solar.
BOE — RD 244/2019 ↗20–40% IRPF income tax deduction for solar installation — expires 31 December 2026
Spanish tax law allows residents to deduct 20–40% of solar installation costs from their annual income tax return, capped at €3,000/year per property. This incentive is time-limited and currently expires at the end of 2026.
Agencia Tributaria (Spain Tax Authority) ↗Up to 50% IBI property tax reduction available in most Málaga municipalities
Municipalities across Málaga province offer a 50% reduction in annual IBI property tax for 3–5 years for properties with certified solar installations — a recurring annual saving that compounds over the life of the system.
Diputación de Málaga ↗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.
Want a similar project?
Free consultation and no-obligation quote for Costa del Sol properties.
Quote ConfiguratorProject Details
- Location
- Mijas, Málaga
- Completed
- December 2025
- Service
- Solar
- Author
- Ben Hayden
