Location and brief
A private house in Sopot, 45 km south of Belgrade. Three-phase supply, a standing-seam metal roof, and a separate car carport on the plot.
The owner wanted to cover daytime consumption with his own generation and to gain a backup for grid outages: the fridge, the pump and the lights had to keep running without a petrol generator.
Two constraints shaped the configuration.
- One house roof is not enough. Twenty-eight 450 W panels need more area than a single roof plane offers.
- The seam must not be drilled. Every hole in a metal roof leaks sooner or later and voids the warranty on the roof covering.
- Backup power was required. A grid outage must not stop the house — daytime savings alone were not enough for the owner.
Solution: the array on two planes
We split the panels into two groups: part of them went on the house roof, the rest on the roof of the car carport.
- No holes in the roof. Both roofs are standing-seam, so the rails clamp straight onto the seam. No drilling, no sealant, and the warranty on the roof covering stays valid.
- Two groups, two MPPT trackers. The house roof and the carport face different directions. The DEYE inverter tracks each group separately, so a cloud or shade over one part of the array does not pull down the output of the other.
- The carport works on both sides: panels above, covered parking below.
- The array grew during installation. We started with 22 panels and added six more. The 15 kW inverter accepts up to 19.5 kW of PV, so the extra modules fitted in without replacing equipment or reworking the scheme.
- Half the array is serviced from the ground. The carport panels are cleaned and inspected without climbing onto the house roof.
Installed equipment
PV array
- 28 Risen RSM108-10-450BNDG panels of 450 W each
- Total array power: 12,600 W
- Module efficiency 22.1%, 108 half-cells, full black finish
- Manufacturer warranty 15 years, design life 30 years
Mounting for standing-seam roofs
- Aluminium seam clamps, rails, end clamps and mid clamps
- Installation runs without drilling the roof covering
- The same mounting system on both roofs — the house and the carport
DEYE GB-SL15K All-in-One hybrid inverter
- Rated power: 15 kW, three phases, 380/400 V
- UPS mode: 15 kW — when the grid drops, the house keeps running
- Maximum PV input: 19.5 kW, leaving headroom for expansion
- Off-grid peak power twice rated for 10 seconds — enough for the inrush current of a pump or an air conditioner
- 2 MPPT trackers — these are what let the array be split across two planes without losses
- Maximum efficiency 97.6%, IP65 enclosure
- Inverter, battery block and power distribution unit sit in a single cabinet — no separate plant room needed
Battery storage
- 4 DEYE GB-SL 4.09 lithium modules — 16.36 kWh in total
- LiFePO4 chemistry, 6,000+ cycles at 70% retained capacity
- Power distribution unit (PDU) and battery base
Electrical works and installation
- Distribution board with a solar generation meter, RCD and breakers
- Surge protection on the AC and DC sides
- Inverter wiring and programming, current sensors, earthing
- Internet connection and monitoring setup
How the system works
- During the day the panels power the house directly and the surplus goes into the batteries.
- In the evening and at night the house draws on the stored 16.36 kWh: lights, appliances, fridge, pump, routers.
- During a grid outage the inverter switches the house to island mode at 15 kW — there is no need to pick what stays on.
- At any moment the app shows output per panel group, battery charge and consumption per phase.
Timeline
- Advance payment for equipment — 25 June 2026
- Delivery of the inverter, panels and protection devices — 18 July 2026
- Mounting and panel installation on both roofs — 25 July 2026
- Boards, cable runs and inverter installation — 25 July 2026
- Commissioning — 25 July 2026
One month passed from the advance payment to a working system, and the installation itself took 7 days.
Warranty
- Risen panels — 15 years
- DEYE inverter and battery modules — 10 years
- Base and power distribution unit — 5 years
- Installation works — matching the manufacturer warranty period
Cost
Turnkey project — from €15,800 incl. VAT. The price covers equipment, delivery from the customs terminal in Belgrade, standing-seam mounting hardware, electrical materials, installation, programming and commissioning.
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Every project is unique. This solution was designed individually for the requirements and conditions of this particular site.
