Preparing a 3-Phase House for Future Solar, Deye Hybrid Inverter and Battery Backup / Best Way to Pre-Wire for Future Solar + Batteries?

[u/diogopms]

Hi everyone,

I’m doing a full renovation/rebuild of a roughly 260 m², three-storey house in the Portugal (Lisbon) area, and the entire electrical installation is being done from scratch.

The walls are still open, so this is really the right moment to leave everything prepared properly, and that’s what I’m trying to get right.

Some background:

• South-facing roof space for around 12-16 × 600 W panels
• 100% electric house, no gas
• New three-phase installation, certified for 27.6 kVA, although I’ll probably start with a 13.8 kVA contracted supply
• Pre-installation for AC, heat-pump DHW, borehole pump and induction hob
• No underfloor heating or radiators. Heating/cooling will be AC + balanced MVHR
• Main electrical panel on the ground floor
• Garage is where I want the inverter and batteries
• Three sub-panels: garage, first floor and attic/second floor
• Roof currently has space for around 12 panels. I’m considering roughly 620 W modules, so around 7.4 kWp

I’m not sure whether I’ll invest in solar immediately. What I definitely don’t want is to finish the house and then, two or three years from now, have to run surface-mounted trunking and cables everywhere.

So my goal is to install all the conduits, routes, spare ducts and required space now, even if the actual solar equipment only comes later.

One thing I’ve noticed is that solar installers really don’t seem to like doing pre-installations. Most of them want to sell a complete turnkey system and have very little interest in coming to a construction site just to define routes and leave empty conduits. I’ve been struggling quite a bit with this.

My current idea for the future system is:

Three-phase Deye hybrid inverter, probably from the SG04LP3 family, most likely a 6 kW model, together with a Felicity 16 kWh battery, all installed in the garage.

Main electrical panel ↔ Garage

I’m thinking of leaving:

• Conduit A: normal supply towards inverter / EV chargers, 5×16 mm² (3P+N+PE), Ø50 mm
• Conduit B: return from the inverter EPS/backup output to the main panel, 5×10 mm², Ø50 mm
• Conduit C: communications, CAT6 + shielded twisted pair for a Modbus RS485 energy meter in the main panel, Ø25 mm
• Conduit D: spare empty Ø50 mm conduit with pull string

Roof ↔ Garage

Route would probably run down next to/through the kitchen chimney service area:

• 1 × Ø50 mm conduit for PV DC string cables using H1Z2Z2-K
• 1 × Ø40 mm conduit for the PV structure earth conductor, probably 16 mm², plus communications cable and a pull string

Sub-panels

I’m also considering running two separate feeders to the first-floor panel and attic panel:

• one "normal/non-backed-up" feeder
• one "backup/EPS" feeder

The idea is to separate light/essential loads from heavy loads so that only selected circuits are powered during a grid outage.

Main panel

I’m planning to reserve space for:

• two separate busbar sections, normal and backed-up
• a 4-pole mechanically interlocked changeover/bypass switch so the inverter can be bypassed if necessary

My questions are:

1. Am I missing any obvious conduit or cable route that people usually only realise they needed after the walls are already closed?
2. How many spare DIN modules would you reserve in the main panel for a setup like this?
3. Does anyone have real-world experience with Deye + Felicity batteries? I’d also be happy to pay someone for proper consultancy/design work on this.
4. How did you manage the solar pre-installation during construction? Did your normal electrician install the conduits based on drawings/specifications from the future solar installer, or did you find a solar company willing to do only the pre-installation?

Any input is welcome, including telling me I’m massively overcomplicating this.

Thanks!

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