ᐅ New Carport: Should I install two high-voltage outlets and size conduit for a future photovoltaic system?

Good morning everyone,

We built our single-family home with solid construction in 2017 and are generally very satisfied.

Our only regret is that we didn’t install a high-voltage cable to the outside at that time. Since we will be adding a carport right next to the utility room this summer, and the paving will be reopened, we want to use this opportunity to fix that and lay additional cables under the paving.

Here’s what we plan to do (at some point in the next few years), and I’d like to know what size cables or conduits would be sufficient:

1. Wallbox -> planned right next to the utility room, 11 kW capacity....the straight-line distance is about 2 m (6.5 feet) from the house wall, so I think dimensioning the cable for 10 m (33 feet) length would be safe...the electrician can always shorten it during installation.

2. High-voltage cable to the garden -> we are considering possibly setting up a garden sauna in the future. This cable would be much longer, about 40 m (131 feet), and the heaters have a power rating between 6.8 and 9 kW.

3. Photovoltaic system on the carport -> flat roof with about 36 m² (387 square feet) surface area (photovoltaic load up to 42 kg/m² (8.6 lb/ft²) is already accounted for in the structural design, metal carport). We want to lay at least the conduits under the paving in advance. Ideally, we would also lay the cables at this stage, but I think that depends heavily on the system used, right? I read in the forum that UV-resistant (flexible) plastic armored conduit in M32 size or preferably two would be ideal. Can these be pulled directly under the paving to the house entry point? Also, we plan to choose a system with a battery storage because of the wallbox, since charging will mostly happen overnight.

Is it possibly feasible to run cables for both the wallbox and the photovoltaic system through a shared conduit?

It would be ideal if we could route the cables through our multi-utility duct. One entry point is still free, but that depends on the opening in the paving...otherwise we would need a wall penetration.

I would really appreciate your advice on which cable sizes would be sensible here, so that we don’t regret missing something later on.

Thanks!

Just use a 15mm (0.6 inch) HT pipe. It’s affordable and easy to handle. There’s plenty of space under the paving,

hampshire schrieb:

Just use a 15mm (5/8 inch) HT pipe. It’s affordable and not fiddly. There’s plenty of space under the paving,

So a 15mm (5/8 inch) pipe for the photovoltaic system? Somehow that seems a bit... small...

Do you perhaps also have a tip for the high-voltage cables? Is NYY-J 5x6mm² (5x0.01 inch²) sufficient, or should I size up to 10mm² (0.016 inch²)?

Nemo2002 schrieb:

Do you perhaps have a tip for the heavy-duty power cables? Is NYY-J 5x6mm² sufficient?

For an 11kW charging station, you generally start with 5x2.5mm² (depending on length). This will easily be enough for your distance (this is the minimum cable size for my station). However, my employer insists on 5x4mm² since I get reimbursed for the electricity used for the company vehicle.
For the sauna and the cable length, the sizing should be calculated.

Wouldn’t it be better to install a sub-distribution board in the carport?

Run a separately fused cable from the main distribution board (before the RCD) to the carport and install a new RCD there. Use a 5x16mm (5x0.003 in²) cable from the main distribution board to the carport. From there, you can power the wallbox, garden sauna, etc., without having to go inside the house every time.

I’ve installed 5x16mm (5x0.003 in²) cable in my garage. That should be sufficient.

gmt94 schrieb:

Wouldn’t it be better to install a sub-distribution board in the carport?

Run a separately protected cable from the main breaker panel (before the RCD) to the carport and install a new RCD there. Use a 5x16mm (5x0.021in²) cable from the main panel to the carport. From there, you can operate the wallbox, garden sauna, etc., without having to go into the house every time.

I installed 5x16mm (5x0.021in²) cables in my garage, and that should be sufficient.

I would prefer to work without a sub-distribution, since the carport is open and honestly I don’t see a good solution for installing a sub-distribution board where everyone could access it...

@nordanney: Thanks, I think 4mm² (4.9 AWG) would really be the minimum, and maybe better to go up to 6mm² (6.4 AWG) just to be safe... For the sauna, I checked the calculation once and came up with a 3mm² (3.3 AWG) cable for a 9 kW heater at 400 V with a 40-meter (131 feet) cable run... power factor (cos phi) 0.8...