I am planning for an installation of a a solar system. I have a garage with ample space and would rather it be installed there than in the house. My garage is connected to the main electricity supply and has its own DB. Does the inverter and batteries have to be near the main DB? Can they connect the wiring to the garage without having to install additional cabling from the house to garage?

It should be fine. As long as the cable that is currently connecting the garage DB and the main DB is adequately sized. At bare minimum it should be a 4mm2 cable. If you are planning on putting an inverter more than 7kw then it should be 6mm2. Anything more than 10kw will probably need a 10mm2 cable.

It does not need to be near the main DB also.

For a 5 kW inverter bypass 5kw + 3 kw AC charging (total 8 kw incoming) then input cable = 6 mm² is the right, conservative choice. The output cable from the inverter (only 5 kW) can be 4 mm².

For 8 kW and 10 kW inverters with charging, typically up to 10 mm² or 16 mm² input conductors respectively, once ac chargers is configured currents can be at or above ~50–60 A.

Distance between main db and sub db also needs to be considered.

Edited September 8, 2025Sep 8 by TaliaB
Rectified db not bd

6 hours ago, Vin said:

My garage is connected to the main electricity supply and has its own DB. Does the inverter and batteries have to be near the main DB? Can they connect the wiring to the garage without having to install additional cabling from the house to garage?

Keep in mind that all the power used in your house will have to travel back to the main DB in the house, as your inverter will now be providing the power that used to come from the grid. So, the PV panels would feed the inverter/MPPT in the garage (around 350V - 400V DC), and the inverter will charge the batteries with DC (48V - 56V DC depending on your system) and also supply the AC (230V) to the house. If the house was originally wired from the incoming grid to the main house DB to the secondary garage DB (with the main switch and earth leakage switch in the main DB), then power will likely now flow from the inverter in the garage to the house and back to the garage DB (for whatever loads you have in your garage) - so, as stated by @TaliaB and @Denns you will most likely need to replace the garage DB to house DB cabling with larger wire. Also keep in mind that you will probably need to install an export limiting CT coil where your grid power enters your main DB if your hybrid inverter requires this, so ideally the inverter and main DB should not be too far apart.

Good luck with your installation, and keep us updated 😊

1 hour ago, TaliaB said:

For a 5 kW inverter bypass 5kw + 3 kw AC charging (total 8 kw incoming) then input cable = 6 mm² is the right, conservative choice. The output cable from the inverter (only 5 kW) can be 4 mm².

For 8 kW and 10 kW inverters with charging, typically up to 10 mm² or 16 mm² input conductors respectively, once ac chargers is configured currents can be at or above ~50–60 A.

Distance between main db and sub db also needs to be considered.

Yep. For the typical install that’s about right. My inverter has only got 2 cables coming to it. One for the essential load and a second for non essential.

I have no cable for the AC input as the inverter is only set to charge from PV. It’s done that way as I have plans to get disconnected and have been running fine for the last 5 months with no issues.

He would definitely need a bigger cable on the input. I have 4mm2 on both outputs.

1 hour ago, HennieL said:

Keep in mind that all the power used in your house will have to travel back to the main DB in the house, as your inverter will now be providing the power that used to come from the grid. So, the PV panels would feed the inverter/MPPT in the garage (around 350V - 400V DC), and the inverter will charge the batteries with DC (48V - 56V DC depending on your system) and also supply the AC (230V) to the house. If the house was originally wired from the incoming grid to the main house DB to the secondary garage DB (with the main switch and earth leakage switch in the main DB), then power will likely now flow from the inverter in the garage to the house and back to the garage DB (for whatever loads you have in your garage) - so, as stated by @TaliaB and @Denns you will most likely need to replace the garage DB to house DB cabling with larger wire. Also keep in mind that you will probably need to install an export limiting CT coil where your grid power enters your main DB if your hybrid inverter requires this, so ideally the inverter and main DB should not be too far apart.

Good luck with your installation, and keep us updated 😊

CT-clamp would be an important consideration in choosing the location, relative to the main DB, that said, there's also the option to use an Eastron Meter if distance is too far, am sure @TaliaB and @Denns or your installer will advise. Once you decide what are your essentials and non-essential loads and if you wish to export or not to export or play around with battery State of Charges (SoC), Time of Use settings etc for supplying to non-essential loads. The rest has been well advised.

Thanks all for the informative replies. I will get the installer to check existing cabling.

On 2025/09/08 at 8:01 PM, HennieL said:

you will most likely need to replace the garage DB to house DB cabling with larger wire. Also keep in mind that you will probably need to install an export limiting CT coil where your grid power enters your main DB if your hybrid inverter requires this, so ideally the inverter and main DB should not be too far apart.

@HennieL is spot on above. @Vin How far is your main db from the sub db in your garage? @Moffat I have done installations where the ct cable runs back to the main incoming feeder between 15~ 20 meters with good quality Cat 6e or Cat7 cable for Sunsynk Deye and Victron Multiplus 2 using Carlo Gavazzi energy meter. I would personally while rewiring the sub db install a 10mm² feeder from the main db and run 6mm² back to the main( essential curcuits) db for future expansion.

Edited September 11, 2025Sep 11 by TaliaB
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