Paul B avatar image
Paul B asked

Should long distance wire runs from Solar panels be done in AC or DC?

Hi All

This is the first large household system that we have sold.

The main questions are the Aray wiring runs and were to place the grid tie inverters.

we have done plenty of single parallel and 3 phase installs onto boats and yachts but this has been relatively small solar wise ie max 5Kw of solar and this has then all been DC coupled so these have long runs from the string to the MPPT but this because we have HV Dc to a LV DC out

I have done my own house 5Kw AC coupled. and ESS so I think I am ok in that area. (plus this was 1 phase and the run was quite short)

we are splitting up the installation the DC Backup Inverters being 3 x 15KW 3 phase Quattro inverters we are doing ourselves and we are outsourcing the Solar installation to a external company inc up to 3 x Grid Tie SMA inverters 3 x 20Kw or similar we are having a local solar installer here do that part as they will be mountingb the panels on the roof etc .

I am having a discussion re the location that the 20kw Grid Tie Inverters. as I have my ideas and the solar installer has his, as its my sale and the end buck stops with me if there is a issue latter and I have asked them to do the solar install so , I can say what he will do to a point, but I need to know that I am correct and am not missing something. or its no big deal you can do it eighter way without any issue.

System install is

3 x 15Kw 48 volt quattros plus CCGX plus 40Kw LIPO Battery bank

1 x 30 Kw aray 100 mtrs from main distribution room

1 x 15Kw aray 50 Mtrs from main distribution room

New house and cables and conduct are being installed next week as needed

total array size 45Kw in the end

the Array sizes are in flux at the moment going from 15Kw to 45 depending on looks of the panels and the locations on the new Villa, so we may just wire the areas while we can and install the arrays latter when the customer is ready.

Again The main questions are the Aray wiring runs and were to place the grid tie inverters

So any suggestions re the below options would be apreciated.

Option 1 and How I see it being configured

I feel the Grid Tie Inverters should be mounted in a dry place as close to the panels array as posable as we will have 4 to 5 strings, and yes they will be high voltage at around 300 volts average running voltage but DC to the grid tie units, so to me as they are DC and we have multi strings its best to have the Inverter as close to the Panels as posable to reduce cable run DC Losses and then run one large 100 Meter 3 phase AC run to the Main distribution area were the Victron Quattros will be placed. carrying the one 3 phase 20Kw cable (The GT inverter would be mounted in a dry well ventilated area)

Option 2 what the SOLAR installer wants to do (not preferred by myself) but stand to be corrected here

They want to mount the Grid Tie Inverters at the main Distribution room and then run all the String cables being DC from the 20Kw array in separate runs all the way back to the main distribution board and then plug these strings into the Grid Tie Inverter there.

As this is Reasonably High DC voltage, I would have thought that the runs should be as Short as posable. Due to Losses sending DC over the 100 Mtr run, (let alone having 6 x separate DC cable runs.) where the AC run would be less of a loss plus only one large cable

So is option one the corret way or is option 2 or does it not matter in the real world,

keep in mind correct cable sizing is done for the option chosen that is.

Thanks for any insites Given.

MultiPlus Quattro Inverter Charger
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Usually the DC voltages on PV systems are much higher, from 400V up to 800V or 1000V max for most PV inverters, thus minimizing wire losses.

Also: usually one installation room is preferred for all high power components, climate controlled if necessary (ventilation might be enough).

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Pat Davitt avatar image
Pat Davitt answered ·


Below is a link to information on power transmission that should help you understand why using HVDC (High Voltage DC) is more efficient than AC transmission.


2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.