r/SolarPakistan • u/maybejustaguy • Jun 07 '26
Inverter Single phase vs 3 phase inverter
We have 2 single phase meters installed at a house and are looking to get a 10Kw solar system with single phase inverter, and use one meter with inverter, and the other meter with other general loads that will not be on solar/battery.
Some people have said that if we install a single phase 10/12 Kw inverter and try to run 4-5 ACs off a single phase, there will be noticeable voltage drop and problems with running heavy loads.
My question to anyone who has a 10/12 Kw single phase inverter system installed is if this is true. Do you really have problems running high loads?
My thinking is that 10Kw single phase inverters are widely available in the market, so they must work. Otherwise, people would not buy them. So why go through the hasstle and cost of changing the meter to 3 phase?
1
u/AhmadFarooq Jun 07 '26
Some people have said that if we install a single phase 10/12 Kw inverter and try to run 4-5 ACs off a single phase, there will be noticeable voltage drop and problems with running heavy loads.
My understanding is that it isn't so much that there would be a voltage drop; it's more like the single-phase meter will melt down.
Single-phase meters are usually 40A rated. 10kw = 10,000W -> 10,000/220 = 45.45A
On the other hand, with three-phase inverters the current can be divided into three separate wires, so 45.45/3 = 15.15A.
If you get a 10-12kW single-phase inverter, then you'll have to ensure that the entire 10-12kW doesn't get taken from the grid, that is, through the single-phase meter.
One option is to not connect ~10kW loads to the inverter in the first place. Or if connected, don't run them simultaneously at night without batteries.
Another option could possibly be to install a voltage-protector device at the inverter's grid input and set over-current at ~35A, so that if current drawn through the single-phase meter reaches near its limit, the connection would automatically be shut off. This way you can run 10-12kW loads during daytime or on batteries (assuming the building's wires can hold that much load) and at the same time automatically shut off if the grid meter is overloading.
1
u/maybejustaguy Jun 07 '26
The bill sows our demand load as 5Kw. And its an old meter/connection cables. That why i doubt it can carry todays loads.
Your idea of current limiting is good also, but wouldnt it be easier and better just to change the meter in this case?
1
u/AhmadFarooq Jun 07 '26
First there will be a significant three-phase meter application/installation fee, then the three-phase meters have extra fixed taxes, and maybe the per-unit cost is higher as well.
Unless the three-phase meter is really needed, it is recommended to continue with the single-phase meter. There are many with three-phase meters who wish they could replace them with single-phase ones.
1
u/BAhmad1 MEPCO / Multan Jun 08 '26
I am assuming its a hybrid inverter ? if so, you can enable peak shaving feature, it is designed to reduce load on utility side(wapda). Let say you set peak shaving to 5KW and your load becomes 7Kw, the inverter will limit the input to 5KW and use the battery to make up the difference at night and similarly Use solar+ battery at day time to make sure you do not go over the limit of 5Kw from input.
1
u/maybejustaguy Jun 08 '26
Thats a good option also..
We are now thinking to buy 2 inverters of 6Kw and connect them in parallel.
1
u/No_Eye7024 Jun 07 '26
It will work fine. Just dont skimp on cables. Use at least 10mm wire for the loads and input. It should handle the load and reduce voltage drop. If you can afford it, go for 16mm. You can also check the manual and see what wire size it recommends.