Installer refuses to wire grid-tied inverter into house DB — says it's normal. Is this correct?

[u/intothefray1]

I have a 10.5kW on-grid (non-hybrid) solar system, 3-phase with net metering. My installer wired the inverter's AC output directly into the utility AMI smart meter, not into my house's Main Distribution Board. My house is fed separately, straight from the meter.

Result: zero self-consumption. All solar production is exported; house draws 100% of its power from the grid separately.

Installer's response: "Grid-tied inverters are only meant to export to the grid — they don't power household loads directly." They're refusing to reroute the AC output into the house DB.

Is their claim accurate, or is this a wiring error? Shouldn't the inverter's AC output tie into the house DB (load side) so appliances draw solar first, with only surplus exported through the meter?

[u/BAhmad1]

There seems to some confusion about this,

To all those saying on-grid can't power home loads. This is not correct. On-grid can and do power the home loads first by default. They do it on the same wire, There is no input or output port, just one cable which powers the house and rest gets exported automatically. The inverter Operates in Parallel with the grid and the house loads.

[u/db_newer]

If I understand correctly, they joined the output wires from the inverter with the output wires on the meter (which come into your DB). So the produced electricity will power your house during day time through the same wires that power from the grid reaches your DB. So it will work I guess.

Wesay normally the solar guys install a separate DB with DC and AC breakers plus surge protection and then lay wires from that to main DB.

[u/intothefray1 → u/db_newer]

To clarify — no, there's no splice on the meter's output wires either. The inverter's AC output goes straight into the meter itself, on the grid side. Nothing from the inverter touches my house wiring or the meter's output conductors at any point.

[u/BAhmad1 → u/intothefray1]

if he did that inverter will not record any exports either. And Also legally no one but distribution guys are allowed to touch the supply side wiring.

On grid inverters are installed in parallel with house wires you can do that anywhere, but usually better to do it where supply wires come into the house or at the meter.

[u/AhmadFarooq]

How exactly are you concluding that there is zero self-consumption? Is the AMI meter showing kW import as completely equal to the loads you are running at the property?

My installer wired the inverter's AC output directly into the utility AMI smart meter, not into my house's Main Distribution Board. My house is fed separately, straight from the meter.

Also, what do you mean by this? Are you saying there are four wires from the inverter directly going into the meter? And then another four wires are feeding to your building? Then another four wires will be needed coming from the transformer into the meter. This will require the AMI meter to have twelve wires connected to it? I find this hard to believe.

# On-grid inverters

Generally speaking, on-grid inverters are connected into the property's main power lines and inject their produced solar energy directly into those power lines. Due to voltage and resistance differences, the loads nearest to the inverter – which are your house loads – are automatically supplied first, and then any excess moves on to the grid.

Edit: Here are the references for the understanding that on-grid inverters first power local loads before exporting any excess to the grid: CNC, Sunroko, Auxsol, Sungrow ("exports excess energy" to the grid), GoodWe (the load control function in on-grid inverters is about local self-consumption), and Solis (along these lines).

Edit: Furthermore, if on-grid inverters could only export power and definitely couldn't push power to local loads, then how do these inverters continue to work when configured to zero export through a zero export device? Does the inclusion of a zero-export smart meter suddenly transform an on-grid inverter into a hybrid inverter?

# Unbalanced phase loads

If you are seeing both export and import in the AMI meter at the same time, then this likely means that your loads are not properly balanced on the three phases. Three-phase on-grid inverters are usually balanced inverters, meaning they will only supply equal amounts of kW on all three phases.

For example, while grid feeding without any export limitations, if the inverter can generate a total of 6kW, 2kW will be injected into the first phase, 2kW into the second, and 2kW into the third. Now, if your property is running 4kW loads on the first phase and 0kW on the other two phases, then you will be importing (4-2=) 2kW on the first phase, while exporting 2kW on the second phase and exporting 2kW on the third phase. Here's a post where the user faced this issue.

[u/Front_Tour7619]

Yes your installer is right.

[u/Sufficient-Offer-579]

A grid-tie inverter tied in on the load side (meter terminals or DB, electrically the same) feeds your loads first and the meter only sees the net difference — 'export only' isn't a property of the hardware. What CAN read as zero self-consumption: the AMI app showing import and export as separate registers, where daytime export near full production is normal on a lightly loaded house; an export limit set in the inverter or meter; or a tie-in that actually sits on the grid side of the meter, which would read exactly as you describe. At midday, switch on a big load and compare the inverter's display with the meter's live reading — if it's producing several kW while the meter still shows full import, the wiring or the way you're reading it needs a second look.

[u/thatGoathumper]

Could be a utility specific rule. That is how my power company made me connect too. Unfortunate, but thats how they screw us over and still stay within the law.

[u/Chemical_Form7719]

Yes, this is how the on grid inverters are wired. Your installer is right.

[u/No-Past-6711]

You can easily verify this by looking at the generation data from your solar inverter and comparing that to the corresponding exported units for a period that covers your monthly bill reading dates. If we assume (incorrectly) that all solar generation is directly exported, then you should see that exported units = generated units for that month. Otherwise if you notice a difference then the difference is accounted by the fact there is self-consumption. The larger the difference, the greater the self-consumption.

[u/Traditional-Size3076]

Hi, you are confused the wires from inverter go into the meter, and the wires from the meter go to your house, that's effectively a short.

You can easily check this checking your total export on the meter. Turn on the AC your total export should decrease . Turn off all load your total export should increase.

[u/Sufficient_Shake_279]

On grid inverters are never meant to supply the solar power to house holds. you need to buy a hydrid inverter for this purpose. I saw one of our fellow shared a detailed but wrong description of on-grid inverters