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off-grid and hybrid system regulations

What are the regulation in your area/country for grid connected off-grid systems ?

  • No regulation. Can install freely as I want.

  • I have to follow this regulations/rules (see my post below )

  • I need a permit from utility

  • I need a plan made by a registered electric engineer


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mrzed001

Voice of reason
Joined
Apr 10, 2020
Messages
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Location
Hungary - EU
I think I live in an off-grid stone age here in the middle of the EU. ?

Really, the utility companies (and government) is stuck 10-20 years ago.
They are stuck in the separated off-grid (an inverter can only have DC-battery and AC out connection) and the AC coupled hybrid era (need extra PLC to go off-line).
And the regulations are based on that.
Like noone ever saw an all-in-one inverter like the MPP Solar/Growatt.

So what I am asking is: What are the regulation in your area/country for grid connected off-grid systems ?
- Do you need a permit for it from the utility company?
- Do you need a plan made by a registered electric engineer?
....
 
I don't really know much about it (I'm in the USA) but based on what I've read from others here in the forum, and heard from some of my neighbors who 'net meter', If your hybrid inverter is only capable of being a battery charger for your battery bank (not technically grid-tied, not back feeding, or referred to as 'net metering'), then there is no complex regulation other than normal electrical code law based on the NEC and any local city / county codes. Your battery charger is essentially just an appliance, only capable of drawing power one-way off the AC grid, to be able to charge your battery, or pass AC through to your main panel.

But if you are grid-tied / net metering (back feeding power back onto the grid), there is a bunch of more complex rules based on UL1741 (and Rule 21) that must be followed as well to ensure that your system is safe and prevents back feeding power when the utility grid goes down (amongst other things). In that case, I'm sure there is requirement to register or get a permit from the utility company, as they would obviously need to know how to pay you for back feeding power to their grid.
 
I don't really know much about it (I'm in the USA) but based on what I've read from others here in the forum, and heard from some of my neighbors who 'net meter', If your hybrid inverter is only capable of being a battery charger for your battery bank (not technically grid-tied, not back feeding, or referred to as 'net metering'), then there is no complex regulation other than normal electrical code law based on the NEC and any local city / county codes. Your battery charger is essentially just an appliance, only capable of drawing power one-way off the AC grid, to be able to charge your battery, or pass AC through to your main panel.

But if you are grid-tied / net metering (back feeding power back onto the grid), there is a bunch of more complex rules based on UL1741 (and Rule 21) that must be followed as well to ensure that your system is safe and prevents back feeding power when the utility grid goes down (amongst other things). In that case, I'm sure there is requirement to register or get a permit from the utility company, as they would obviously need to know how to pay you for back feeding power to their grid.

I am interested about all the regulation from all parts of the world about off-grid inverters :)


Many MPP Solar inverters (that can be used without a battery) mix the generated solar power into the grid power.
The grid goes through the inverter, and the inverter like a grid-tie inverter feeds to that line.
In the AC in part is a limiter (current sensor) and that makes measurements. Inverter based on that generates power but always less that the demand on the AC out port.
This is the scheme of an inverter (this is a Victron, but they work almost the same ... like MPP Solar MGX, EASun SML II, ...)

Victron3.jpg


"Technically" can say it is a grid-tie (with limiter) & off-grid inverter (in one). Not a hybrid, can not feed to the grid (limiter does not allow it).

Anyone has any regulation for this type of inverters ?
 
"Technically" can say it is a grid-tie (with limiter) & off-grid inverter (in one). Not a hybrid, can not feed to the grid (limiter does not allow it).

Anyone has any regulation for this type of inverters ?

I would be very concerned that it could backfeed just enough to electrocute a lineman, without the limiter seeing that as export.

I think (but don't know) that for the US this should require UL1741 anti-islanding. If island is detected, but stop driving, or disconnect from grid.
 
I would be very concerned that it could backfeed just enough to electrocute a lineman, without the limiter seeing that as export.

I think (but don't know) that for the US this should require UL1741 anti-islanding. If island is detected, but stop driving, or disconnect from grid.

The well known MPP Solar LV6548 works like this (from its manual):


MPP_Solar_LV6548_schema.png


 
The well known MPP Solar LV6548 works like this (from its manual):


View attachment 79252

The LV6548 also indicates on its product page that it is: "UL1741 compliance (TUV certified)"

So theoretically it shouldn't allow any kind of AC power to go in reverse direction on the AC input bus since it's not designed as a back feeding net-metering enabled device (I would think anyways). It seems it should have the safety precautions built into it... So theoretically if grid goes down, it would not allow voltage potential to go back out on the input.
 
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