Questions with AC Coupled System Design and Power Company Requirements

**nwdiver** · 08-05-2019, 03:55 PM

Originally posted by StarLord

My biggest concern is my use of one 10000 watt inverter may make AC coupling prohibitavily expensive. I saw a small footnote or mention on the Mangnasine inverters that the wattage of the inverters should be 10% above the grid tied inverter. Is this true? It kind of makes sense as the inverter would be trying to push 10000 watts through a 4000 watt inverter during peak times and probably wouldent end well.

I've not done this myself yet but I believe you can limit the output of your SolarEdge inverter. Also not sure what kind of access you would need to perform this. So during a power outage if you want to AC couple your HD Wave to your Magnasine you can go set your HD Wave to limit its output to ~4kW. My understanding is that some installers actually stock only 7.6kW inverters to streamline logistics and will cap the inverter to allow them to use it on a lower amp circuit.

Here are instructions on how to change the power limit. Appears that you can change this it any value from 0-100%. You would need to log in locally with 'Setapp'

**ButchDeal** · 08-05-2019, 06:01 PM

Originally posted by StarLord

Good Morning Everyone,

I am currently planing out a Grid Tied Solar PV System and was seriously contemplating adding in batteries at a later date with the goal of emergency backup (Hurricane area in Florida) and self consumption as required by my local electric company (JEA).

Currently planned designed is:
30x 335 watt Panasonic HIT (10,050 watt DC) Roof mount, 18 Panels on South, 12 Panels facing East due to space limitations.
1x SE10000HD SolarEdge Inverter.
Inverter would be wired to an outside disconnect, then to a 60amp breaker inside the main load center for the house.

Our electric company offers a $4,000 rebate for a home battery system given certain conditions are met. The pertinant one is:

"Eligible battery systems must meet the minimum requirements of a 6 kWh usable capacity rating and a warranty of at least 10 years or 5,000 cycles,
with one cycle being defined as a full discharge. The system must also be programmable to operate in self-consumption mode."

When I started on this journey I had intended to just use a Tesla powerwall, but recently started looking into other solutions and wondering if my initial design may be flawed.

My biggest concern is my use of one 10000 watt inverter may make AC coupling prohibitavily expensive. I saw a small footnote or mention on the Mangnasine inverters that the wattage of the inverters should be 10% above the grid tied inverter. Is this true? It kind of makes sense as the inverter would be trying to push 10000 watts through a 4000 watt inverter during peak times and probably wouldent end well.

Since you have so much facing east and with a DC coupled system you would have almost no clipping so you might consider using the StorEdge SE7600 with LG RESU10H. It would be more efficient than AC coupled, and you would have more control over the self consumption/ backup use.

**ButchDeal** · 08-05-2019, 06:02 PM

Originally posted by nwdiver

I've not done this myself yet but I believe you can limit the output of your SolarEdge inverter. Also not sure what kind of access you would need to perform this. So during a power outage if you want to AC couple your HD Wave to your Magnasine you can go set your HD Wave to limit its output to ~4kW. My understanding is that some installers actually stock only 7.6kW inverters to streamline logistics and will cap the inverter to allow them to use it on a lower amp circuit.

Here are instructions on how to change the power limit. Appears that you can change this it any value from 0-100%. You would need to log in locally with 'Setapp'

This is not really approved for this type function as well as being very complex to set up and preventing automatic transfer for backup.

**StarLord** · 08-05-2019, 07:59 PM

Originally posted by ButchDeal

This is not really approved for this type function as well as being very complex to set up and preventing automatic transfer for backup.

Yeah was thinking the same, would be no way to make it automatic without possibly using scripts and having a delay in switching to backup.

**nwdiver** · 08-05-2019, 08:18 PM

Originally posted by StarLord

Yeah was thinking the same, would be no way to make it automatic without possibly using scripts and having a delay in switching to backup.

True.... but it should work in a pinch. Depends on your budget and use case. That's how my backup works. It's on an interlocked generator breaker. Not automatic but much cheaper.

**ButchDeal** · 08-05-2019, 08:25 PM

Originally posted by nwdiver

True.... but it should work in a pinch. Depends on your budget and use case. That's how my backup works. It's on an interlocked generator breaker. Not automatic but much cheaper.

Op would not get the incentive as it couldnt load shed and backups would have to be manual with interruption

**StarLord** · 08-05-2019, 08:26 PM

Originally posted by ButchDeal

Since you have so much facing east and with a DC coupled system you would have almost no clipping so you might consider using the StorEdge SE7600 with LG RESU10H. It would be more efficient than AC coupled, and you would have more control over the self consumption/ backup use.

Thought about this as well, but with the JEA requirement for a separate disconnect for the battery and the inverter I dont think this setup is even possible. From the JEA checklist

"The external manual AC disconnect switch for the generation system and, if energy storage is included, the separate external manual AC disconnect
switch for the energy storage system must be in the open position (OFF) until JEA inspects the system..."

Seems a bit nuts to require two disconnects or even one disconnect for that matter when they have to be within 5 feet of the service meter. Simply pulling the meter or turning off the main AC disconnect for the house will have the same effect as switching off external disconnects for the generation system as far as the grid is concerned. Just a way to make things more difficult for going solar? In my case it requires another 80ft of wire runs and extra conduit penetrations to the outside, total pita.

**ButchDeal** · 08-05-2019, 09:54 PM

Originally posted by StarLord

Thought about this as well, but with the JEA requirement for a separate disconnect for the battery and the inverter I dont think this setup is even possible. From the JEA checklist

"The external manual AC disconnect switch for the generation system and, if energy storage is included, the separate external manual AC disconnect
switch for the energy storage system must be in the open position (OFF) until JEA inspects the system..."

Seems a bit nuts to require two disconnects or even one disconnect for that matter when they have to be within 5 feet of the service meter. Simply pulling the meter or turning off the main AC disconnect for the house will have the same effect as switching off external disconnects for the generation system as far as the grid is concerned. Just a way to make things more difficult for going solar? In my case it requires another 80ft of wire runs and extra conduit penetrations to the outside, total pita.

Of course you can have a second AC disconnect with a DC coupled bimodal system. The inverter will have two AC connections, one to the grid side and one to the emergency ( backup ) panel.
You might be able to avoid the one if you ask if you can use a firmans disconnect switch which will shut down the inverter when pressed ( optional equipment switch from solaredge)

**StarLord** · 08-06-2019, 09:25 PM

Thanks for the replies everyone, this really got me thinking about my entire setup. Doing some more digging but looking like if I were to go the battery route it would be best to drop solaredge altogether, they just seemed the simplest for DIY and grid tied. Taking a hard look at Sol-Ark now, their system seems really versatile just lose the panel level monitoring. Think a 10kw inverter may be over kill for my South / East array setup and the 8k they offer would be perfect without much if any clipping. But I may be deep into the weeds now and overthinking everything

**paulcheung** · 08-07-2019, 12:32 AM

Originally posted by StarLord

Thought about this as well, but with the JEA requirement for a separate disconnect for the battery and the inverter I dont think this setup is even possible. From the JEA checklist

"The external manual AC disconnect switch for the generation system and, if energy storage is included, the separate external manual AC disconnect
switch for the energy storage system must be in the open position (OFF) until JEA inspects the system..."

Seems a bit nuts to require two disconnects or even one disconnect for that matter when they have to be within 5 feet of the service meter. Simply pulling the meter or turning off the main AC disconnect for the house will have the same effect as switching off external disconnects for the generation system as far as the grid is concerned. Just a way to make things more difficult for going solar? In my case it requires another 80ft of wire runs and extra conduit penetrations to the outside, total pita.

For an AC Coupled system, pulling the meter out don't turn off the solar power. so for the safety of the fire fighters you need a disconnect near the meter so they can turn it off in the event of fire.

Questions with AC Coupled System Design and Power Company Requirements

Questions with AC Coupled System Design and Power Company Requirements

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