StorEdge / LG Chem System

[andrew.tkelly]

Hi,

I'm presently designing a PV system w/ battery backup. I'm using a SolarEdge StorEdge w/ an LG Chem RESU10H (5kW, 9.3kWh).

Q1: Does the backup load center have to be MLO or MB type? Or does it not matter? SolarEdge gave me a sample single-line diagram where showed an MB type, so I thought it may have to be Main Breaker type. The backup load center will be about 30 ft away from the inverter.

Q2: Has anyone ever put a freezer or refrigerator on battery backup? If so, what was your experience?

Andy

 

[jaggedben]

Somewhere in the manual it says to install a 25A main breaker in the subpanel to protect the autotransformer. (Annoying, because it limits your subpanel options due to a hold down being required on that main.) One thing I've wondered is whether one can spec a higher rated autotransformer and go up to the 40A allowed by the backup load breaker that's internal to the inverter. It wouldn't get you more backup power, butnit would allow higher pass-through capacity when grid connected.

I'm currently working through my first installations and can't speak from experience on fridges. Butost fridges would only draw a few amps. Is there something about it that worries you?

 

[shortcircuit2]

Are the RS485 communication cables (600V rated) allowed to be installed in the same conduit as the AC/DC power wiring?

 

[jaggedben]

Are the RS485 communication cables (600V rated) allowed to be installed in the same conduit as the AC/DC power wiring?

Yes, if they're indeed 600V rated.

 

[SolarAlternativesDesign]

My refrigerator is on the backed up loads panel in my StorEdge system. I haven't had any problem with it.
The refrigerator starting power is 229W and the running power is 171W.
One thing to note about the StorEdge system is that the useable battery capacity is actually about 8.4 kWh AC, not the 9.3 kWh shown on the RESU10H data sheet. This is mainly because the data sheet capacity is based on discharge to 5% SOC but the StorEdge inverter cuts off inverting from battery at 13%.
Actual discharge test results for the SGIP incentive haven't been released yet and they might be a little lower.
Other battery backup systems also have actual capacity lower than the spec sheets according to the SGIP tech person I talked with, so this shouldn't be taken as relatively poor performance by SolarEdge/LG Chem.

 

[SolarAlternativesDesign]

Are the RS485 communication cables (600V rated) allowed to be installed in the same conduit as the AC/DC power wiring?

The RS485 shielded twisted pair 600V cable can be installed in the same conduit with the AC conductors. It's a little difficult to find a cable with those characteristics, but Belden B3106A works.
I don't know why there would be DC conductors in that conduit.
NEC 2014 690.31(B) states PV source circuits and PV output circuits shall not be contained in the same raceway, cable tray, cable, outlet box, junction box, etc. with conductors of other non-PV circuits or inverter output circuits unless the conductors of the different systems are separated by a partition.

 

[jaggedben]

...
I don't know why there would be DC conductors in that conduit.

For the battery it makes sense to run the communication cable with the circuit conductors. Those are DC. I've done that on the systems I've installed, and as it happens I've not run the meter RS485 with any AC conductors.

 

[SolarAlternativesDesign]

The StorEdge design as I got it has a 4-wire shielded twisted pair 600V cable from the inverter connection unit to the RESU10H. For this I used a Belden B7957A Cat 5e cable. This was a DC circuit but I didn't use an RS485 cable.
The connection from the inverter connection unit to the meter called for an RS485 shielded twisted pair 600V cable, which I ran in conduit with the inverter output circuit to a point near the service panel and SolarEdge meter. That was the AC circuit I referred to.

 

[shortcircuit2]

What classification do you give the RS485 wiring? Communication-article 800? Class 2 or 3 - article 725?

 

[GoldDigger]

What classification do you give the RS485 wiring? Communication-article 800? Class 2 or 3 - article 725?

Communication definitely refers to common carrier type systems (phone, cable, etc.), not to anything that carries data and therefore communicates. It may well be covered by limited power operation rules.

Sent from my XT1585 using Tapatalk

 

[SolarAlternativesDesign]

What classification do you give the RS485 wiring? Communication-article 800? Class 2 or 3 - article 725?

I took the cable type and size from the StorEdge installation manual. It doesn’t state the classification but, as you probably already know, the cable connects the SolarEdge meter (which measures current amount and direction between the utility meter and the main breaker) to the connection unit (which is used to manage power flow between PV, battery, service panel, auto-transformer and backed up loads panel).

 

[shortcircuit2]

So, it seems to be prohibited from being in the same raceway with power conductors by 800.133(A)(1)(c)

 

[jaggedben]

So, it seems to be prohibited from being in the same raceway with power conductors by 800.133(A)(1)(c)

How does it meet the article 800 definition of a communications circuit? There is no 'communications utility' involved.

 

[SolarAlternativesDesign]

Somewhere in the manual it says to install a 25A main breaker in the subpanel to protect the autotransformer. (Annoying, because it limits your subpanel options due to a hold down being required on that main.)

Jaggedben, are you referring to the breaker fastener in 690.10(E) and 408.36(D)? If so, I don’t think the requirement applies to grid interactive systems like StorEdge. 690.10(E) only applies to “multimode inverters in stand-alone systems” and 705.12(D)(5) repeats that the fastener of 408.36(D) doesn’t apply to utility-interactive inverters if listed and identified as utility interactive.

 

[SolarAlternativesDesign]

Does the listing of the StorEdge system extend to the installation manual direction on installing the cables? The manual clearly shows that shielded 600V RS485 cable routed in the raceway with the inverter output circuit to the MDP.
Anyway, it seems to be working. In my system the circuit is about 120 feet long one-way and the meter communication seems to be fine.
One thing I’m surprised at, though, is that the response of the Energy Storage Management System isn’t precise and instantaneous. For example, when I have it in “maximize self-consumption” mode, when the air conditioner turns on during daylight the system starts importing power from the grid for about a minute before the system fully powers the load from battery and PV and zeroes out the import from grid.

 

[jaggedben]

Jaggedben, are you referring to the breaker fastener in 690.10(E) and 408.36(D)? If so, I don’t think the requirement applies to grid interactive systems like StorEdge. 690.10(E) only applies to “multimode inverters in stand-alone systems” and 705.12(D)(5) repeats that the fastener of 408.36(D) doesn’t apply to utility-interactive inverters if listed and identified as utility interactive.

A multi-mode inverter in a stand alone system is exactly what it is, in backup mode. Also it is not an interactive output because it's the backup output. The point of 705.12 (D) is that interactive output breakers do not remain live if they accidentally pop off the panelboard busbars. The backup output of the StorEdge is precisely the opposite of that.

 

[ggunn]

A multi-mode inverter in a stand alone system is exactly what it is, in backup mode. Also it is not an interactive output because it's the backup output. The point of 705.12 (D) is that interactive output breakers do not remain live if they accidentally pop off the panelboard busbars. The backup output of the StorEdge is precisely the opposite of that.

I agree. The point of the exception to the breaker bolt down requirement is that that a power source that shuts down when it no longer sees a reference AC voltage does not need to be bolted down. Any power source that will continue to run under those conditions must have its interconnection breaker bolted down.

 

[SolarAlternativesDesign]

Then in the StorEdge the backfed breaker in the service panel would be exempt from 408.36(D). In the backed up loads panel 690.10(E) doesn't strictly apply because the system isn't a stand-alone system, but is the intent to interpret it as a stand-alone system during backup mode, and require the bolt down breaker in the backed up loads panel?

 

[jaggedben]

Yes I think that's the intent. The intent is that a plug on breaker that would remain energized from the terminals when no longer plugged onto the busbar should have a hold down.

 

[GoldDigger]

Normally a backed up loads panel would have to be fed through an ATS or MTS to isolate it from grid when grid is down.
When that ATS is inside the standalone or hybrid inverter system, then if that connects to a backfed breaker in the panel (no main connection present) then a hold down is doubly required since it will be backfed whether POCO or backup power is going to that panel.