AC coupling for battery backup with grid tied system

[Anit767]

What I want - grid agnostic and battery agnostic system that can feed the grid and provide backup during a grid outage

What I have now - Solar Edge 3800H

victron inverters can work with Solaredge. Has anyone done this successfully? Are there better options out there?

AC-coupling and the Factor 1.0 rule [Victron Energy]

www.victronenergy.com

Need some help defining "Frequencies" in ESS for SolarEdge PV inverter - Victron Community

community.victronenergy.com

 

[mrzed001]

What I want - grid agnostic and battery agnostic system that can feed the grid and provide backup during a grid outage

What I have now - Solar Edge 3800H

victron inverters can work with Solaredge. Has anyone done this successfully? Are there better options out there?

AC-coupling and the Factor 1.0 rule [Victron Energy]

www.victronenergy.com

Need some help defining "Frequencies" in ESS for SolarEdge PV inverter - Victron Community

community.victronenergy.com

There are some other option like StorEdge ... but that is for EU only now (with cheap 48V battery).
Victron is one of the most reliable solution with cheap 48V battery.

Here is a bigger system where Victron inverter is AC coupled with two big Fronius:

 

[newbostonconst]

Are you meaning automatic/compatible? I am a little confused by your phase. It is likely me but I would love to increase my vocabulary.

 

[newbostonconst]

Here is a list of hybrid inverters that do backup and grid tie, many will AC couple. Sol-ark, Outback, are the ones some of us on here have used.

Hybrid Inverter | Hybrid Solar Inverter | altE

Hybrid inverters, mostly used in grid-tie solar systems, can provide backup power when the electric grid fails. Call 877-878-4060 to size your system today.

www.altestore.com

 

[Anit767]

I

Here is a list of hybrid inverters that do backup and grid tie, many will AC couple. Sol-ark, Outback, are the ones some of us on here have used.

Hybrid Inverter | Hybrid Solar Inverter | altE

Hybrid inverters, mostly used in grid-tie solar systems, can provide backup power when the electric grid fails. Call 877-878-4060 to size your system today.

www.altestore.com

Sol-Ark would be my first choice, but they cost around $6,000. I’ll look at the others. Thanks.

 

[Anit767]

Are you meaning automatic/compatible? I am a little confused by your phase. It is likely me but I would love to increase my vocabulary.

View attachment 62698

Battery agnostic - does not require the use of proprietary batteries, which can be ridiculously expensive.

 

[Hedges]

Does your Solar Edge implement "Frequency-Watts", reducing power output in response to increasing AC frequency above 60 Hz?
That is what's needed for nice operation in an AC coupled battery backup system (or some other scheme.)

Without Frequency-Watts, PV inverter will be knocked off line by frequency increase and battery will carry loads for 5 minutes until it comes back on line. Constant cycling of battery.

One more (the original) battery inverter for AC coupling is SMA Sunny Island. Here's the lowest priced eBay listing at the moment, and this is for a used one. These are 120V, so require a 120/240V transformer if just one is used.

SMA Sunny Island Off-Grid Inverter (SI6048-US-10) for sale online | eBay

Find many great new & used options and get the best deals for SMA Sunny Island Off-Grid Inverter (SI6048-US-10) at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Your lowest cost solution would be to rewire PV panels to a low-cost hybrid like MPP. Since you have Solar Edge, "Rapid Shutdown" is probably implemented by their optimizers so the problem with rewiring panels is that required feature would be lost.

 

[Anit767]

I

Sol-Ark would be my first choice, but they cost around $6,000. I’ll look at the others. Thanks.

I think I’m going to go with the Outback radian

 

[Hedges]

"Performs AC coupling with both legacy and UL1741SA inverters, using frequency shifting"

"Surge Power (5 sec): 12000VA (GS8048A) 6000VA (GS4048A)"

Motors draw a starting surge about 5x their nameplate rating, so expect to be able to start a 2400W rated motor with GS8048A or 1200W rated with GS4048A.

https://outbackpower.com/downloads/documents/inverter_chargers/radian_8048a_4048a/radianseries_8048a_4048a_specsheet.pdf

"All inverters are UL1741 SA certified, for CPUC Rule 21 grid compliance"

I don't know whether Solar Edge 3800H includes Frequency-Watts, which was (is?) an optional part of Rule 21 at one point. Make sure it does.

SolarEdge Home Wave Inverters

Maximize efficiency and safety with SolarEdge Home Wave Inverters - the trusted home energy managers, delivering enhanced performance.

www.solaredge.com

 

[Anit767]

"Performs AC coupling with both legacy and UL1741SA inverters, using frequency shifting"

"Surge Power (5 sec): 12000VA (GS8048A) 6000VA (GS4048A)"

Motors draw a starting surge about 5x their nameplate rating, so expect to be able to start a 2400W rated motor with GS8048A or 1200W rated with GS4048A.

https://outbackpower.com/downloads/documents/inverter_chargers/radian_8048a_4048a/radianseries_8048a_4048a_specsheet.pdf

"All inverters are UL1741 SA certified, for CPUC Rule 21 grid compliance"

I don't know whether Solar Edge 3800H includes Frequency-Watts, which was (is?) an optional part of Rule 21 at one point. Make sure it does.

SolarEdge Home Wave Inverters

Maximize efficiency and safety with SolarEdge Home Wave Inverters - the trusted home energy managers, delivering enhanced performance.

www.solaredge.com

Thank you.

 

[newbostonconst]

I have a GS4048 with microinverters by both Enphase and APsystems. The GS just has to have a firmware update to ac couple.

If you are smart with wiring you can do it without buying the lower box and use regular breaker boxes.

 

[Anit767]

I have a GS4048 with microinverters by both Enphase and APsystems. The GS just has to have a firmware update to ac couple.

If you are smart with wiring you can do it without buying the lower box and use regular breaker boxes.

I was wondering about that. Thanks.

Is there something else you have to buy to ac couple? what about firmware upgrades, does that require an additional purchase too?

 

[Hedges]

When both loads and all charging sources are AC coupled, there is a problem that battery drained at night can't recover even when sun comes up.

What I've done with my SMA system is connect AC coupled PV (Sunny Boy) directly to output of battery inverter (Sunny Island), and use a "load-shed" relay to disconnect loads (house) based on a control signal for low battery SoC. This sheds all load at 70% DoD, leaving 10% to keep AC running waiting for Sunny Boys to wake up. If battery reaches 80% DoD, then Sunny Island would shut off.

Adding some DC coupled PV is another solution, probably already built in to the Radian.

It would also be useful to enable/disable large loads (e.g. A/C) based on SoC, so they only run when surplus PV or battery capacity is available. Save your limited stored power for more important loads.

 

[newbostonconst]

I was wondering about that. Thanks.

Is there something else you have to buy to ac couple? what about firmware upgrades, does that require an additional purchase too?

Firmware is free.

Yes as Hedges said you can add a DC charge controller to charge the batteries if needed. I haven't run into that because I have a 25kWh battery bank and conserve when on battery.