Question on adding battery backup to microinverter grid-tie system

[Kawaja]

I have Enphase microinverters and 6.2 kW of Canadian Solar PV. I would like to add battery backup. If i put in two 5 kW Gyll batteries and a 12 kW Treeline (,or other) 48V Inverter/charger w/ ATS would that work ? Obviously w/o AC. Daily usage with AC is about 20kW. TIA

 

[svetz]

Not a good idea. If you want PV power when the grid is off you really need AC or DC coupling. Search the forums for "coupling" and you'll find folks asking the same things.

Normal inverters are voltage-sources, they only supply current when the voltage dips. Grid-Tied inverters are current-sources, they keep raising the voltage until they can push current; so they need a controller somewhere to turn them on/off or throttle their capability to be safe. There's a lot of engineering with the batteries and their SoC that needs to happen.

Enphase has the Ensemble system. I believe a number of companies (e.g., Outback, Tesla powerwall, Victron) all have AC coupling solutions compatible with Enphase.

 

[Kawaja]

Not a good idea. If you want PV power when the grid is off you really need AC or DC coupling. Search the forums for "coupling" and you'll find folks asking the same things.

Normal inverters are voltage-sources, they only supply current when the voltage dips. Grid-Tied inverters are current-sources, they keep raising the voltage until they can push current; so they need a controller somewhere to turn them on/off or throttle their capability to be safe. There's a lot of engineering with the batteries and their SoC that needs to happen.

Enphase has the Ensemble system. I believe a number of companies (e.g., Outback, Tesla powerwall, Victron) all have AC coupling solutions compatible with Enphase.

Svetz:
Thanks, for the direction on inverters, and I will look for those posts on coupling.

 

[Bubba_Nosferatu]

I have Enphase microinverters and 6.2 kW of Canadian Solar PV. I would like to add battery backup. If i put in two 5 kW Gyll batteries and a 12 kW Treeline (,or other) 48V Inverter/charger w/ ATS would that work ? Obviously w/o AC. Daily usage with AC is about 20kW. TIA

I'm considering the same thing, did you decide on an inverter or other find another solution?

 

[timselectric]

If you don't buy products that were designed for this. It can be difficult to make it work. And possibly dangerous to you or power company workers.
Which is not who not who you want to face in a lawsuit.

 

[BentleyJ]

Schneider Conext Pro 6848 is designed to work in an AC coupled fashion. I've been using one in such a set up for 3 years, no problems so far.

 

[newbostonconst]

I have a AC and DC coupled system with a Outback GS4048 and it works perfect if you know what you are doing. Sol-ark can do it also.

If the solar is on the input side of the Hybrid inverter it really isn't AC coupled. The micros would have to be on the output side of the hybrid inverter for the inverter to have the need to frequency shift and control the micros. So you likely can do it with any hybrid inverter but if they can't AC couple them the to output then you can't use the solar energy in a grid down situation.

 

[Kawaja]

Thanks for the additional solutions. I have not decided what to do, but leaning away from batteries,but still want ability to island and possibly add a smallish generator.

 

[Kawaja]

Just to close the loop- went with another 8kW of bifacial & iQ8As, a 30.7 EG4kW rack, Conext XW Pro 6.8 - and it is no longer DIY.
TTFN,

 

[zanydroid]

Just to close the loop- went with another 8kW of bifacial & iQ8As, a 30.7 EG4kW rack, Conext XW Pro 6.8 - and it is no longer DIY.
TTFN,

How stable is the AC coupling when grid is down?

 

[Kawaja]

Will report- final material delivered today, install next week.

 

[Kawaja]

Install of course delayed. During the mounting of equipment I actually asked a pertinent question, which stopped the wiring. Now they are swapping the Context for EG4 18KPV-12LV-240V HYBRID.

 

[Kawaja]

Working fine- only simulated grid outage; switches smoothly to battery power at night.